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| 19-3785; Rev 0; 10/06 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs General Description The MAX7324 2-wire serial-interfaced peripheral features 16 I/O ports that are divided into eight push-pull outputs and eight inputs. Each input features selectable internal pullups, overvoltage protection to +6V, and transition detection with an interrupt output. All input ports are continuously monitored for state changes (transition detection). The interrupt is latched, allowing detection of transient changes. Any combination of inputs can be selected using the interrupt mask to assert the INT output. When the MAX7324 is subsequently accessed through the serial interface, any pending interrupt is cleared. The push-pull outputs are rated to sink 20mA and are capable of driving LEDs. The RST input clears the serial interface, terminating any I2C communication to or from the MAX7324. The MAX7324 uses two address inputs with four-level logic to allow 16 I 2 C slave addresses. The slave address also enables or disables internal 40k pullups in groups of four ports. The MAX7324 is one device in a family of pin-compatible port expanders with a choice of input ports, open-drain I/O ports, and push-pull output ports (see Table 1). The MAX7324 is available in 24-pin QSOP and TQFN packages, and is specified over the -40C to +125C automotive temperature range. I2C Features 400kHz, +6V-Tolerant Serial Interface +1.71V to 5.5V Operating Voltage Eight Push-Pull Outputs Eight Input Ports with Maskable, Latching Transition Detection Input Ports are Overvoltage Protected to +6V Transient Changes are Latched, Allowing Detection Between Read Operations INT Output Alerts Change on Any Selection of Inputs AD0 and AD2 Inputs Select from 16 Slave Addresses Low 0.6A Standby Current -40C to +125C Temperature Range MAX7324 Ordering Information PART MAX7324AEG+ MAX7324ATG+ TEMP RANGE -40C to +125C -40C to +125C PINPACKAGE 24 QSOP 24 TQFN-EP* (4mm x 4mm) PKG CODE E24-1 T2444-3 Applications Cell Phones SAN/NAS Servers Notebooks Automotive Satellite Radio +Denotes lead-free package. *EP = Exposed paddle. Selector Guide PART MAX7324 MAX7325 INPUTS 8 Up to 8 4 Up to 4 INTERRUPT MASK Yes -- Yes -- OPENPUSH-PULL DRAIN OUTPUTS OUTPUTS -- Up to 8 -- Up to 4 8 8 12 12 Pin Configurations O15 O13 O12 14 O14 O11 13 12 O10 11 O9 10 O8 TOP VIEW 18 SCL 19 SDA 20 V+ 21 INT 22 RST 23 AD2 24 + 1 I0 AD0 17 16 15 MAX7326 MAX7327 MAX7324 EXPOSED PADDLE 2 I1 3 I2 4 I3 5 I4 6 I5 9 8 7 GND I7 I6 Typical Application Circuit and Functional Diagram appear at end of data sheet. TQFN (4mm x 4mm) Pin Configurations continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) Supply Voltage V+....................................................-0.3V to +6V SCL, SDA, AD0, AD2, RST, INT, I0-I7......................-0.3V to +6V O8-O15................................................-0.3V to (V+ + 0.3V) O8-O15 Output Current.............................................25mA SDA Sink Current ............................................................... 10mA INT Sink Current..................................................................10mA Total V+ Current..................................................................50mA Total GND Current ...........................................................100mA Continuous Power Dissipation 24-Pin QSOP (derate 9.5mW/C over TA = +70C) ..761.9mW 24-Pin TQFN (derate 20.8mW/C over TA = +70C) ............................................................1666.7mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (V+ = +1.71V to +5.5V, TA = -40C to +125C, unless otherwise noted. Typical values are at V+ = +3.3V, TA = +25C.) (Note 1) PARAMETER Operating Supply Voltage Power-On Reset Voltage Standby Current (Interface Idle) Supply Current (Interface Running) Input High-Voltage SDA, SCL, AD0, AD2, RST, I0-I7 Input Low-Voltage SDA, SCL, AD0, AD2, RST, I0-I7 Input Leakage Current SDA, SCL, AD0, AD2, RST, I0-I7 Input Capacitance SDA, SCL, AD0, AD2, RST, I0-I7 V+ = +1.71V, ISINK = 5mA (QSOP) V+ = +1.71V, ISINK = 5mA (TQFN) V+ = +2.5V, ISINK = 10mA (QSOP) Output Low Voltage O8-O15 VOL V+ = +2.5V, ISINK = 10mA (TQFN) V+ = +3.3V, ISINK = 15mA (QSOP) V+ = +3.3V, ISINK = 15mA (TQFN) V+ = +5V, ISINK = 20mA (QSOP) V+ = +5V, ISINK = 20mA (TQFN) V+ = +1.71V, ISOURCE = 2mA Output High Voltage O8-O15 VOH V+ = +2.5V, ISOURCE = 5mA V+ = +3.3V, ISOURCE = 5mA V+ = +5V, ISOURCE = 10mA Output Low-Voltage SDA Output Low-Voltage INT Port Input Pullup Resistor VOLSDA VOLINT RPU ISINK = 6mA ISINK = 5mA 25 130 40 SYMBOL V+ VPOR ISTB I+ VIH VIL IIH, IIL V+ falling SCL and SDA and other digital inputs at V+ fSCL = 400kHz; other digital inputs at V+ V+ < 1.8V V+ 1.8 V+ < 1.8V V+ 1.8 SDA, SCL, AD0, AD2, RST, I0-I7 at V+ or GND -0.2 10 90 90 110 110 130 130 140 140 V+ - 250 V+ - 30 V+ - 360 V+ - 70 V+ - 260 V+ - 100 V+ - 360 V+ - 120 250 250 55 mV mV k mV 180 230 210 260 230 280 250 300 mV 0.8 x V+ 0.7 x V+ 0.2 x V+ 0.3 x V+ +0.2 0.6 23 CONDITIONS TA = -40C to +125C MIN 1.71 TYP MAX 5.50 1.6 1.9 55 UNITS V V A A V V A pF 2 _______________________________________________________________________________________ I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs