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| ? 2011 microchip technology inc. ds25095a-page 1 mcp9808 features ?accuracy: - 0.25 (typical) from -40c to +125c - 0.5c (maximum) from -20c to 100c - 1c (maximum) from -40c to +125c ? user-selectable measurement resolution: - +0.5c, +0.25c, +0.125c, +0.0625c ? user-programmable temperature limits: - temperature window limit - critical temperature limit ? user-programmable temperature alert output ? operating voltage range: 2.7v to 5.5v ? operating current: 200 a (typical) ? shutdown current: 0.1 a (typical) ? 2-wire interface: i 2 c?/smbus compatible ? available packages: 2x3 dfn-8, msop-8 typical applications ? general purpose ? industrial applications ? industrial freezers and refrigerators ? food processing ? personal computers and servers ? pc peripherals ? consumer electronics ? handheld/portable devices temperature accuracy description microchip technology inc.?s mcp9808 digital temperature sensor converts temperatures between -20c and +100c to a digital word with 0.25c/0.5c (typical/maximum) accuracy. the mcp9808 comes with user-programmable registers that provide flexibility for temperature sensing applications. the registers allow user-selectable settings such as shutdown or low-power modes and the specification of temperature alert window limits and critical output limits. when the temperature changes beyond the specified boundary limits, the mcp9808 outputs an alert signal. the user has the option of setting the alert output signal polarity as an active-low or active- high comparator output for t hermostat operation, or as a temperature alert interrupt output for microprocessor- based systems. the alert output can also be configured as a critical temperature output only. this sensor has an industry standard 400 khz, 2-wire, smbus/i 2 c compatible serial interface, allowing up to eight or sixteen sensors to be controlled with a single serial bus (see ta b l e 3 - 2 for available address codes). these features make the mcp9808 ideal for sophisticated, multi-zone, temperature-monitoring applications. package types 0% 10% 20% 30% 40% -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 occurrences temperature accuracy (c) t a = -20 c, 25 c, 85 c, 100 c v dd = 3.3v 854 units 8-pin 2x3 dfn* 1 2 3 4 8-pin msop 8 7 6 5 * includes exposed thermal pad (ep); see table 3-1 . a1 a0 a2 scl alert 1 2 3 4 8 7 6 5 gnd sda v dd ep 9 scl alert gnd sda a1 a0 a2 v dd 0.5c maximum accuracy digital temperature sensor
mcp9808 ds25095a-page 2 ? 2011 microchip technology inc. functional block diagram clear alert +0.5c +0.25c +0.125c +0.0625c temperature t lower limit configuration ? adc band gap temperature sensor alert status output control critical alert only alert polarity alert comp./int. t critical limit register pointer critical trip lock alarm window lock shutdown hysteresis manufacturer id resolution device id/rev smbus/standard i 2 c? interface a0 a1 a2 alert sda scl v dd gnd t upper limit ? 2011 microchip technology inc. ds25095a-page 3 mcp9808 1.0 electrical characteristics absolute maximum ratings ? v dd .................................................................................. 6.0v voltage at all input/output pins .............. gnd ? 0.3v to 6.0v storage temperature ....................................-65c to +150c ambient temperature with power applied ....-40c to +125c junction temperature (t j ) .......................................... +150c esd protection on all pins (hbm:mm) ................ (4 kv:400v) latch-up current at each pin (+25c) ..................... 200 ma ?notice: stresses above those listed under ?maximum ratings? may cause permanent damage to the device. this is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. exposure to maximum rating conditions for extended periods may affect device reliability. temperature sensor dc characteristics electrical specifications: unless otherwise indicated, v dd = 2.7v to 5.5v, gnd = ground and t a = -40c to +125c. parameters sym min typ max unit conditions temperature sensor accuracy -20c < t a +100c t acy t acy -0.5 0.25 +0.5 c v dd = 3.3v -40c < t a +125c -1.0 0.25 +1.0 c v dd = 3.3v temperature conversion time 0.5c/bit t conv ? 30 ? ms 33s/sec (typical) 0.25c/bit ? 65 ? ms 15s/sec (typical) 0.125c/bit ? 130 ? ms 7s/sec (typical) 0.0625c/bit ? 250 ? ms 4s/sec (typical) power supply operating voltage range v dd 2.7 ? 5.5 v operating current i dd ?200 400 a shutdown current i shdn ?0.1 2 a power-on reset (por) v por ? 2.2 ? v threshold for falling v dd power supply rejection c/ v dd ?-0.1 ? c/vv dd = 2.7v to 5.5v, t a = +25c alert output (open-drain output, external pull-up resistor required), see section 5.2.3 ?alert output configuration? high-level current (leakage) i oh ?? 1 av oh = v dd (active-low, pull-up resistor) low-level voltage v ol ?? 0.4 vi ol = 3 ma (active-low, pull-up resistor) thermal response, from +25c (air) to +125c (oil bath) 8l-dfn t res ? 0.7 ? s time to 63% (+89c) 8l-msop ? 1.4 ? s mcp9808 ds25095a-page 4 ? 2011 microchip technology inc. graphical symbol description digital input/output pin characteristics electrical specifications: unless otherwise indicated, v dd = 2.7v to 5.5v, gnd = ground and t a = -40c to +125c. parameters sym min typ max units conditions serial input/output (scl, sda, a0, a1, a2) input high-level voltage v ih 0.7 v dd ?v dd v low-level voltage v il gnd ? 0.3 v dd v input current i in ??5a output (sda) low-level voltage v ol ??0.4vi ol = 3 ma high-level current (leakage) i oh ??1av oh = 5.5v low-level current i ol 6??mav ol = 0.6v sda and scl inputs hysteresis v hyst ?0.05 v dd ?v spike suppression t sp ??50ns capacitance c in ?5?pf v dd v ih v il i in voltage current time v dd i oh voltage current time input output v ol i ol temperature characteristics electrical specifications: unless otherwise indicated, v dd = 2.7v to 5.5v and gnd = ground. parameters sym min typ max units conditions temperature ranges specified temperature range t a -40 ? +125 c ( note 1 ) operating temperature range t a -40 ? +125 c storage temperature range t a -65 ? +150 c thermal package resistances thermal resistance, 8l-dfn ja ?68?c/w thermal resistance, 8l-msop ja ?211?c/w note 1: operation in this range must not cause t j to exceed maximum junction temperature (+150c). ? 2011 microchip technology inc. ds25095a-page 5 mcp9808 timing diagram sensor serial interface timing specifications electrical specifications: unless otherwise indicated, v dd = 2.7v to 5.5v, t a = -40c to +125c, gnd = ground and c l = 80 pf. ( note 1 ) parameters sym min max units conditions 2-wire smbus/standard mode i 2 c? compatible interface ( note 1 ) serial port clock frequency f sc 0400khz ( note 2 , 4 ) low clock t low 1300 ? ns ( note 2 ) high clock t high 600 ? ns ( note 2 ) rise time t r 20 300 ns fall time t f 20 300 ns data in setup time t su-di 100 ? ns ( note 3 ) data in hold time t hd-di 0?ns ( note 5 ) data out hold time t hd-do 200 900 ns ( note 4 ) start condition setup time t su-start 600 ? ns start condition hold time t hd-start 600 ? ns stop condition setup time t su-stop 600 ? ns bus free t b-free 1300 ? ns time-out t out 25 35 ms bus capacitive load c b ?400pf note 1: all values referred to v il max and v ih min levels. 2: if t low > t out or t high > t out , the temperature sensor i 2 c interface will time-out. a repeat start command is required for communication. 3: this device can be used in a standard mode i 2 c bus system, but the requirement, t su-di 100 ns, must be met. this device does not stretch the scl low time. 4: as a transmitter, the device provides internal minimum delay time, t hd-do min , to bridge the undefined region (min. 200 ns) of the falling edge of scl, t f max , to avoid unintended generation of start or stop conditions. 