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typical application circuit and functional diagram appear at end of data sheet. pin configurations continued at end of data sheet. cell phones san/nas servers notebooks satellite radio 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 inter - rupt 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 i 2 c 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. applications features 400khz, +6v-tolerant i 2 c 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 +denotes a lead(pb)-free/rohs-compliant package. *ep = exposed pad. part inputs interrupt mask open- drain outputs push-pull outputs max7324 8 yes 8 max7325 up to 8 up to 8 8 max7326 4 yes 12 max7327 up to 4 up to 4 12 part temp range pin- package max7324aeg+ -40c to +125c 24 qsop MAX7324ATG+ -40c to +125c 24 tqfn-ep* (4mm x 4mm) tqfn (4mm x 4mm) + top view max7324 19 20 21 22 1 2 3 4 5 6 18 17 16 15 14 13 23 24 12 11 10 9 8 7 scl v+ sda int ad2 i0 i1 i2 i3 i4 i5 ad0 o15 o13 o12 rst o11 o10 o8 o9 gnd i6 i7 o14 exposed pad 19-3785; rev 1; 5/14 selector guide ordering information pin confgurations max7324 i 2 c port expander with eight push-pull outputs and eight inputs evaluation kit available
(all voltages referenced to gnd.) supply voltage v+ ................................................... -0.3v to +6v scl, sda, ad0, ad2, rst , int , i0Ci7 ................... -0.3v to +6v o8Co15 ....................................................... -0.3v to (v+ + 0.3v) o8Co15 output current...... .......................................... ...25ma sda sink current .............................................................. 10ma int sink current ................................................................. 10ma total v+ current ................................................................. 50ma total gnd current ........................................................... 100ma continuous power dissipation qsop (derate 9.5mw/c over t a = +70c) ............... 761.9mw tqfn (derate 20.8mw/c over t a = +70c) ......... 1666.7mw operating temperature range ......................... -40c to +125c junction temperature ...................................................... +150c storage temperature range ............................ -65c to +150c lead temperature (soldering, 10s) ................................. +300c (v+ = +1.71v to +5.5v, t a = -40c to +125c, unless otherwise noted. typical values are at v+ = +3.3v, t a = +25c.) (note 1) parameter symbol conditions min typ max units operating supply voltage v + t a = -40c to +125c 1.71 5.50 v power-on reset voltage v por v+ falling 1.6 v standby current (interface idle) i stb scl and sda and other digital inputs at v+ 0.6 1.9 a supply current (interface running) i + f scl = 400khz; other digital inputs at v+ 23 55 a input high-voltage sda, scl, ad0, ad2, rst , i0Ci7 v ih v+ < 1.8v 0.8 x v+ v v+ 1.8 0.7 x v+ input low-voltage sda, scl, ad0, ad2, rst , i0Ci7 v il v+ < 1.8v 0.2 x v+ v v+ 1.8 0.3 x v+ input leakage current sda, scl, ad0, ad2, rst , i0Ci7 i ih , i il sda, scl, ad0, ad2, rst , i0Ci7 at v+ or gnd -0.2 +0.2 a input capacitance sda, scl, ad0, ad2, rst , i0Ci7 10 pf output low voltage o8Co15 v ol v+ = +1.71v, i sink = 5ma (qsop) 90 180 mv v+ = +1.71v, i sink = 5ma (tqfn) 90 230 v+ = +2.5v, i sink = 10ma (qsop) 110 210 v+ = +2.5v, i sink = 10ma (tqfn) 110 260 v+ = +3.3v, i sink = 15ma (qsop) 130 230 v+ = +3.3v, i sink = 15ma (tqfn) 130 280 v+ = +5v, i sink = 20ma (qsop) 140 250 v+ = +5v, i sink = 20ma (tqfn) 140 300 output high voltage o8Co15 v oh v+ = +1.71v, i source = 2ma v+ - 250 v+ - 30 mv v+ = +2.5v, i source = 5ma v+ - 360 v+ - 70 v+ = +3.3v, i source = 5ma v+ - 260 v+ - 100 v+ = +5v, i source = 10ma v+ - 360 v+ - 120 output low-voltage sda v olsda i sink = 6ma 250 mv output low-voltage int v olint i sink = 5ma 130 250 mv port input pullup resistor r pu 25 40 55 k w maxim integrated 2 dc electrical characteristics stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress rating s 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 ab solute maximum rating conditions for extended periods may affect device reliability. absolute maximum ratings www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