PORT AND INTERRUPT INT TIMING CHARACTERISTICS (V+ = +1.71V to +5.5V, TA = -40C to +125C, unless otherwise noted. Typical values are at V+ = +3.3V, TA = +25C.) (Note 1) PARAMETER Port-Output Data Valid Port-Input Setup Time Port-Input Hold Time INT Input Data Valid Time INT Reset Delay Time from STOP INT Reset Delay Time from Acknowledge SYMBOL tPPV tPSU tPH tIV tIP tIR CL 100pF CL 100pF CL 100pF CL 100pF CL 100pF CL 100pF 0 4 4 4 4 CONDITIONS MIN TYP MAX 4 UNITS s s s s s s MAX7324 TIMING CHARACTERISTICS (V+ = +1.71V to +5.5V, TA = -40C to +125C, unless otherwise noted. Typical values are at V+ = +3.3V, TA = +25C.) (Note 1) PARAMETER Serial-Clock Frequency Bus Free Time Between a STOP and a START Condition Hold Time (Repeated) START Condition Repeated START Condition Setup Time STOP Condition Setup Time Data Hold Time Data Setup Time SCL Clock Low Period SCL Clock High Period Rise Time of Both SDA and SCL Signals, Receiving Fall Time of Both SDA and SCL Signals, Receiving Fall Time of SDA Transmitting Pulse Width of Spike Suppressed Capacitive Load for Each Bus Line RST Pulse Width RST Rising to START Condition Setup Time SYMBOL fSCL tBUF tHD,STA tSU,STA tSU,STO tHD,DAT tSU,DAT tLOW tHIGH tR tF tF,TX tSP Cb tW tRST (Notes 3, 4) (Notes 3, 4) (Notes 3, 4) (Note 5) (Note 3) 500 1 (Note 2) 100 1.3 0.7 20 + 0.1Cb 20 + 0.1Cb 20 + 0.1Cb 50 400 300 300 250 1.3 0.6 0.6 0.6 0.9 CONDITIONS MIN TYP MAX 400 UNITS kHz s s s s s ns s s ns ns ns ns pF ns s Note 1: All parameters are tested at TA = +25C. Specifications over temperature are guaranteed by design. Note 2: A master device must provide a hold time of at least 300ns for the SDA signal (referred to VIL of the SCL signal) to bridge the undefined region of SCL's falling edge. Note 3: Guaranteed by design. Note 4: Cb = total capacitance of one bus line in pF. tR and tF measured between 0.3 x V+ and 0.7 x V+. ISINK 6mA. Note 5: Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns. _______________________________________________________________________________________ 3 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Typical Operating Characteristics (TA = +25C, unless otherwise noted.) STANDBY CURRENT vs. TEMPERATURE MAX7324 toc01 SUPPLY CURRENT vs. TEMPERATURE fSCL = 400kHz 50 SUPPLY CURRENT (A) 40 30 20 10 0 V+ = +5.0V MAX7324 toc02 MAX7324 toc04 2.0 1.8 1.6 STANDBY CURRENT (A) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 V+ = +1.71V V+ = +2.5V V+ = +3.3V V+ = +5.0V fSCL = 0kHz 60 V+ = +3.3V V+ = +2.5V V+ = +1.71V -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) OUTPUT-VOLTAGE LOW vs. TEMPERATURE MAX7324 toc03 OUTPUT-VOLTAGE HIGH vs. TEMPERATURE 6 5 OUTPUT-VOLTAGE HIGH (V) 4 3 2 1 0 V+ = +3.3V ISOURCE = 5mA V+ = +2.5V ISOURCE = 5mA V+ = +1.71V ISOURCE = 2mA V+ = +5.0V ISOURCE = 10mA 0.25 V+ = +5.0V ISINK = 20mA V+ = +3.3V ISINK = 15mA 0.15 OUTPUT-VOLTAGE LOW (V) 0.20 0.10 V+ = +2.5V ISINK = 10mA V+ = +1.71V ISINK = 5mA 0.05 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) Pin Description PIN QSOP 1 2 3, 21 4-11 12 13-20 22 23 24 -- TQFN 22 23 24, 18 1-8 9 10-17 19 20 21 EP NAME INT RST AD2, AD0 I0-I7 GND 08-015 SCL SDA V+ EP FUNCTION Active-Low Interrupt Output. INT is an open-drain output. Active-Low Reset Input. Drive RST low to clear the 2-wire interface. Address Inputs. Select device slave address with AD0 and AD2. Connect AD0 and AD2 to either GND, V+, SCL, or SDA to give four logic combinations (see Tables 2 and 3). Input Ports. I0 to I7 are CMOS-logic inputs. Ground Output Ports. O8-O15 are push-pull outputs rated at 20mA. I2C-Compatible Serial Clock Input I2C-Compatible Serial Data I/O Positive Supply Voltage. Bypass V+ to GND with a ceramic capacitor of at least 0.047F. Exposed Paddle. Connect exposed pad to GND. 4 _______________________________________________________________________________________ I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs Detailed Description MAX7324-MAX7327 Family Comparison The MAX7324-MAX7327 family consists of four pincompatible, 16-port expanders that integrate the function of the MAX7320 and one of either the MAX7319, MAX7321, MAX7322, or MAX7323. The MAX7324 is set to two of 32 I2C slave addresses (see Tables 2 and 3) using address select inputs AD0 and AD2, and is accessed over an I2C serial interface up to 400kHz. The eight outputs and eight inputs have different slave addresses. The eight push-pull outputs have the 101xxxx addresses and the eight inputs have the adresses with 110xxxx. The RST input clears the serial interface in case of a bus lockup, terminating any serial transaction to or from the MAX7324. The input ports offer latching transition detection feature. All input ports are continuously monitored for changes. An input change sets 1 of 8 flag bits that identify the changed input(s). All flags are cleared upon a subsequent read or write transaction to the MAX7324. MAX7324 Functional Overview The MAX7324 is a general-purpose port expander operating from a +1.71V to +5.5V supply with eight push-pull outputs and eight CMOS input ports that are overvoltage protected to +5.5V. Table 1. MAX7319-MAX7329 Family Comparison PART I2C INPUT SLAVE INPUTS INTERRUPT MASK ADDRESS OPENDRAIN OUTPUTS PUSHPULL OUTPUTS CONFIGURATION 16-PORT EXPANDERS 8 inputs and 8 push-pull outputs version: 8 input ports with programmable latching transition detection interrupt and selectable pullups. 