5: as a receiver, sda should not be sampled at the falling edge of scl. sda can transition t hd-di 0 ns after scl toggles low. t su-start t hd-start t su-di t su-stop t b-free scl sda t hd-di/ t hd-do t high t low t out t r , t f start condition data transmission stop condition mcp9808 ds25095a-page 6 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 7 mcp9808 2.0 typical performance curves note: unless otherwise indicated, v dd = 2.7v to 5.5v, gnd = ground, sda/scl pulled-up to v dd and t a = -40c to +125c. figure 2-1: temperature accuracy. figure 2-2: temperature accuracy histogram, t a = -20c. figure 2-3: temperature accuracy histogram, t a = +25c. figure 2-4: temperature accuracy histogram. figure 2-5: temperature accuracy histogram, t a = +85c. figure 2-6: temperature accuracy histogram, t a = +100c. note: the graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. the performance characteristics listed herein are not tested or guaranteed. in some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. -1.0 -0.5 0.0 0.5 1.0 -40 -20 0 20 40 60 80 100 120 temperature accuracy (c) t a (c) v dd = 3.3v 854 units at -20 c, 25 c, 85 c, 100 c 240 units at -40 c, 125 c +std. dev. average -std. dev. +3 * std. dev. -3 * std. dev. 0% 10% 20% 30% 40% -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 occurrences temperature accuracy (c) t a = -20 c v dd = 3.3v 827 units 0% 10% 20% 30% 40% -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 occurrences temperature accuracy (c) t a = 25 c v dd = 3.3v 875 units 0% 10% 20% 30% 40% -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 occurrences temperature accuracy (c) t a = -20 c, 25 c, 85 c, 100 c v dd = 3.3v 854 units 0% 10% 20% 30% 40% -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 occurrences temperature accuracy (c) t a = 85 c v dd = 3.3v 859 units 0% 10% 20% 30% 40% -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 occurrences temperature accuracy (c) t a = 100 c v dd = 3.3v 856 units mcp9808 ds25095a-page 8 ? 2011 microchip technology inc. note: unless otherwise indicated, v dd = 2.7v to 5.5v, gnd = ground, sda/scl pulled-up to v dd and t a = -40c to +125c. figure 2-7: temperature accuracy histogram, t a = -40c. figure 2-8: supply current vs. temperature. figure 2-9: power-on reset threshold voltage vs. temperature. figure 2-10: temperature accuracy histogram, t a = +125c. figure 2-11: temperature accuracy vs supply voltage. figure 2-12: temperature conversion time vs. temperature. 0% 10% 20% 30% 40% -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 occurrences temperature accuracy (c) t a = -40 c v dd = 3.3v 240 units 100 150 200 250 300 350 400 -40-20 0 20406080100120 temperature (c) i dd (a) 1 1.5 2 2.5 3 -40 -20 0 20 40 60 80 100 120 temperature (c) v por (v) 0% 10% 20% 30% 40% -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 occurrences temperature accuracy (c) t a = 125 c v dd = 3.3v 240 units -1.00 -0.50 0.00 0.50 1.00 -40 -20 0 20 40 60 80 100 120 temperature (c) temperature accuracy (c) ? c/ ? v dd = 0.1c/v v dd = 2.7v v dd = 3.3v v dd = 5.5v 10 100 1000 -40-20 0 20406080100120 temperature (c) t conv (ms) 0.0625c 0.125c 0.25c 0.5c ? 2011 microchip technology inc. ds25095a-page 9 mcp9808 note: unless otherwise indicated, v dd = 2.7v to 5.5v, gnd = ground, sda/scl pulled-up to v dd and t a = -40c to +125c. figure 2-13: sda and alert output v ol vs. temperature. figure 2-14: sda i ol vs. temperature. figure 2-15: package thermal response. figure 2-16: smbus time-out vs. temperature. figure 2-17: shutdown current vs temperature. figure 2-18: power supply rejection vs. frequency. 0 0.1 0.2 0.3 0.4 -40 -20 0 20 40 60 80 100 120 temperature (c) sda & alert output v ol (v) alert v ol sda v ol i ol = 3 ma 6 12 18 24 30 36 42 48 -40 -20 0 20 40 60 80 100 120 temperature (c) sda i ol (ma) v ol = 0.6v 0% 20% 40% 60% 80% 100% 120% -2 0 2 4 6 8 10 12 14 16 time (s) thermal response (%) room to +125c (oil bath) msop-8 dfn-8 20 25 30 35 -40 -20 0 20 40 60 80 100 120 temperature (c) smbus/i 2 c bus t out (ms) 0.00 0.50 1.00 1.50 2.00 -40 -20 0 20 40 60 80 100 120 temperature (c ) i shdn (a) -1.0 -0.5 0.0 0.5 1.0 100 1,000 10,000 100,000 1,000,000 frequency (hz) normalized temp. error (c) ? c/ ? v dd , v dd = 3.3v + 150 mv pp (ac) t a = 25c 1k 10k 100k 1m 100k 1m 10k 100k 1m 1k 10k 100k 1m 100 1k 10k 100k 1m t a = +25c no decoupling capacitor mcp9808 ds25095a-page 10 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 11 mcp9808 3.0 pin description the descriptions of the pins are listed in tab l e 3 - 1 . 3.1 serial data line (sda) sda is a bidirectional input/output pin, used to serially transmit data to/from the host controller. this pin requires a pull-up resistor. (see section 4.0 ?serial communication? .) 3.2 serial clock line (scl) the scl is a clock input pin. all communication and timing is relative to the signal on this pin. the clock is generated by the host or master controller on the bus. (see section 4.0 ?serial communication? .) 3.3 temperature alert, open-drain output (alert) the mcp9808 temperature alert output pin is an open-drain output. the device outputs a signal when the ambient temperature goes beyond the user-programmed temperature limit. (see section 5.2.3 ?alert output configuration? ). 3.4 ground pin (gnd) the gnd pin is the system ground pin. 3.5 address pins (a0, a1, a2) these pins are device address input pins. the address pins correspond to the least significant bits (lsbs) of the address bits and the most significant bits (msbs): a6, a5, a4, a3. this is illustrated in table 3-2 . 3.6 power pin (v dd ) v dd is the power pin. the operating voltage range, as specified in the dc electrical specification table, is applied on this pin. 3.7 exposed thermal pad (ep) there is an internal electrical connection between the exposed thermal pad (ep) and the gnd pin. the ep may be connected to the system ground on the printed circuit board (pcb). table 3-1: pin function table dfn msop symbol pin function 1 1 sda serial data line 2 2 scl serial clock line 3 3 alert temperature alert output 44 gndground 5 5 a2 slave address 6 6 a1 slave address 7 7 a0 slave address 88 v dd power pin 9 ? ep exposed thermal pad (ep); must be connected to gnd table 3-2: mcp9808 address byte device address code slave address a6 a5 a4 a3 a2 a1 a0 mcp9808 0011x ( 1 ) xx mcp9808 ( 2 ) 1001 xxx note 1: user-selectable address is shown by ? x ?. a2, a1 and a0 must match the corresponding device pin configuration. 2: contact factory for this address code. mcp9808 ds25095a-page 12 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 13 mcp9808 4.0 serial communication 4.1 2-wire standard mode i 2 c? protocol compatible interface the mcp9808 serial clock (scl) input and the bidirectional serial data (sda) line form a 2-wire bidirectional, standard mode, i 2 c compatible communication port (refer to the digital input/output pin characteristics and sensor serial interface timing specifications tables). the following bus protocol has been defined: 4.1.1 data transfer data transfers are initiated by a start condition (start), followed by a 7-bit device address and a read/write bit. an acknowledge (ack) from the slave confirms the reception of each byte. each access must be terminated by a stop condition (stop). repeated communication is initiated after t b-free . this device does not support sequential register read/write. each register needs to be addressed using the register pointer. this device supports the receive protocol. the register can be specified using the pointer for the initial read. each repeated read or receive begins with a start condition and address byte. the mcp9808 retains the previously selected register. therefore, it outputs data from the previously specified register (repeated pointer specification is not necessary). 4.1.2 master/slave the bus is controlled by a master device (typically a microcontroller) that controls the bus access and generates the start and stop conditions. the mcp9808 is a slave device and does not control other devices in the bus. both master and slave devices can operate as either transmitter or receiver. however, the master device determines which mode is activated. 