note 1: all parameters are tested at t a = +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 v il of the scl signal) to bridge the undefined region of scl's falling edge. note 3: guaranteed by design. note 4: c b = total capacitance of one bus line in pf. t r and t f measured between 0.3 x v+ and 0.7 x v+. i sink 6ma. note 5: input filters on the sda and scl inputs suppress noise spikes less than 50ns. (v+ = +1.71v to +5.5v, t a = -40c to +125c, unless otherwise noted. typical values are at v+ = +3.3v, t a = +25c.) (note 1) (v+ = +1.71v to +5.5v, t a = -40c to +125c, unless otherwise noted. typical values are at v+ = +3.3v, t a = +25c.) (note 1) parameter symbol conditions min typ max units serial-clock frequency f scl 400 khz bus free time between a stop and a start condition t buf 1.3 s hold time (repeated) start condition t hd,sta 0.6 s repeated start condition setup time t su,sta 0.6 s stop condition setup time t su,sto 0.6 s data hold time t hd,dat (note 2) 0.9 s data setup time t su,dat 100 ns scl clock low period t low 1.3 s scl clock high period t high 0.7 s rise time of both sda and scl signals, receiving t r (notes 3, 4) 20 + 0.1c b 300 ns fall time of both sda and scl signals, receiving t f (notes 3, 4) 20 + 0.1c b 300 ns fall time of sda transmitting t f,tx (notes 3, 4) 20 + 0.1c b 250 ns pulse width of spike suppressed t sp (note 5) 50 ns capacitive load for each bus line c b (note 3) 400 pf rst pulse width t w 500 ns rst rising to start condition setup time t rst 1 s parameter symbol conditions min typ max units port-output data valid t ppv c l 100pf 4 s port-input setup time t psu c l 100pf 0 s port-input hold time t ph c l 100pf 4 s int input data valid time t iv c l 100pf 4 s int reset delay time from stop t ip c l 100pf 4 s int reset delay time from acknowledge t ir c l 100pf 4 s maxim integrated 3 timing characteristics port and interrupt int timing characteristics www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
(t a = +25c, unless otherwise noted.) pin name function qsop tqfn 1 22 int active-low interrupt output. int is an open-drain output. 2 23 rst active-low reset input. drive rst low to clear the 2-wire interface. 3, 21 24, 18 ad2, ad0 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). 4C11 1C8 i0Ci7 input ports. i0 to i7 are cmos-logic inputs. 12 9 gnd ground 13C20 10C17 08C015 output ports. o8Co15 are push-pull outputs rated at 20ma. 22 19 scl i 2 c-compatible serial clock input 23 20 sda i 2 c-compatible serial data i/o 24 21 v + positive supply voltage. bypass v+ to gnd with a ceramic capacitor of at least 0.047f. ep ep exposed paddle. connect exposed pad to gnd. output-voltage high vs. temperature temperature ( c) output-voltage high (v) max7324 toc04 -40 -25 -10 5 20 35 50 65 80 95 110 125 0 1 2 3 4 5 6 v+ = +3.3v i source = 5ma v+ = +5.0v i source = 10ma v+ = +2.5v i source = 5ma v+ = +1.71v i source = 2ma output-voltage low vs. temperature temperature ( c) output-voltage low (v) max7324 toc03 -40 -25 -10 5 20 35 50 65 80 95 110 125 0 0.05 0.10 0.15 0.20 0.25 v+ = +3.3v i sink = 15ma v+ = +5.0v i sink = 20ma v+ = +2.5v i sink = 10ma v+ = +1.71v i sink = 5ma supply current vs. temperature temperature ( c) supply current (a) max7324 toc02 -40 -25 -10 5 20 35 50 65 80 95 110 125 0 10 20 30 40 50 60 v+ = +3.3v v+ = +5.0v v+ = +2.5v v+ = +1.71v f scl = 400khz standby current vs. temperature temperature ( c) standby current (a) max7324 toc01 -40 -25 -10 5 20 35 50 65 80 95 110 125 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 v+ = +3.3v v+ = +5.0v v+ = +2.5v v+ = +1.71v f scl = 0khz maxim integrated 4 pin description typical operating characteristics www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