8 push-pull outputs with selectable default logic levels. Offers maximum versatility for automatic input monitoring. An interrupt mask selects which inputs cause an interrupt on transitions, and transition flags identify which inputs have changed (even if only for a transient) since the ports were last read. 8 I/O and 8 push-pull outputs version: 8 open-drain I/O ports with latching transition detection interrupt and selectable pullups. 8 push-pull outputs with selectable default logic levels. MAX7325 Up to 8 -- Up to 8 8 Open-drain outputs can level shift the logic-high state to a higher or lower voltage than V+ using external pullup resistors, but pullups draw current when output is low. Any open-drain port can be used as an input by setting the open-drain output to logichigh. Transition flags identify which open-drain port inputs have changed (even if only for a transient) since the ports were last read. MAX7324 8 Yes -- 8 101xxxx and 110xxxx _______________________________________________________________________________________ 5 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Table 1. MAX7319-MAX7329 Family Comparison (continued) PART I2C INPUT SLAVE INPUTS INTERRUPT MASK ADDRESS OPENDRAIN OUTPUTS PUSHPULL OUTPUTS CONFIGURATION 4 input-only, 12 push-pull output versions: 4 input ports with programmable latching transition detection interrupt and selectable pullups. 12 push-pull outputs with selectable default logic levels. Offers maximum versatility for automatic input monitoring. An interrupt mask selects which inputs cause an interrupt on transitions, and transition flags identify which inputs have changed (even if only for a transient) since the ports were last read. 4 I/O, 12 push-pull output versions: 4 open-drain I/O ports with latching transition detection interrupt and selectable pullups. 12 push-pull outputs with selectable default logic levels. MAX7327 Up to 4 -- Up to 4 12 Open-drain outputs can level shift the logic-high state to a higher or lower voltage than V+ using external pullup resistors, but pullups draw current when output is low. Any open-drain port can be used as an input by setting the open-drain output to logichigh. Transition flags identify which open-drain port inputs have changed (even if only for a transient) since the ports were last read. Input-only versions: 8 input ports with programmable latching transition detection interrupt and selectable pullups. Output-only versions: 8 push-pull outputs with selectable power-up default levels. I/O versions: 8 open-drain I/O ports with latching transition detection interrupt and selectable pullups. 4 input-only, 4 output-only versions: 4 input ports with programmable latching transition detection interrupt and selectable pullups. 4 push-pull outputs with selectable power-up default levels. MAX7326 4 Yes -- 12 101xxxx and 110xxxx 8-PORT EXPANDERS MAX7319 110xxxx 8 Yes -- -- MAX7320 101xxxx -- -- -- 8 MAX7321 110xxxx Up to 8 -- Up to 8 -- MAX7322 110xxxx 4 Yes -- 4 6 _______________________________________________________________________________________ I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Table 1. MAX7319-MAX7329 Family Comparison (continued) PART I2C INPUT INPUTS INTERRUPT SLAVE ADDRESS MASK OPENDRAIN OUTPUTS PUSHPULL OUTPUTS CONFIGURATION 4 I/O, 4 output-only versions: 4 open-drain I/O ports with latching transition detection interrupt and selectable pullups. 4 push-pull outputs with selectable power-up default levels. PCF8574-, PCF8574A-compatible versions: 8 open-drain I/O ports with nonlatching transition detection interrupt and pullups on all ports. MAX7323 110xxxx Up to 4 -- Up to 4 4 MAX7328 MAX7329 0100xxx 0111xxx Up to 8 -- Up to 8 -- A latching interrupt output, INT, is programmed to flag input data changes on input ports through an interrupt mask register. By default, data changes on any input port force INT to a logic-low. The interrupt output INT and all transition flags are cleared when the MAX7324 is next accessed through the serial interface. Internal pullup resistors to V+ are selected by the address select inputs, AD0 and AD2. Pullups are enabled on the input ports in groups of four (see Table 2). RST Input The RST input voids any I2C transaction involving the MAX7324, forcing the MAX7324 into the I2C STOP condition. A reset does not affect the interrupt output (INT). Standby Mode When the serial interface is idle, the MAX7324 automatically enters standby mode, drawing minimal supply current. Initial Power-Up On power-up, the transition detection logic is reset, and INT is deasserted. The interrupt mask register is set to 0xFF, enabling the interrupt output for transitions on all eight input ports. The transition flags are cleared to indicate no data changes. The power-up default states of the eight push-pull outputs are set according to the I2C slave address selection inputs, AD0 and AD1 (see Table 3). Slave Address, Power-Up Default Logic Levels, and Input Pullup Selection Address inputs AD0 and AD2 determine the MAX7324 