4.1.3 start/stop condition a high-to-low transition of the sda line (while scl is high) is the start condition. all data transfers must be preceded by a start condition from the master. a low-to-high transition of the sda line (while scl is high) signifies a stop condition. if a start or stop condition is introduced during data transmission, the mcp9808 releases the bus. all data transfers are ended by a stop condition from the master. table 4-1: mcp9808 serial bus protocol descriptions term description master the device that controls the serial bus, typically a microcontroller. slave the device addressed by the master, such as the mcp9808. transmitter device sending data to the bus. receiver device receiving data from the bus. start a unique signal from the master to initiate serial interface with a slave. stop a unique signal from the master to terminate serial interface from a slave. read/write a read or write to the mcp9808 registers. ack a receiver acknowledges (ack) the reception of each byte by polling the bus. nak a receiver not-acknowledges (nak) or releases the bus to show end-of-data (eod). busy communication is not possible because the bus is in use. not busy the bus is in the idle state; both sda and scl remain high. data valid sda must remain stable before scl becomes high in order for a data bit to be considered valid. during normal data transfers, sda only changes state while scl is low. mcp9808 ds25095a-page 14 ? 2011 microchip technology inc. 4.1.4 address byte following the start condition, the host must transmit an 8-bit address byte to the mcp9808. the address for the mcp9808 temperature sensor is ? 0011,a2,a1,a0 ? in binary, where the a2, a1 and a0 bits are set externally by connecting the corresponding pins to v dd ? 1 ? or gnd ? 0 ?. the 7-bit address, transmitted in the serial bit stream, must match the selected address for the mcp9808 to respond with an ack. bit 8 in the address byte is a read/write bit. setting this bit to ? 1 ? commands a read operation, while ? 0 ? commands a write operation (see figure 4-1 ). figure 4-1: device addressing. 4.1.5 data valid after the start condition, each bit of data in the transmission needs to be settled for a time specified by t su-data before scl toggles from low-to-high (see the sensor serial interface timing specifications section). 4.1.6 acknowledge (ack/nak) each receiving device, when addressed, must generate an ack bit after the reception of each byte. the master device must generate an extra clock pulse for ack to be recognized. the acknowledging device pulls down the sda line for t su-data before the low-to-high transition of scl from the master. sda also needs to remain pulled down for t h-data after a high-to-low transition of scl. during read, the master must signal an end-of-data (eod) to the slave, by not generating an ack bit (nak), once the last bit has been clocked out of the slave. in this case, the slave will leave the data line released to enable the master to generate the stop condition. 4.1.7 time-out if the scl stays low or high for the time specified by t out , the mcp9808 temperature sensor resets the serial interface. this dictates the minimum clock speed as outlined in the specification. 123456789 scl sda 011a2a1a0 start address byte slave address r/w mcp9808 response code address a c k 0 see table 3-2 . ? 2011 microchip technology inc. ds25095a-page 15 mcp9808 5.0 functional description the mcp9808 temperature sensors consist of a band- gap-type temperature sensor, a delta-sigma analog-to- digital converter ( ? adc), user-programmable registers and a 2-wire smbus/i 2 c protocol compatible serial interface. figure 5-1 shows a block diagram of the register structure. figure 5-1: functional block diagram. clear alert +0.5c +0.25c +0.125c +0.0625c temperature t lower limit configuration ? adc band gap temperature sensor alert status output control critical alert only alert polarity alert comp/int t critical limit register pointer critical trip lock alarm win. lock shutdown hysteresis manufacturer id resolution device id/rev smbus/standard i 2 c? interface a0 a1 a2 alert sda scl v dd gnd t upper limit mcp9808 ds25095a-page 16 ? 2011 microchip technology inc. 5.1 registers the mcp9808 has several registers that are user-accessible. these registers include the tempera- ture register, configuration register, temperature alert upper boundary and lower boundary limit registers, critical temperature limit register, manufacturer identification register and device identification register. the temperature register is read-only, used to access the ambient temperature data. this register is double- buffered and it is updated every t conv . the temperature alert upper boundary and lower boundary limit registers are read/write registers. if the ambient temperature drifts beyond the user-specified limits, the mcp9808 outputs a signal using the alert pin (refer to section 5.2.3 ?alert output configuration? ). in addition, the critical temperature limit register is used to provide an additional critical temperature limit. the configuration register provides access to configure the mcp9808 device?s various features. these registers are described in further detail in the following sections. the registers are accessed by sending a register pointer to the mcp9808, using the serial interface. this is an 8-bit write-only pointer. however, the four least significant bits are used as pointers and all unused bits (register pointer<7:4>) need to be cleared or set to ? 0 ?. register 5-1 describes the pointer or the address of each register. register 5-1: register pointer (write-only) w-0 w-0 w-0 w-0 w-0 w-0 w-0 w-0 ? ? ? ? pointer bits bit 7 bit 0 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? -n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown bit 7-4 w: writable bits write ? 0 ?. bits 7-4 must always be cleared or written to ? 0 ?. this device has additional registers that are reserved for test and calibration. if these registers are accessed, the device may not perform according to the specification. bit 3-0 pointer bits 0000 = rfu, reserved for future use (read-only register) 0001 = configuration register (config) 0010 = alert temperature upper boundary trip register (t upper ) 0011 = alert temperature lower boundary trip register (t lower ) 0100 = critical temperature trip register (t crit ) 0101 = temperature register (t a ) 0110 = manufacturer id register 0111 = device id/revision register 1000 = resolution register 1xxx = reserved ( 1 ) note 1: some registers contain calibration codes and should not be accessed. ? 2011 microchip technology inc. ds25095a-page 17 mcp9808 table 5-1: bit assignment summary for all registers (see section 5.3 ?summary of power-on default? for power-on defaults) register pointer (hex) msb/ lsb bit assignment 76 5 43210 0x00 msb 0 0 0 0 0 0 0 0 lsb 0 0 0 1 1 1 1 1 0x01 msb 00 0 00 hysteresis shdn lsb crt loc win loc int clr alt stat alt cnt alt sel alt pol alt mod 0x02 msb 0 0 0 sign 2 7 c 2 6 c 2 5 c 2 4 c lsb 2 3 c 2 2 c 2 1 c 2 0 c 2 -1 c 2 -2 c 0 0 0x03 msb 00 0 sign 2 7 c 2 6 c 2 5 c 2 4 c lsb 2 3 c 2 2 c 2 1 c 2 0 c 2 -1 c 2 -2 c 00 0x04 msb 0 0 0 sign 2 7 c 2 6 c 2 5 c 2 4 c lsb 2 3 c 2 2 c 2 1 c 2 0 c 2 -1 c 2 -2 c 0 0 0x05 msb t a t crit t a > t upper t a < t lower sign 2 7 c 2 6 c 2 5 c 2 4 c lsb 2 3 c 2 2 c 2 1 c 2 0 c 2 -1 c 2 -2 c 2 - 3 c 2 - 4 c 0x06 msb 0 0 0 0 0 0 0 0 lsb 0 1 0 1 0 1 0 0 0x07 msb 00 0 00100 lsb 00 0 00000 0x08 lsb 0 0 0 0 0 0 1 1 mcp9808 ds25095a-page 18 ? 2011 microchip technology inc. 5.1.1 sensor configuration register (config) the mcp9808 has a 16-bit configuration register (config) that allows the user to set various functions for a robust temperature monitoring system. bits 10 through 0 are used to select the temperature alert output hysteresis, device shutdown or low-power mode, temperature boundary and critical temperature lock, and temperature alert output enable/disable. in addition, alert output condition (output set for t upper and t lower temperature boundary or t crit only), alert output status and alert output polarity and mode (comparator output or interrupt output mode) are user-configurable. the temperature hysteresis bits 10 and 9 can be used to prevent output chatter when the ambient temperature gradually changes beyond the user-specified temperature boundary (see section 5.2.2 ?temperature hysteresis (t hyst )? . the continuous conversion or shutdown mode is selected using bit 8. in shutdown mode, the band gap temperature sensor circuit stops converting temperature and the ambient temperature register (t a ) holds the previous temperature data (see section 5.2.1 ?shutdown mode? ). bits 7 and 6 are used to lock the user-specified boundaries t upper , t lower and t crit to prevent an accidental rewrite. the lock bits are cleared by resetting the power. bits 5 through 0 are used to configure the temperature alert output pin. all functions are described in register 5-2 (see section 5.2.3 ?alert output configuration? ). register 5-2: config: configuration register ( address ?0000 0001?b ) u-0 u-0 u-0 u-0 u-0 r/w-0 r/w-0 r/w-0 ? ? ? ? ?t hyst shdn bit 15 bit 8 r/w-0 r/w-0 r/w-0 r-0 r/w-0 r/w-0 r/w-0 r/w-0 crit. lock win. lock int. clear alert stat. alert cnt. alert sel. alert pol. alert mod. bit 7 bit 0 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? -n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown bit 15-11 unimplemented: read as ? 