detailed description max7324 C max7327 family comparison the max7324Cmax7327 family consists of four pin-compatible, 16-port expanders that integrate the function of the max7320 and one of either the max7319, max7321, max7322, or max7323. 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 +6v. the max7324 is set to two of 32 i 2 c slave addresses (see tables 2 and 3) using address select inputs ad0 and ad2, and is accessed over an i 2 c 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 addresses 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. table 1. max7319 C max7329 family comparison part i 2 c slave address inputs input interrupt mask open- drain outputs push- pull outputs configuration 16-port expanders max7324 101xxxx and 110xxxx 8 yes 8 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. max7325 up to 8 up to 8 8 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 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 logic- high. transition flags identify which open-drain port inputs have changed (even if only for a transient) since the ports were last read. maxim integrated 5 www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
table 1. max7319 C max7329 family comparison (continued) part i 2 c slave address inputs input interrupt mask open- drain outputs push- pull outputs configuration max7326 101xxxx and 110xxxx 4 yes 12 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. max7327 up to 4 up to 4 12 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. 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 logic- high. transition flags identify which open-drain port inputs have changed (even if only for a transient) since the ports were last read. 8-port expanders max7319 110xxxx 8 yes input-only versions: 8 input ports with programmable latching transition detection interrupt and selectable pullups. max7320 101xxxx 8 output-only versions: 8 push-pull outputs with selectable power-up default levels. max7321 110xxxx up to 8 up to 8 i/o versions: 8 open-drain i/o ports with latching transition detection interrupt and selectable pullups. max7322 110xxxx 4 yes 4 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. maxim integrated 6 www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
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). 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 i 2 c slave address selection inputs, ad0 and ad1 (see table 3). 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 v por (1.6v max), the por circuit releases the registers and 2-wire interface for normal operation. when v+ drops below v por , the max7324 resets all register contents to the por defaults (tables 2 and 3). rst input the rst input voids any i 2 c transaction involving the max7324, forcing the max7324 into the i 2 c 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. 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 i 2 c 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 i 2 c transmission. ad0 and ad2 initially appear to be connected to v+ or gnd. this is important because the address selection determines which inputs have pullups applied. however, at power-up, the i 2 c sda and scl bus interface lines are high impedance at the inputs of every device (master or slave) connected to the bus, includ - ing the max7324. this is guaranteed as part of the i 2 c 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 i0Ci3, table 1. max7319 C max7329 family comparison (continued) part i 2 c slave address inputs input interrupt mask open- drain outputs push- pull outputs configuration max7323 110xxxx up to 4 up to 4 4 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. max7328 max7329 0100xxx 0111xxx up to 8 up to 8 pcf8574-, pcf8574a-compatible versions: 8 open-drain i/o ports with nonlatching transition detection interrupt and pullups on all ports. maxim integrated 7 www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
and uses ad2 to select whether pullups are enabled for ports i4Ci7. 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 i 2 c configuration, where sda and scl are pulled up to v+ by the external i 2 c pullups. there are circumstances where the assumption that sda = scl = v+ on power-up is not truefor example, in applications in which there is legitimate bus activity during power-up. also, if sda and scl are terminat - ed 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 connect - ed 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 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 i 2 c transmission (to any device, not neces - sarily 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 i 2 c 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. 