slave address and select which inputs have pullup resistors. Pullups are enabled on the input ports in groups of four (see Table 2). The MAX7324 slave address is determined on each I2C transmission, regardless of whether the transmission is actually addressing the MAX7324. The MAX7324 distinguishes whether address inputs AD0 and AD2 are connected to SDA or SCL instead of fixed logic levels V+ or GND during this transmission. This means that the MAX7324 slave address can be configured dynamically in the application without cycling the device supply. On initial power-up, the MAX7324 cannot decode the address inputs AD0 and AD2 fully until the first I2C transmission. AD0 and AD2 initially appear to be connected to V+ or GND. This is important because the Power-On Reset The MAX7324 contains an integral power-on-reset (POR) circuit that ensures all registers are reset to a known state on power-up. When V+ rises above VPOR (1.6V max), the POR circuit releases the registers and 2-wire interface for normal operation. When V+ drops below VPOR, the MAX7324 resets all register contents to the POR defaults (Tables 2 and 3). _______________________________________________________________________________________ 7 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Table 2. MAX7324 Address Map for Inputs I0-I7 PIN CONNECTION AD2 SCL SCL SCL SCL SDA SDA SDA SDA GND GND GND GND V+ V+ V+ V+ AD0 GND V+ SCL SDA GND V+ SCL SDA GND V+ SCL SDA GND V+ SCL SDA A6 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 A5 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 DEVICE ADDRESS A4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 A2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 A1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 A0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 I7 Y Y Y Y Y Y Y Y -- -- -- -- Y Y Y Y I6 Y Y Y Y Y Y Y Y -- -- -- -- Y Y Y Y 40k INPUT PULLUP ENABLED I5 Y Y Y Y Y Y Y Y -- -- -- -- Y Y Y Y I4 Y Y Y Y Y Y Y Y -- -- -- -- Y Y Y Y I3 -- Y Y Y -- Y Y Y -- Y Y Y -- Y Y Y I2 -- Y Y Y -- Y Y Y -- Y Y Y -- Y Y Y I1 -- Y Y Y -- Y Y Y -- Y Y Y -- Y Y Y I0 -- Y Y Y -- Y Y Y -- Y Y Y -- Y Y Y address selection determines which inputs have pullups applied. However, at power-up, the I2C SDA and SCL bus interface lines are high impedance at the inputs of every device (master or slave) connected to the bus, including the MAX7324. This is guaranteed as part of the I2C specification. Therefore, address inputs AD0 and AD2 that are connected to SDA or SCL during power-up appear to be connected to V+. The pullup selection logic uses AD0 to select whether pullups are enabled for ports I0-I3, and uses AD2 to select whether pullups are enabled for ports I4-I7. The rule is that a logic-high SDA, or SCL connection selects the pullups, while a logic-low deselects the pullups (Table 2). The pullup configuration is correct on power-up for a standard I2C configuration, where SDA and SCL are pulled up to V+ by the external I2C pullups. There are circumstances where the assumption that SDA = SCL = V+ on power-up is not true--for example, in applications in which there is legitimate bus activity during power-up. Also, if SDA and SCL are terminated with pullup resistors to a different supply voltage than the MAX7324's supply voltage, and if that pullup supply rises later than the MAX7324's supply, then SDA or SCL may appear at power-up to be connected to GND. In such applications, use the four address combinations that are selected by connecting address inputs AD0 and AD2 to V+ or GND (shown in bold in Tables 2 8 and 3). These selections are guaranteed to be correct at power-up, independent of SDA and SCL behavior. If one of the other 12 address combinations is used, an unexpected combination of pullups might be asserted until the first I2C transmission (to any device, not necessarily the MAX7324) is put on the bus. Port Inputs Port inputs switch at CMOS logic levels as determined by the expander's supply voltage, and are overvoltage tolerant to +6V, independent of the device's supply voltage. Port-Input Transition Detection All eight input ports are monitored for changes since the expander was last accessed through the serial interface. The state of the input ports is stored in an internal "snapshot" register for transition monitoring. The snapshot is continuously compared with the actual input conditions, and if a change is detected for any port input, then an internal transition flag is set for that port. The eight port inputs are sampled (internally latched into the snapshot register) and the old transition flags cleared during the I2C acknowledge of every MAX7324 read and write access. The previous port transition flags are read through the serial interface as the second byte of a 2-byte read sequence. _______________________________________________________________________________________ I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Table 3. MAX7324 Address Map for Outputs O8-O15 PIN CONNECTION AD2 SCL SCL SCL SCL SDA SDA SDA SDA GND GND GND GND V+ V+ V+ V+ AD0 GND V+ SCL SDA GND V+ SCL SDA GND V+ SCL SDA GND V+ SCL SDA A6 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 A5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 