0 ? bit 10-9 t hyst : t upper and t lower limit hysteresis bits 00 = 0c (power-up default) 01 =+1.5c 10 =+3.0c 11 =+6.0c (refer to section 5.2.3 ?alert output configuration? .) this bit can not be altered when either of the lock bits are set (bit 6 and bit 7). this bit can be programmed in shutdown mode. bit 8 shdn: shutdown mode bit 0 = continuous conversion (power-up default) 1 = shutdown (low-power mode) in shutdown, all power-consuming activities are disabled, though all registers can be written to or read. this bit cannot be set to ? 1 ? when either of the lock bits is set (bit 6 and bit 7). however, it can be cleared to ? 0 ? for continuous conversion while locked (refer to section 5.2.1 ?shutdown mode? ). ? 2011 microchip technology inc. ds25095a-page 19 mcp9808 bit 7 crit. lock: t crit lock bit 0 = unlocked. t crit register can be written (power-up default) 1 = locked. t crit register can not be written when enabled, this bit remains set to ? 1 ? or locked until cleared by an internal reset ( section 5.3 ?summary of power-on default? ). this bit can be programmed in shutdown mode. bit 6 win. lock: t upper and t lower window lock bit 0 = unlocked; t upper and t lower registers can be written (power-up default) 1 = locked; t upper and t lower registers can not be written when enabled, this bit remains set to ? 1 ? or locked until cleared by a power-on reset ( section 5.3 ?summary of power-on default? ). this bit can be programmed in shutdown mode. bit 5 int. clear: interrupt clear bit 0 = no effect (power-up default) 1 = clear interrupt output; when read, this bit returns to ? 0 ? this bit can not be set to ? 1 ? in shutdown mode, but it can be cleared after the device enters shutdown mode. bit 4 alert stat.: alert output status bit 0 = alert output is not asserted by the device (power-up default) 1 = alert output is asserted as a comparator/interrupt or critical temperature output this bit can not be set to ? 1 ? or cleared to ? 0 ? in shutdown mode. however, if the alert output is config- ured as interrupt mode, and if the host controller clears to ? 0 ?, the interrupt, using bit 5 while the device is in shutdown mode, then this bit will also be cleared ? 0 ?. bit 3 alert cnt.: alert output control bit 0 = disabled (power-up default) 1 = enabled this bit can not be altered when either of the lock bits are set (bit 6 and bit 7). this bit can be programmed in shutdown mode, but the alert output will not assert or deassert. bit 2 alert sel.: alert output select bit 0 = alert output for t upper , t lower and t crit (power-up default) 1 =t a > t crit only (t upper and t lower temperature boundaries are disabled) when the alarm window lock bit is set, this bit cannot be altered until unlocked (bit 6). this bit can be programmed in shutdown mode, but the alert output will not assert or deassert. bit 1 alert pol.: alert output polarity bit 0 = active-low (power-up default; pull-up resistor required) 1 = active-high this bit cannot be altered when either of the lock bits are set (bit 6 and bit 7). this bit can be programmed in shutdown mode, but the alert output will not assert or deassert. bit 0 alert mod.: alert output mode bit 0 = comparator output (power-up default) 1 = interrupt output this bit cannot be altered when either of the lock bits are set (bit 6 and bit 7). this bit can be programmed in shutdown mode, but the alert output will not assert or deassert. register 5-2: config: configuration register ( address ?0000 0001?b ) mcp9808 ds25095a-page 20 ? 2011 microchip technology inc. figure 5-2: timing diagram for writing to the configuration register (see section 4.0 ?serial communication? ). writing to the config register to enable the event output pin <0000 0000 0000 1000>b: sda a c k 0011 a 0000 a c k s 2 a 1 a 0 12345678 12345678 scl 0 address byte w mcp9808 mcp9808 msb data a c k a c k p 12345678 12345678 lsb data configuration pointer mcp9808 mcp9808 001 00000 000 00001 000 note: this is an example routine (see appendix a: ?source code? ). i2c_start(); // send start command i2c_write(addressbyte & 0xfe); //write command (see section 4.1.4 ?address byte? ) //also, make sure bit 0 is cleared ?0? i2c_write(0x01); // write config register i2c_write(0x00); // write data i2c_write(0x08); // write data i2c_stop(); // send stop command ? 2011 microchip technology inc. ds25095a-page 21 mcp9808 figure 5-3: timing diagram for reading from the configuration register (see section 4.0 ?serial communication? ). sda a c k 0011 a configuration pointer 0000 a c k s 2 a 1 a 0 12345678 12345678 scl 0 address byte a c k 0011 a msb data a c k n a k s p 2 a 1 a 0 12345678 12345678 12345678 address byte lsb data r mcp9808 mcp9808 mcp9808 master master w sda scl 001 00000 000 00001 000 reading the config register: note: it is not necessary to select the register pointer if it was set from the previous read/write. note: this is an example routine (see appendix a: ?source code? ). i2c_start(); // send start command i2c_write(addressbyte & 0xfe); //write command (see section 4.1.4 ?address byte? ) //also, make sure bit 0 is cleared ?0? i2c_write(0x01); // write config register i2c_start(); // send repeat start command i2c_write(addressbyte | 0x01); //read command //also, make sure bit 0 is set ?1? upperbyte = i2c_read(ack); // read 8 bits //and send ack bit lowerbyte = i2c_read(nak); // read 8 bits //and send nak bit i2c_stop(); // send stop command mcp9808 ds25095a-page 22 ? 2011 microchip technology inc. 5.1.2 upper/lower/critical temperature limit registers (t upper /t lower /t crit ) the mcp9808 has a 16-bit read/write alert output temperature upper boundary register (t upper ), a 16-bit lower boundary register (t lower ) and a 16-bit critical boundary register (t crit ) that contain 11-bit data in two?s complement format (0.25c). this data represents the maximum and minimum temperature boundary or temperature window that can be used to monitor ambient temperature. if this feature is enabled ( section 5.1.1 ?sensor configuration register (config)? ) and the ambient temperature exceeds the specified boundary or window, the mcp9808 asserts an alert output. (refer to section 5.2.3 ?alert output configuration? ). register 5-3: t upper /t lower /t crit upper/lower/critical temperature limit register ( address ?0000 0010?b/?0000 0011?b/?0000 0100?b) ( 1 ) u-0 u-0 u-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 ? ? ?sign2 7 c 2 6 c 2 5 c 2 4 c bit 15 bit 8 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 r/w-0 u-0 u-0 2 3 c 2 2 c 2 1 c 2 0 c 2 -1 c 2 -2 c ? ? bit 7 bit 0 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? -n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown bit 15-13 unimplemented: read as ? 0 ? bit 12 sign: sign bit 0 =t a 0c 1 =t a < 0c bit 11-2 t upper /t lower /t crit : temperature boundary bits temperature boundary trip data in two?s complement format. bit 1-0 unimplemented: read as ? 0 ? note 1: this table shows two 16-bit registers for t upper , t lower and t crit , located at ? 0000 0010b ?, ? 0000 0011b ? and ? 0000 0100b ?, respectively. ? 2011 microchip technology inc. ds25095a-page 23 mcp9808 figure 5-4: timing diagram for writing and reading from the t upper register (see section 4.0 ?serial communication? ). sda a c k 0011 a t upper pointer 0000 a c k s 2 a 1 a 0 12345678 12345678 scl 0 address byte a c k 0011 a msb data a c k n a k s p 2 a 1 a 0 12345678 12345678 12345678 address byte lsb data r mcp9808 mcp9808 mcp9808 master master w sda scl 010 00000 101 10100 000 reading from the t upper register: writing +90c to the t upper register <0000 0101 1010 0000>b : sda a c k 0011 a 0000 a c k s 2 a 1 a 0 12345678 12345678 scl 0 address byte w mcp9808 mcp9808 msb data a c k a c k p 12345678 12345678 lsb data t upper pointer mcp9808 mcp9808 010 00000 101 10100 000 note: it is not necessary to select the register pointer if it was set from the previous read/write. mcp9808 ds25095a-page 24 ? 