DEVICE ADDRESS A4 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 A3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 A2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 A1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 A0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 O15 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 O14 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 OUTPUTS POWER-UP DEFAULT O13 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 O12 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 O11 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 O10 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 O9 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 O8 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 A long read sequence (more than 2 bytes) can be used to poll the expander continuously without the overhead of resending the slave address. If more than 2 bytes are read from the expander, the expander repeatedly returns the 2 bytes of input port data followed by the transition flags. The inputs are repeatedly resampled and the transition flags repeatedly reset for each pair of bytes read. All changes that occur during a long read sequence are detected and reported. The MAX7324 includes an 8-bit interrupt mask register that selects which inputs generate an interrupt upon change. Each input's transition flag is set when its input changes, independent of the interrupt mask register settings. The interrupt mask register allows the processor to be interrupted for critical events, while the inputs and the transition flags can be polled periodically to detect less critical events. The INT output is not reasserted during a read sequence to avoid recursive reentry into an interrupt service routine. Instead, if a data change occurs that would normally cause the INT output to be set, the INT assertion is delayed until the STOP condition. INT is not reasserted upon a STOP condition if the changed input data is read before the STOP occurs. The INT logic ensures that unnecessary interrupts are not asserted, yet data changes are detected and reported no matter when the change occurs. Transition-Detection Masks The transition detection logic incorporates a transition flag and an interrupt mask bit for each input port. The eight transition flags can be read through the serial interface, and the 8-bit interrupt mask is set through the serial interface. Each port's transition flag is set when that port's input changes, and the change flag remains set even if the input returns to its original state. The port's interrupt mask determines whether a change on that input port generates an interrupt. Enable interrupts for high-priority inputs using the interrupt mask. The interrupt allows the system to respond quickly to changes on these inputs. Poll the MAX7324 periodically to monitor lessimportant inputs. The transition flags indicate whether a permanent or transient change has occurred on any input since the MAX7324 was last accessed. _______________________________________________________________________________________ 9 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Serial Interface Serial Addressing The MAX7324 operates as a slave that sends and receives data through an I2C interface. The interface uses a serial-data line (SDA) and a serial-clock line (SCL) to achieve bidirectional communication between master(s) and slave(s). The master initiates all data transfers to and from the MAX7324 and generates the SCL clock that synchronizes the data transfer (Figure 1). SDA operates as both an input and an open-drain output. A pullup resistor, typically 4.7k, is required on SDA. SCL operates only as an input. A pullup resistor, typically 4.7k, is required on SCL if there are multiple masters on the 2-wire interface, or if the master in a single-master system has an open-drain SCL output. Each transmission consists of a START condition sent by a master, followed by the MAX7324's 7-bit slave address plus R/W bit, 1 or more data bytes, and finally a STOP condition (Figure 2). START and STOP Conditions Both SCL and SDA remain high when the interface is not busy. A master signals the beginning of a transmission with a START (S) condition by transitioning SDA from high to low while SCL is high. When the master has finished communicating with the slave, the master issues a STOP (P) condition by transitioning SDA from low to high while SCL is high. The bus is then free for another transmission (Figure 2). Bit Transfer One data bit is transferred during each clock pulse. The data on SDA must remain stable while SCL is high (Figure 3). SDA tSU,STA tHD,DAT tHIGH tBUF tHD,STA tSU,STO tLOW tSU,DAT SCL tHD,STA tR START CONDITION tF REPEATED START CONDITION STOP CONDITION START CONDITION Figure 1. 2-Wire Serial-Interface Timing Details SDA SCL SDA S P STOP CONDITION SCL DATA LINE STABLE; CHANGE OF DATA DATA VALID ALLOWED START CONDITION Figure 2. START and STOP Conditions Figure 3. Bit Transfer 10 ______________________________________________________________________________________ I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs Acknowledge The acknowledge bit is a clocked 9th bit the recipient uses to acknowledge receipt of each byte of data (Figure 4). Each byte transferred effectively requires 9 bits. The master generates the 9th clock pulse, and the recipient pulls down SDA during the acknowledge clock pulse, such that the SDA line is stable low during the high period of the clock pulse. When the master is transmitting to the MAX7324, the MAX7324 generates the acknowledge bit because the MAX7324 is the recipient. When the MAX7324 is transmitting to the master, the master generates the acknowledge bit because the master is the recipient. The master does not generate an acknowledge prior to issuing a stop condition. Slave Address The MAX7324 has two different 7-bit slave addresses (Tables 2 and 3). The addresses are different for communicating to either the eight push-pull outputs or the eight inputs. The eighth bit following the 7-bit slave address is the R/W bit. It is low for a write command and high for a read command. The first (A6), second (A5), and third (A4) bits of the MAX7324 slave address are always 1, 1, and 0 (I0-I7) or 1, 0, and 1 (O8-O15). Connect AD0 and AD2 to GND, V+, SDA, or SCL to select the slave address bits A3, A2, A1, and A0. The MAX7324 has 16 possible slave address pairs (Tables 2 and 3), allowing up to 16 MAX7324 devices on an I2C bus. Accessing the MAX7324 The MAX7324 is accessed though an I2C interface. The MAX7324 provides two different 7-bit slave addresses for either the eight input ports (I0-I7) or the eight pushpull ports (O8-O15). See Tables 2 and 3. A single-byte read from the input ports of the MAX7324 returns the status of the eight ports and clears both the internal transition flags and the INT output. A single-byte read from the output ports of the MAX7324 returns the status of the eight output ports, read back as inputs. A 2-byte read from the input ports of the MAX7324 returns the status of the eight ports (as for a single-byte read), followed by the transition flags. The internal transition flags and the INT output are cleared when the MAX7324 acknowledges the slave address byte, but the previous transition flag data is sent as the second byte. A 2-byte read from the output ports of the MAX7324 repeatedly returns the status of the eight output ports, read back as inputs. A multibyte read (more than 2 bytes before the I2C STOP bit) from the input ports of the MAX7324 repeatedly returns the port data, alternating with the transition flags. As the input data is resampled for each transmission, and the transition flags are reset each time, a multibyte read continuously returns the current data and identifies any changing input ports. MAX7324 START CONDITION SCL SDA BY TRANSMITTER SDA BY RECEIVER S 1 2 CLOCK PULSE FOR ACKNOWLEDGEMENT 8 9 Figure 4. Acknowledge . SDA 1 MSB SCL A5 A4 A3 A2 A1 A0 LSB R/W ACK Figure 5. Slave Address ______________________________________________________________________________________ 11 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs If a port input data change occurs during the read sequence, INT is reasserted during the I2C STOP bit. The MAX7324 does not generate another interrupt during a single-byte or multibyte read. Input-port data is sampled during the preceding I 2C acknowledge bit (the acknowledge bit for the I2C slave address in the case of a single-byte or 2-byte read). A multibyte read (more than 2 bytes before the I 2C STOP bit) from the output ports of the MAX7324 repeatedly returns the status of the eight output ports, read back as inputs. A single-byte write to the input ports of the MAX7324 sets the interrupt mask register and clears both the internal transition flags and INT output. A single-byte write to the output ports of the MAX7324 sets the logic state of all eight ports. A multibyte write to the input ports of the MAX7324 sets the interrupt mask register repeatedly. A multibyte write to the output ports of the MAX7324 repeatedly sets the logic state of all eight ports. Reading from the MAX7324 A read from the input ports of the MAX7324 starts with the master transmitting the input ports' slave address with the R/W bit set to high. The MAX7324 acknowledges the slave address and samples the ports during the acknowledge bit. INT deasserts during the slave address acknowledge. Typically, the master reads 1 or 2 bytes from the MAX7324 with each byte being acknowledged by the master upon reception with the exception of the last byte. When the master reads one byte from the open-drain ports of the MAX7324 and subsequently issues a STOP condition (Figure 6), the MAX7324 transmits the current port data, clears the transition flags, and resets the transition detection. INT deasserts during the slave acknowledge. The new snapshot data is the current port data transmitted to the master, and therefore, port changes occuring during the transmission are detected. INT remains high until the STOP condition. MAX7324 ACKNOWLEDGE FROM MAX7324 I7 I6 I5 I4 I3 I2 I1 I0 ACKNOWLEDGE FROM MASTER S MAX7324 SLAVE ADDRESS R/W 1 A D7 D6 D5 D4 D3 D2 D1 D0 A P PORT SNAPSHOT PORT SNAPSHOT SCL tPH PORTS tIV INT OUTPUT tIR INT REMAINS HIGH UNTIL STOP CONDITION S = START CONDITION P = STOP CONDITION A = ACKNOWLEDGE tPS tIP Figure 