2011 microchip technology inc. 5.1.3 ambient temperature register (t a ) the mcp9808 uses a band gap temperature sensor circuit to output analog voltage proportional to absolute temperature. an internal ? adc is used to convert the analog voltage to a digital word. the digital word is loaded to a 16-bit read-only ambient temperature register (t a ) that contains 13-bit temperature data in two?s complement format. the t a register bits (t a <12:0>) are double-buffered. therefore, the user can access the register, while in the background, the mcp9808 performs an analog-to- digital conversion. the temperature data from the ? adc is loaded in parallel to the t a register at t conv refresh rate. in addition, the t a register uses three bits (t a <15:13>) to reflect the alert pin state. this allows the user to identify the cause of the alert output trigger (see section 5.2.3 ?alert output configuration? ); bit 15 is set to ? 1 ? if t a is greater than or equal to t crit , bit 14 is set to ? 1 ? if t a is greater than t upper and bit 13 is set to ? 1 ? if t a is less than t lower . the t a register bit assignment and boundary conditions are described in register 5-4 . register 5-4: t a : ambient temperature register ( address ?0000 0101?b ) ( 1 ) r-0 r-0 r-0 r-0 r-0 r-0 r-0 r-0 t a vs. t crit ( 1 ) t a vs. t upper ( 1 ) t a vs. t lower ( 1 ) sign 2 7 c 2 6 c 2 5 c 2 4 c bit 15 bit 8 r-0 r-0 r-0 r-0 r-0 r-0 r-0 r-0 2 3 c 2 2 c 2 1 c 2 0 c 2 -1 c 2 -2 c ( 2 ) 2 -3 c ( 2 ) 2 -4 c ( 2 ) bit 7 bit 0 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? -n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown bit 15 t a vs. t crit bit ( 1 ) 0 =t a < t crit 1 =t a t crit bit 14 t a vs. t upper bit ( 1 ) 0 =t a t upper 1 =t a > t upper bit 13 t a vs. t lower bit ( 1 ) 0 =t a t lower 1 =t a < t lower bit 12 sign bit 0 =t a 0c 1 =t a < 0c bit 11-0 t a : ambient temperature bits ( 2 ) 12-bit ambient temperature data in two?s complement format. note 1: bits 15, 14 and 13 are not affected by the status of the alert output configuration (config<5:0> bits, register 5-2 ). 2: bits 2, 1 and 0 may remain clear at ? 0 ? depending on the status of the resolution register ( register 5-7 ). the power-up default is 0.25c/bit; bits 1 and 0 remain clear ? 0 ?. ? 2011 microchip technology inc. ds25095a-page 25 mcp9808 5.1.3.1 t a bits to temperature conversion to convert the t a bits to decimal temperature, the upper three boundary bits (t a <15:13>) must be masked out. then, determine the sign bit (bit 12) to check positive or negative temperature, shift the bits accordingly, and combine the upper and lower bytes of the 16-bit register. the upper byte contains data for temperatures greater than +32c while the lower byte contains data for temperature less than +32c, includ- ing fractional data. when combining the upper and lower bytes, the upper byte must be right-shifted by 4 bits (or multiply by 2 4 ) and the lower byte must be left- shifted by 4 bits (or multiply by 2 -4 ). adding the results of the shifted values provides the temperature data in decimal format (see equation 5-1 ). the temperature bits are in two?s compliment format, therefore, positive temperature data and negative tem- perature data are computed differently. equation 5-1 shows the temperature computation. the example instruction code, outlined in example 5-1 , shows the communication flow; also see figure 5-5 for the timing diagram. equation 5-1: bytes to temperature conversion example 5-1: sample instruction code where: t a = ambient temperature (c) upperbyte = t a bit 15 to bit 8 lowerbyte = t a bit 7 to bit 0 temperature t a 0c temperature < 0c t a upperbyte 2 4 lowerbyte 2 4 ? + () = t a 256 upperbyte 2 4 lowerbyte 2 4 ? + () ? = i 2c_start(); // send start command i2c_write (addressbyte & 0xfe); //write command (see section 4.1.4 ?address byte? ) //also, make sure bit 0 is cleared ?0? i2c_write(0x05); // write t a register address i2c_start(); //repeat start i2c_write(addressbyte | 0x01); // read command (see section 4.1.4 ?address byte? ) //also, make sure bit 0 is set ?1? upperbyte = i2c_read(ack); // read 8 bits //and send ack bit lowerbyte = i2c_read(nak); // read 8 bits //and send nak bit i2c_stop(); // send stop command //convert the temperature data //first check flag bits if ((upperbyte & 0x80) == 0x80){ //t a 3 t crit } if ((upperbyte & 0x40) == 0x40){ //t a > t upper } if ((upperbyte & 0x20) == 0x20){ //t a < t lower } upperbyte = upperbyte & 0x1f; //clear flag bits if ((upperbyte & 0x10) == 0x10){ //t a < 0c upperbyte = upperbyte & 0x0f; //clear sign temperature = 256 - (upperbyte x 16 + lowerbyte / 16); }else //t a 3 0c temperature = (upperbyte x 16 + lowerbyte / 16); // temperature = ambient temperature (c) this example routine assumes the variables and i 2 c? communication subroutines are predefined (see appendix a: ?source code? ): mcp9808 ds25095a-page 26 ? 2011 microchip technology inc. figure 5-5: timing diagram for reading +25.25c temperature from the t a register (see section 4.0 ?serial communication? ). sda a c k 0011 a t a pointer 0000 a c k s 2 a 1 a 0 12345678 12345678 scl 0 address byte a c k 0011 a msb data a c k n a k s p 2 a 1 a 0 12345678 12345678 12345678 address byte lsb data r mcp9808 mcp9808 mcp9808 master master w sda scl 101 00000 001 10010 100 note: it is not necessary to select the register pointer if it was set from the previous read/write. ? 2011 microchip technology inc. ds25095a-page 27 mcp9808 5.1.4 manufacturer id register this register is used to identify the manufacturer of the device in order to perform manufacturer-specific operation. the manufacturer id for the mcp9808 is 0x0054 (hexadecimal). figure 5-6: timing diagram for reading the manufacturer id register (see section 4.0 ?serial communication? ). register 5-5: manufacturer id register ? read-only ( address ?0000 0110?b ) r-0 r-0 r-0 r-0 r-0 r-0 r-0 r-0 manufacturer id bit 15 bit 8 r-0 r-1 r-0 r-1 r-0 r-1 r-0 r-0 manufacturer id bit 7 bit 0 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? -n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown bit 15-0 device manufacturer identification bits sda a c k 0011 a manufacturer id pointer 0000 a c k s 2 a 1 a 0 12345678 12345678 scl 0 address byte a c k 0011 a msb data a c k n a k s p 2 a 1 a 0 12345678 12345678 12345678 address byte lsb data r mcp9808 mcp9808 mcp9808 master master w sda scl 110 00000 000 01010 100 note: it is not necessary to select the register pointer if it was set from the previous read/write. mcp9808 ds25095a-page 28 ? 2011 microchip technology inc. 5.1.5 device id and revision register the upper byte of this register is used to specify the device identification and the lower byte is used to specify the device revision. the device id for the mcp9808 is 0x04 (hex). the revision begins with 0x00 (hex) for the first release, with the number being incremented as revised versions are released. figure 5-7: timing diagram for reading device id and device revision register (see section 4.0 ?serial communication? ). register 5-6: device id and device revision ? read-only ( address ?0000 0111?b) r-0 r-0 r-0 r-0 r-0 r-1 r-0 r-0 device id bit 15 bit 8 r-0 r-0 r-0 r-0 r-0 r-0 r-0 r-0 device revision bit 7 bit 0 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? -n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown bit 15-8 device id: bit 15 to bit 8 are used for device id bit 7-0 device revision: bit 7 to bit 0 are used for device revision sda a c k 0011 a device id pointer 0000 a c k s 2 a 1 a 0 12345678 12345678 scl 0 address byte a c k 0011 a msb data a c k n a k s p 2 a 1 a 0 12345678 12345678 12345678 address byte lsb data r mcp9808 mcp9808 mcp9808 master master w sda scl 111 00000 100 00000 000 note: it is not necessary to select the register pointer if it was set from the previous read/write. ? 