6. Reading Input Ports of the MAX7324 (1 Data Byte) 12 ______________________________________________________________________________________ I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs When the master reads 2 bytes from the output ports of the MAX7324 and subsequently issues a STOP condition (Figure 7), the MAX7324 transmits the current port data, followed by the transition flags. The transition flags are then cleared, and transition detection is reset. INT deasserts during the slave acknowledge. The new snapshot data is the current port data transmitted to the master, and therefore, port transitions occuring during the transmission are detected. INT remains high until the STOP condition. When the master reads more than 2 data bytes, the input port data alternates with the transition flag. A read from the output ports of the MAX7324 starts with the master transmitting the ports' slave address with the R/W bit set high. The MAX7324 acknowledges the slave address and samples the logic state of the output ports during the acknowledge bit. The master can read one or more bytes from the output ports of the MAX7324, and then issues a STOP condition (Figure 8). The MAX7324 transmits the current port data, read back from the actual port outputs (not the port output latches) during the acknowledge. If a port is forced to a logic state other than its programmed state, the readback reflects this. If driving a capacitive load, the readback port level verification algorithms may need to take the RC rise/fall time into account. Typically, the master reads one byte from the ouput ports of the MAX7324, then issues a STOP condition (Figure 8). However, the master can read two or more bytes from the output ports of the MAX7324, and then issues a STOP condition. In this case, the MAX7324 resamples the port outputs during each acknowledge and transmits the new data each time. MAX7324 ACKNOWLEDGE FROM MAX7324 I7 I6 I5 I4 I3 I2 I1 I0 F7 F6 F5 F4 F3 F2 F1 F0 FLAG ACKNOWLEDGE FROM MASTER S MAX7324 SLAVE ADDRESS R/W 1 A D7 D6 D5 D4 D3 D2 D1 D0 A D7 D6 D5 D4 D3 D2 D1 D0 A P PORT SNAPSHOT PORT SNAPSHOT PORT SNAPSHOT SCL tPH PORTS tIV INT OUTPUT tPS tIR INT REMAINS HIGH UNTIL STOP CONDITION S = START CONDITION P = STOP CONDITION A = ACKNOWLEDGE tIP Figure 7. Reading Input Ports of the MAX7324 (2 Data Bytes) PORT SNAPSHOT DATA ACKNOWLEDGE FROM MAX7324 S MAX7324 SLAVE ADDRESS R/W SCL 1 A P7 P6 P5 P4 P3 DATA 1 P2 P1 P0 D7 D6 D5 D4 D3 D2 D1 D0 A P ACKNOWLEDGE FROM MASTER PORT SNAPSHOT TAKEN PORT SNAPSHOT TAKEN Figure 8. Reading Output Ports of the MAX7324 ______________________________________________________________________________________ 13 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs Writing to the MAX7324 A write to the input ports of the MAX7324 starts with the master transmitting the group's slave address with the R/W bit set low. The MAX7324 acknowledges the slave address and samples the ports during the acknowledge bit. INT deasserts during the slave acknowledge. The master can now transmit one or more bytes of data. The MAX7324 acknowledges these subsequent bytes of data and updates the interrupt mask register with each new byte until the master issues a STOP condition (Figure 9). MAX7324 A write to the output ports of the MAX7324 starts with the master transmitting the group's slave address with the R/W bit set low. The MAX7324 acknowledges the slave address and samples the ports during the acknowledge bit. The master can now transmit one or more bytes of data. The MAX7324 acknowledges these subsequent bytes of data and updates the corresponding group's ports with each new byte until the master issues a STOP condition (Figure 10). SCL 1 2 3 4 5 6 7 8 DATA TO INTERRUPT MASK 0 R/W tPV tPV A DATA 1 A DATA TO INTERRUPT MASK DATA 2 A SLAVE ADDRESS SDA S START CONDITION Figure 9. Writing to the Input Ports of the MAX7324 SCL 1 2 3 4 5 6 7 8 DATA TO PORT 0 R/W A ACKNOWLEDGE FROM SLAVE DATA 1 A ACKNOWLEDGE FROM SLAVE DATA TO PORT DATA 2 A ACKNOWLEDGE FROM SLAVE SLAVE ADDRESS SDA S START CONDITION WRITE TO PORT DATA OUT FROM PORT DATA 1 VALID tPV tPV DATA 2 VALID Figure 10. Writing to the Output Ports of the MAX7324 14 ______________________________________________________________________________________ I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs Applications Information Port Input and I2C Interface Level Translation from Higher or Lower Logic Voltages SDA, SCL, AD0, AD2, RST, INT, and I0-I7 are overvoltage protected to +6V. This allows the MAX7324 to operate from a lower supply voltage, such as +3.3V, while the I2C interface and/or any of the eight input ports are driven from a higher logic level, such as +5V. The MAX7324 can operate from a higher supply voltage, such as +3V, while the I2C interface and/or some of the input ports I0-I7 are driven from a lower logic level, such as +2.5V. For V+ < 1.8V, apply a minimum voltage of 0.8 x V+ to assert a logic-high on any input. For V+ 1.8V, apply a voltage of 0.7 x V+ to assert a logic-high. For example, a MAX7324 operating from a +5V supply may not recognize a +3.3V nominal logic high. One solution for input level translation is to drive the MAX7324 inputs from open-drain