2011 microchip technology inc. ds25095a-page 29 mcp9808 5.1.6 resolution register this register allows the user to change the sensor resolution (see section 5.2.4 ?temperature resolution? ). the por default resolution is +0.0625c. the selected resolution is also reflected in the capability register (see register 5-2 ). figure 5-8: timing diagram for changing t a resolution to +0.0625c <0000 0011>b (see section 4.0 ?serial communication? ). register 5-7: resolution register ( address ?0000 1000?b) u-0 u-0 u-0 u-0 u-0 u-0 r/w-1 r/w-1 ? ? ? ? ? ? resolution bit 7 bit 0 legend: r = readable bit w = writable bit u = unimplemented bit, read as ?0? -n = value at por ?1? = bit is set ?0? = bit is cleared x = bit is unknown bit 7-2 unimplemented: read as ? 0 ? bit 1-0 resolution bits 00 = +0.5c (t conv = 30 ms typical) 01 = +0.25c (t conv = 65 ms typical) 10 = +0.125c (t conv = 130 ms typical) 11 = +0.0625c (power-up default, t conv = 250 ms typical) sda a c k 0011 a a c k s 2 a 1 a 0 12345678 12345678 scl address byte w mcp9808 mcp9808 a c k p 12345678 data resolution pointer mcp9808 00001 000 00000 011 mcp9808 ds25095a-page 30 ? 2011 microchip technology inc. 5.2 sensor feature description 5.2.1 shutdown mode shutdown mode disables all power consuming activities (including temperature sampling operations) while leaving the serial interface active. this mode is selected by setting bit 8 of config to ? 1 ?. in this mode, the device consumes i shdn . it remains in this mode until bit 8 is cleared to ? 0 ? to enable continuous conversion mode or until power is recycled. the shutdown bit (bit 8) cannot be set to ? 1 ? while the config<7:6> bits (lock bits) are set to ? 1 ?. however, it can be cleared to ? 0 ? or returned to continuous conversion mode while locked. in shutdown mode, all registers can be read or written. however, the serial bus activity increases the shutdown current. in addition, if the device is in shutdown while the alert pin is asserted, the device will retain the active state during shutdown. this increases the shutdown current due to the additional alert output current. 5.2.2 temperature hysteresis (t hyst ) a hysteresis of 0c, +1.5c, +3c or +6c can be selected for the t upper , t lower and t crit temperate boundaries, using bits 10 and 9 of config. the hysteresis applies for decreasing temperature only (hot to cold) or as temperature drifts below the specified limit. the hysteresis bits can not be changed if either of the lock bits (config<7:6) are set to ? 1 ?. the t upper , t lower and t crit boundary conditions are described graphically in figure 5-10 . 5.2.3 alert output configuration the alert output can be enabled by using bit 3 of the config register (alert output control bit) and can be configured as either a comparator output or as an interrupt output mode using bit 0 of config (alert output mode bit). the polarity can also be specified as active-high or active-low using bit 1 of config (alert polarity bit). this is an open-drain output and requires a pull-up resistor. when the ambient temperature increases above the critical temperature limit, the alert output is forced to a comparator output (regardless of config<0>). when the temperature drifts below the critical temperature limit minus hysteresis, the alert output automatically returns to the state specified by config<0> bit. figure 5-9: active-low alert output configuration. the status of the alert output can be read using config<4> (alert output status bit). this bit can not be set to ? 1 ? in shutdown mode. bits 7 and 6 of the config register can be used to lock the t upper , t lower and t crit registers. these bits prevent false triggers at the alert output due to an accidental rewrite to these registers. the alert output can also be used as a critical temper- ature output using bit 2 of config (alert output select bit). when this feature is selected, the alert output becomes a comparator output. in this mode, the interrupt output configuration (alert output mode bit, config<0>) is ignored. 5.2.3.1 comparator mode comparator mode is selected using bit 0 of config. in this mode, the alert output is asserted as active-high or active-low, using bit 1 of config. figure 5-10 shows the conditions that toggle the alert output. if the device enters shutdown mode with asserted alert output, the output remains asserted during shutdown mode. the device must be operating in continuous conversion mode for t conv . the t a vs. t upper , t lower and t crit boundary conditions need to be satisfied in order for the alert output to deassert. comparator mode is useful for thermostat type applications, such as turning on a cooling fan or triggering a system shutdown when the temperature exceeds a safe operating range. mcp9808 alert output r pu v dd ? 2011 microchip technology inc. ds25095a-page 31 mcp9808 5.2.3.2 interrupt mode in interrupt mode, the alert output is asserted as active- high or active-low (depending on the polarity configuration) when t a drifts above or below t upper and t lower limits. the output is deasserted by setting bit 5 (interrupt clear bit) of config. shutting down the device will not reset or deassert the alert output. this mode can not be selected when the alert output is used as a critical temperature output only, using bit 2 of config. this mode is designed for interrupt driven microcontroller-based systems. the microcontroller receiving the interrupt will have to acknowledge the interrupt by setting bit 5 of the config register from the mcp9808. 5.2.4 temperature resolution the mcp9808 is capable of providing temperature data with +0.5c to +0.0625c resolution. the resolu- tion can be selected using the resolution register ( register 5-7 ). it is located at address, ? 00001000?b , and it provides measurement flexibility. a +0.0625c resolution is set as a por default by the factory. table 5-2: temperature conversion time resolution t conv (ms) samples/sec (typical) +0.5c 30 33 +0.25c 65 15 +0.125c 130 7 +0.0625c (power-up default) 250 4 mcp9808 ds25095a-page 32 ? 2011 microchip technology inc. figure 5-10: alert output conditions. t upper t lower alert output t crit t a t upper ? t hyst (active-low) comparator interrupt s/w int. clear critical only t crit ? t hyst 123457 notes alert output boundary conditions comparator interrupt critical t a bits alert output (active-low/high) 15 14 13 1 t a t lower high/low low/high high/low 000 2 t a < t lower ? t hyst low/high low/high high/low 001 3 t a > t upper low/high low/high high/low 010 4 t a t upper ? t hyst high/low low/high high/low 000 5 t a t crit low/high low/high low/high 110 6 when t a t crit , the alert output is forced to comparator mode and the config<0> (alert output mode bit) is ignored until t a < t crit ? t hyst . in the interrupt mode, if the interrupt is not cleared (bit 5 of config), as shown in the diagram at note 6 , then alert will remain asserted at note 7 until the interrupt is cleared by the controller. 7 t a < t crit ? t hyst low/high high/low high/low 010 t lower ? t hyst t lower ? t hyst t upper ? t hyst 13 42 notes: 6 alert output (active-high) comparator interrupt s/w int. clear critical only ? 2011 microchip technology inc. ds25095a-page 33 mcp9808 5.3 summary of power-on default the mcp9808 has an internal power-on reset (por) circuit. if the power supply voltage, v dd , glitches below the v por threshold, the device resets the registers to the power-on default settings. table 5-3 shows the power-on default summary for the temperature sensor registers. table 5-3: power-on reset defaults registers default register data (hexadecimal) power-up default register description address (hexadecimal) register name 0x01 config 0x0000 comparator mode active-low output alert and critical output output disabled alert not asserted interrupt cleared alert limits unlocked critical limit unlocked continuous conversion 0c hysteresis 0x02 t upper 0x0000 0c 0x03 t lower 0x0000 0c 0x04 t crit 0x0000 0c 0x05 t a 0x0000 0c 0x06 manufacturer id 0x0054 0x0054 (hex) 0x07 device id/device revision 0x0400 0x0400 (hex) 0x08 resolution 0x03 0x03 (hex) mcp9808 ds25095a-page 34 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 35 mcp9808 6.0 applications information 6.1 layout considerations the mcp9808 does not require any additional components besides the master controller in order to measure temperature. however, it is recommended that a decoupling capacitor of 0.1 f to 1 f be used between the v dd and gnd pins. a high-frequency ceramic capacitor is recommended. it is necessary for the capacitor to be located as close as possible to the power and ground pins of the device in order to provide effective noise protection. in addition, good pcb layout is key for better thermal conduction from the pcb temperature to the sensor die. for good temperature sensitivity, add a ground layer under the device pins, as shown in figure 6-1 . 