outputs. Use a pullup resistor to V+ or a higher supply to ensure a high logic voltage greater than 0.7 x V+. Each of the eight output ports has protection diodes to V+ and GND. When a port output is driven to a voltage higher than V+ or lower than GND, the appropriate protection diode clamps the output to a diode drop above V+ or below GND. When the MAX7324 is powered down (V+ = 0), every output port's protection diodes to V+ and GND continue to appear as a diode clamp from each output to GND (Figure 11). Each of the input ports I0-I7 has a protection diode to GND (Figure 12). When a port input is driven to a voltage lower than GND, the protection diode clamps the voltage to a diode drop below GND. Each of the eight input ports I0-I7 also has a 40k (typ) pullup resistor that can be enabled or disabled. When a port input is driven to a voltage higher than V+, the body diode of the pullup enable switch conducts and the 40k pullup resistor is enabled. When the MAX7324 is powered down (V+ = 0), every input port appears as a 40k resistor in series with a diode connected to ground. Input ports are protected to +6V under any of these circumstances. MAX7324 Port Output Signal Level Translation RST, SCL, SDA, AD0, and AD2 remain high impedance with up to +6V asserted on them when the MAX7324 is powered down (V+ = 0). The MAX7324 can therefore be used in hot-swap applications. Driving LED Loads When driving LEDs from one of the eight output ports, O8-O15, a resistor must be fitted in series with the LED to limit the LED current to no more than 20mA. Connect the LED cathode to the MAX7324 port, and the LED anode to V+ through the series current-limiting resistor, RLED. V+ V+ PULLUP ENABLE O8-O15 INPUT V+ V+ MAX7324 MAX7324 40k I0-I7 OUTPUT GND GND Figure 11. MAX7324 Output Port Structure Figure 12. MAX7324 Input Port Structure ______________________________________________________________________________________ 15 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Set the port output low to light the LED. Choose the resistor value according to the following formula: RLED = (VSUPPLY - VLED - VOL) / ILED where: RLED is the resistance of the resistor in series with the LED (). VSUPPLY is the supply voltage used to drive the LED (V). VLED is the forward voltage of the LED (V). VOL is the output low voltage of the MAX7324 when sinking ILED (V). ILED is the desired operating current of the LED (A). For example, to operate a 2.2V red LED at 10mA from +5V supply: RLED = (5 - 2.2 - 0.1) / 0.01 = 270 Driving Load Currents Higher than 20mA The MAX7324 can be used to drive loads such as relays that draw more than 20mA by paralleling outputs. Use at least one output per 20mA of load current; for example, a 5V 330mW relay draws 66mA, and therefore, requires four paralleled outputs. Any combination of outputs can be used as part of a load-sharing design because any combination of ports can be set or cleared at the same time by writing to the MAX7324. Do not exceed a total sink current of 100mA for the device. Protect the MAX7324 from the negative voltage transient generated when switching off inductive loads (such as relays) by connecting a reverse-biased diode across the inductive load. Choose the peak current for the diode to be greater than the inductive load's operating current. Power-Supply Considerations The MAX7324 operates with a supply voltage of +1.71V to +5.5V over the -40C to +125C temperature range. Bypass the supply to GND with a ceramic capacitor of at least 0.047F as close as possible to the device. For the TQFN version, additionally connect the exposed pad to GND. 16 ______________________________________________________________________________________ I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs Functional Diagram Typical Application Circuit 3.3V MAX7324 C AD0 AD2 O15 O14 O13 O12 O11 O10 O9 O8 I7 I6 I5 I4 I3 I2 I1 I0 INT RST POWERON RESET N SCL SDA RST INT SCL SDA RST INT V+ SCL SDA INPUT FILTER I 2C CONTROL I/O PORTS MAX7324 O15 O14 013 012 O11 O10 09 08 I7 I6 I5 I4 I3 I2 I1 I0 OUTPUT OUTPUT OUTPUT OUTPUT INPUT INPUT INPUT INPUT INPUT INPUT INPUT INPUT MAX7324 AD0 AD2 GND Pin Configurations (continued) PROCESS: BiCMOS TOP VIEW + INT 1 RST 2 AD2 3 I0 4 I1 5 I2 6 I3 7 I4 8 I5 9 I6 10 I7 11 GND 12 24 V+ 23 SDA 22 SCL Chip Information MAX7324 21 AD0 20 015 19 014 18 013 17 012 16 011 15 010 14 O9 13 O8 QSOP ______________________________________________________________________________________ 17 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm 21-0139 E 1 2 18 ______________________________________________________________________________________ 24L QFN THIN.EPS I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) MAX7324 PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm 21-0139 E 2 2 ______________________________________________________________________________________ 19 I2C Port Expander with Eight Push-Pull Outputs and Eight Inputs MAX7324 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) QSOP.EPS PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 F 1 1 Revision History All pages changed at Rev 2. Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. |
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