6.2 thermal considerations a potential for self-heating errors can exist if the mcp9808 sda, scl and event lines are heavily loaded with pull-ups (high current). typically, the self-heating error is negligible because of the relatively small current consumption of the mcp9808. a temper- ature accuracy error of approximately +0.5c could result from self-heating if the communication pins sink/source the maximum current specified. for example, if the event output is loaded to maximum i ol , equation 6-1 can be used to determine the effect of self-heating. equation 6-1: effect of self-heating at room temperature (t a =+25c) with maximum i dd = 500 a and v dd = 3.6v, the self-heating due to power dissipation t is +0.2c for the dfn-8 package and +0.5c for the tssop-8 package. figure 6-1: dfn package layout (top view). t ja v dd i dd v ol_alert i ol_alert v ol_sda i ol_sda ? + ? + ? () = where: t =t j ? t a t j = junction temperature t a = ambient temperature ja = package thermal resistance v ol_alert, sda = alert and sda output v ol (0.4 v max ) i ol_alert, sda = alert and sda output i ol (3 ma max ) sda scl alert gnd v dd a0 a1 a2 ep9 mcp9808 ds25095a-page 36 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 37 mcp9808 7.0 packaging information 7.1 package marking information legend: xx...x customer-specific information y year code (last digit of calendar year) yy year code (last 2 digits of calendar year) ww week code (week of january 1 is week ?01?) nnn alphanumeric traceability code pb-free jedec designator for matte tin (sn) * this package is pb-free. the pb-free jedec designator ( ) can be found on the outer packaging for this package. note : in the event the full microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information. 3 e 3 e 8-lead dfn (2x3x0.9 mm) example 8-lead msop (3x3 mm) example 9808e 141256 alp 141 25 mcp9808 ds25095a-page 38 ? 2011 microchip technology inc. ! " #$ %! & '(!%&! %( % ")%% % " * & & # "% ( % " + * ) ! % " & "% ,- . /01 / & % # % ! ))%!%% ,21 $ & '! ! )%!%% '$$& % ! 2% & %! % * " ) ' % * $ % % " % %% 133))) & &3 * 4% 55,, & 5&% 6 67 8 6!&( $ 6 9 % ./0 7 : % 9 % "$$ . 0% %* + ,2 7 5 % /0 7 ;"% , + /0 ,# " "5 % + < .. ,# " ";"% , . < . 0% %;"% ( . + 0% %5 % 5 + . 0% % % ,# " " = < < d n e note 1 1 2 exposed pad note 1 2 1 d2 k l e2 n e b a3 a1 a note 2 bottom view top view ) 0 +0 ? 2011 microchip technology inc. ds25095a-page 39 mcp9808 note: for the most current package drawings, please see the microchip packaging specification located at http://www.microchip.com/packaging mcp9808 ds25095a-page 40 ? 2011 microchip technology inc. ! " #$ %! & '(!%&! %( % ")%% % " & ", "%!" &"$ %! "$ %! % # " .&& " + & "% ,- . /01 / & % # % ! ))%!%% ,21 $ & '! ! )%!%% '$$& % ! 2% & %! % * " ) ' % * $ % % " % %% 133))) & &3 * 4% 55,, & 5&% 6 67 8 6!&( $ 6 9 % >./0 7 : % < < " " * * . 9. . % "$$ < . 7 ;"% , /0 " " * ;"% , + /0 7 5 % + /0 2%5 % 5 > 9 2% % 5 .,2 2% ? < 9? 5 "* 9 < + 5 ";"% ( < d n e e1 note 1 1 2 e b a a1 a2 c l1 l ) 0 / ? 2011 microchip technology inc. ds25095a-page 41 mcp9808 note: for the most current package drawings, please see the microchip packaging specification located at http://www.microchip.com/packaging mcp9808 ds25095a-page 42 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 45 mcp9808 software license agreement the software supplied herewith by microchip technology inco rporated (the ?company?) is intended and supplied to you, the company?s customer, for use solely and exclusiv ely with products manufactured by the company. the software is owned by the company and/or its supplier, and is protected under applicable copyright laws. all rights are rese rved. any use in violation of the foregoing restrictions may subject t he user to criminal sanctions under applicabl e laws, as well as to civil liability for the breach of the terms and conditions of this license. this software is provided in an ?as is? condition. no warranties, whether express, implied or statu- tory, including, but not limited to, implied warranties of merchantability and fitness for a particu- lar purpose apply to this software. the company shall not, in any circumstances, be liable for special, incidental or consequential damages, for any reason whatsoever. appendix a: source code /******************************************************************** filename: i2c.c processor: pic18 microcontrollers complier: microchip c18 (for pic18) or c30 (for pic24) company: microchip technology, inc. #include mcp9808 ds25095a-page 46 ? 2011 microchip technology inc. /******************************************************************** * function name: i2c_start * return value: void * parameters: void * description: send i2c start command ********************************************************************/ void i2c_start(void) { pir1bits.sspif = 0; //clear flag while (sspstatbits.bf ); // wait for idle condition sspcon2bits.sen = 1; // initiate start condition while (!pir1bits.sspif) ; // wait for a flag to be set pir1bits.sspif = 0; // clear flag } /******************************************************************** * function name: i2c_repstart * return value: void * parameters: void * description: resend i2c start command * ********************************************************************/ void i2c_repstart(void) { pir1bits.sspif = 0; // clear flag while ( sspstatbits.bf ) ; // wait for idle condition sspcon2bits.rsen = 1; // initiate repeated start condition while (!pir1bits.sspif) ; // wait for a flag to be set pir1bits.sspif = 0; // clear flag } /******************************************************************** * function name: i2c_stop * return value: void * parameters: void * description: send i2c stop command * ********************************************************************/ void i2c_stop(void) { pir1bits.sspif = 0; // clear flag while ( sspstatbits.bf ) ; // wait for idle condition sspcon2bits.pen = 1; // initiate stop condition while (!pir1bits.sspif) ; // wait for a flag to be set pir1bits.sspif = 0; // clear flag } ? 2011 microchip technology inc. ds25095a-page 47 mcp9808 /******************************************************************** * function name: i2c_write * return value: status byte for wcol detection. * parameters: single data byte for i2c2 bus. * description: this routine writes a single byte to the * i2c2 bus. ********************************************************************/ unsigned char i2c_write( unsigned char i2cwritedata ) { pir1bits.sspif = 0; // clear interrupt while ( sspstatbits.bf ) ; // wait for idle condition sspbuf = i2cwritedata; // load sspbuf with i2cwritedata (the value to be transmit- ted) while (!pir1bits.sspif) ; // wait for a flag to be set pir1bits.sspif = 0; // clear flag return ( !sspcon2bits.ackstat ); // function returns '1' if transmission is acknowledged } /******************************************************************** * function name: i2c_read * return value: contents of ssp2buf register * parameters: ack = 1 and nak = 0 * description: read a byte from i2c bus and ack/nak device ********************************************************************/ unsigned char i2c_read( unsigned char ack ) { unsigned char i2creaddata; pir1bits.sspif = 0;// clear interrupt while ( sspstatbits.bf ) ; // wait for idle condition sspcon2bits.rcen = 1; // enable receive mode while (!pir1bits.sspif) ; // wait for a flag to be set pir1bits.sspif = 0;// clear flag i2creaddata = sspbuf; // read sspbuf and put it in i2creaddata if ( ack ) { // if ack=1 sspcon2bits.ackdt = 0; // then transmit an acknowledge } else { sspcon2bits.ackdt = 1; // otherwise transmit a not acknowledge } sspcon2bits.acken = 1; // send acknowledge sequence while (!pir1bits.sspif) ; // wait for a flag to be set pir1bits.sspif = 0;// clear flag return( i2creaddata ); // return the value read from sspbuf } mcp9808 ds25095a-page 48 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 49 mcp9808 appendix b: revision history revision a (october 2011) ? original release of this document. mcp9808 ds25095a-page 50 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 51 mcp9808 product identification system to order or obtain information, e. g., on pricing or delivery, refer to the factory or the listed sales office . device: mcp9808: digital temperature sensor mcp9808t: digital temperature sensor (tape and reel) temperature range: e = -40c to +125c package: mc = plastic dual flat no-lead (dfn) 2x3, 8-lead ms = plastic micro small outline (msop), 8-lead part no. -x /xx package temperature range device examples: a) MCP9808-E/mc: extended temperature 8ld dfn package. b) MCP9808-E/ms: extended temperature 8ld msop package. c) mcp9808t-e/mc: tape and reel, extended temperature 8ld dfn package. d) mcp9808t-e/ms: tape and reel, extended temperature 8ld msop package. x tape and reel alternate pinout and/or mcp9808 ds25095a-page 52 ? 2011 microchip technology inc. notes: ? 2011 microchip technology inc. ds25095a-page 53 information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. it is your responsibility to ensure that your application meets with your specifications. microchip makes no representations or warranties of any kind whether express or implied, written or oral, statutory or otherwise, related to the information, including but not limited to its condition, quality, performance, merchantability or fitness for purpose . microchip disclaims all liability arising from this information and its use. use of microchip devices in life support and/or safety applications is entirely at the buyer?s risk, and the buyer agrees to defend, indemnify and hold harmless microchip from any and all damages, claims, suits, or expenses resulting from such use. no licenses are conveyed, implicitly or otherwise, under any microchip intellectual property rights. trademarks the microchip name and logo, the microchip logo, dspic, k ee l oq , k ee l oq logo, mplab, pic, picmicro, picstart, pic 32 logo, rfpic and uni/o are registered trademarks of microchip technology incorporated in the u.s.a. and other countries. filterlab, hampshire, hi-tech c, linear active thermistor, mxdev, mxlab, seeval and the embedded control solutions company are registered trademarks of microchip technology incorporated in the u.s.a. analog-for-the-digital age, app lication maestro, chipkit, chipkit logo, codeguard, dspicdem, dspicdem.net, dspicworks, dsspeak, ecan, economonitor, fansense, hi-tide, in-circuit serial programming, icsp, mindi, miwi, mpasm, mplab certified logo, mplib, mplink, mtouch, omniscient code generation, picc, picc-18, picdem, picdem.net, pickit, pictail, real ice, rflab, select mode, total endurance, tsharc, uniwindriver, wiperlock and zena are trademarks of microchip technology incorporated in the u.s.a. and other countries. sqtp is a service mark of microchip technology incorporated in the u.s.a. all other trademarks mentioned herein are property of their respective companies. ? 2011, microchip technology incorporated, printed in the u.s.a., all rights reserved. printed on recycled paper. isbn: 978-1-61341-739-3 note the following details of the code protection feature on microchip devices: ? microchip products meet the specification cont ained in their particular microchip data sheet. ? microchip believes that its family of products is one of the most secure families of its kind on the market today, when used i n the intended manner and under normal conditions. ? there are dishonest and possibly illegal methods used to breach the code protection feature. all of these methods, to our knowledge, require using the microchip produc ts in a manner outside the operating specif ications contained in microchip?s data sheets. most likely, the person doing so is engaged in theft of intellectual property. ? microchip is willing to work with the customer who is concerned about the integrity of their code. ? neither microchip nor any other semiconduc tor manufacturer can guarantee the security of their code. code protection does not mean that we are guaranteeing the product as ?unbreakable.? code protection is constantly evolving. we at microchip are co mmitted to continuously improvin g the code protection features of our products. attempts to break microchip?s code protection feature may be a violation of the digital millennium copyright act. if such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that act. microchip received iso/ts-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in chandler and tempe, arizona; gresham, oregon and design centers in california and india. the company?s quality system processes and procedures are for its pic ? mcus and dspic ? dscs, k ee l oq ? code hopping devices, serial eeproms, microperipherals, nonvolatile memory and analog products. in addition, microchip?s quality system for the design and manufacture of development systems is iso 9001:2000 certified. ds25095a-page 54 ? 2011 microchip technology inc. americas corporate office 2355 west chandler blvd. chandler, az 85224-6199 tel: 480-792-7200 fax: 480-792-7277 technical support: http://www.microchip.com/ support web address: www.microchip.com atlanta duluth, ga tel: 678-957-9614 fax: 678-957-1455 boston westborough, ma tel: 774-760-0087 fax: 774-760-0088 chicago itasca, il tel: 630-285-0071 fax: 630-285-0075 cleveland independence, oh tel: 216-447-0464 fax: 216-447-0643 dallas addison, tx tel: 972-818-7423 fax: 972-818-2924 detroit farmington hills, mi tel: 248-538-2250 fax: 248-538-2260 indianapolis noblesville, in tel: 317-773-8323 fax: 317-773-5453 los angeles mission viejo, ca tel: 949-462-9523 fax: 949-462-9608 santa clara santa clara, ca tel: 408-961-6444 fax: 408-961-6445 toronto mississauga, ontario, canada tel: 905-673-0699 fax: 905-673-6509 asia/pacific asia pacific office suites 3707-14, 37th floor tower 6, the gateway harbour city, kowloon hong kong tel: 852-2401-1200 fax: 852-2401-3431 australia - sydney tel: 61-2-9868-6733 fax: 61-2-9868-6755 china - beijing tel: 86-10-8569-7000 fax: 86-10-8528-2104 china - chengdu tel: 86-28-8665-5511 fax: 86-28-8665-7889 china - chongqing tel: 86-23-8980-9588 fax: 86-23-8980-9500 china - hangzhou tel: 86-571-2819-3187 fax: 86-571-2819-3189 china - hong kong sar tel: 852-2401-1200 fax: 852-2401-3431 china - nanjing tel: 86-25-8473-2460 fax: 86-25-8473-2470 china - qingdao tel: 86-532-8502-7355 fax: 86-532-8502-7205 china - shanghai tel: 86-21-5407-5533 fax: 86-21-5407-5066 china - shenyang tel: 86-24-2334-2829 fax: 86-24-2334-2393 china - shenzhen tel: 86-755-8203-2660 fax: 86-755-8203-1760 china - wuhan tel: 86-27-5980-5300 fax: 86-27-5980-5118 china - xian tel: 86-29-8833-7252 fax: 86-29-8833-7256 china - xiamen tel: 86-592-2388138 fax: 86-592-2388130 china - zhuhai tel: 86-756-3210040 fax: 86-756-3210049 asia/pacific india - bangalore tel: 91-80-3090-4444 fax: 91-80-3090-4123 india - new delhi tel: 91-11-4160-8631 fax: 91-11-4160-8632 india - pune tel: 91-20-2566-1512 fax: 91-20-2566-1513 japan - yokohama tel: 81-45-471- 6166 fax: 81-45-471-6122 korea - daegu tel: 82-53-744-4301 fax: 82-53-744-4302 korea - seoul tel: 82-2-554-7200 fax: 82-2-558-5932 or 82-2-558-5934 malaysia - kuala lumpur tel: 60-3-6201-9857 fax: 60-3-6201-9859 malaysia - penang tel: 60-4-227-8870 fax: 60-4-227-4068 philippines - manila tel: 63-2-634-9065 fax: 63-2-634-9069 singapore tel: 65-6334-8870 fax: 65-6334-8850 taiwan - hsin chu tel: 886-3-5778-366 fax: 886-3-5770-955 taiwan - kaohsiung tel: 886-7-536-4818 fax: 886-7-330-9305 taiwan - taipei tel: 886-2-2500-6610 fax: 886-2-2508-0102 thailand - bangkok tel: 66-2-694-1351 fax: 66-2-694-1350 europe austria - wels tel: 43-7242-2244-39 fax: 43-7242-2244-393 denmark - copenhagen tel: 45-4450-2828 fax: 45-4485-2829 france - paris tel: 33-1-69-53-63-20 fax: 33-1-69-30-90-79 germany - munich tel: 49-89-627-144-0 fax: 49-89-627-144-44 italy - milan tel: 39-0331-742611 fax: 39-0331-466781 netherlands - drunen tel: 31-416-690399 fax: 31-416-690340 spain - madrid tel: 34-91-708-08-90 fax: 34-91-708-08-91 uk - wokingham tel: 44-118-921-5869 fax: 44-118-921-5820 worldwide sales and service 08/02/11 |
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