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 table 2. max7324 address map for inputs i0 C i7 pin connection device address 40k w input pullup enabled ad2 ad0 a6 a5 a4 a3 a2 a1 a0 i7 i6 i5 i4 i3 i2 i1 i0 scl gnd 1 1 0 0 0 0 0 y y y y scl v+ 1 1 0 0 0 0 1 y y y y y y y y scl scl 1 1 0 0 0 1 0 y y y y y y y y scl sda 1 1 0 0 0 1 1 y y y y y y y y sda gnd 1 1 0 0 1 0 0 y y y y sda v+ 1 1 0 0 1 0 1 y y y y y y y y sda scl 1 1 0 0 1 1 0 y y y y y y y y sda sda 1 1 0 0 1 1 1 y y y y y y y y gnd gnd 1 1 0 1 0 0 0 gnd v+ 1 1 0 1 0 0 1 y y y y gnd scl 1 1 0 1 0 1 0 y y y y gnd sda 1 1 0 1 0 1 1 y y y y v+ gnd 1 1 0 1 1 0 0 y y y y v+ v+ 1 1 0 1 1 0 1 y y y y y y y y v+ scl 1 1 0 1 1 1 0 y y y y y y y y v+ sda 1 1 0 1 1 1 1 y y y y y y y y maxim integrated 8 www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
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 less-important inputs. the transition flags indicate whether a permanent or transient change has occurred on any input since the max7324 was last accessed. table 3. max7324 address map for outputs o8 C o15 pin connection device address outputs power-up default ad2 ad0 a6 a5 a4 a3 a2 a1 a0 o15 o14 o13 o12 o11 o10 o9 o8 scl gnd 1 0 1 0 0 0 0 1 1 1 1 0 0 0 0 scl v+ 1 0 1 0 0 0 1 1 1 1 1 1 1 1 1 scl scl 1 0 1 0 0 1 0 1 1 1 1 1 1 1 1 scl sda 1 0 1 0 0 1 1 1 1 1 1 1 1 1 1 sda gnd 1 0 1 0 1 0 0 1 1 1 1 0 0 0 0 sda v+ 1 0 1 0 1 0 1 1 1 1 1 1 1 1 1 sda scl 1 0 1 0 1 1 0 1 1 1 1 1 1 1 1 sda sda 1 0 1 0 1 1 1 1 1 1 1 1 1 1 1 gnd gnd 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 gnd v+ 1 0 1 1 0 0 1 0 0 0 0 1 1 1 1 gnd scl 1 0 1 1 0 1 0 0 0 0 0 1 1 1 1 gnd sda 1 0 1 1 0 1 1 0 0 0 0 1 1 1 1 v+ gnd 1 0 1 1 1 0 0 1 1 1 1 0 0 0 0 v+ v+ 1 0 1 1 1 0 1 1 1 1 1 1 1 1 1 v+ scl 1 0 1 1 1 1 0 1 1 1 1 1 1 1 1 v+ sda 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 maxim integrated 9 www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
serial interface serial addressing the max7324 operates as a slave that sends and receives data through an i 2 c 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). figure 3. bit transfer figure 2. start and stop conditions figure 1. 2-wire serial-interface timing details sda scl data line stable; data valid change of data allowed sda scl start condition stop condition s p scl sda t r t f t buf start condition stop condition repeated start condition start condition t su,sto t hd,sta t su,sta t hd,dat t su,dat t low t high t hd,sta maxim integrated 10 www.maximintegrated.com max7324 i 2 c 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 gener - ates 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 condi - tion. slave address the max7324 has two different 7-bit slave addresses (tables 2 and 3). the addresses are different for commu - nicating 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 (i0Ci7) or 1, 0, and 1 (o8Co15). 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 i 2 c bus. accessing the max7324 the max7324 is accessed though an i 2 c interface. the max7324 provides two different 7-bit slave addresses for either the eight input ports (i0Ci7) or the eight push-pull ports (o8Co15). 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 repeat - edly returns the status of the eight output ports, read back as inputs. a multibyte read (more than 2 bytes before the i 2 c 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. figure 5. slave address figure 4. acknowledge sda scl 1 a5 a3 a2 a1 a0 a4 r/w msb lsb ack scl sda by transmitter clock pulse for acknowledgement start condition sda by receiver 1 2 8 9 s maxim integrated 11 www.maximintegrated.com max7324 i 2 c 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 i 2 c 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 2 c acknowledge bit (the acknowledge bit for the i 2 c slave address in the case of a single-byte or 2-byte read). a multibyte read (more than 2 bytes before the i 2 c 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 cur - rent 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. figure 6. reading input ports of the max7324 (1 data byte) scl max7324 slave address s a p 1 ports acknowledge from max7324 acknowledge from master port snapshot t iv t ph t ir a i0 i1 i2 i3 i4 i5 i6 i7 d0 d1 d2 d3 d4 d5 d6 d7 port snapshot t ps t ip int output r/w s = start condition a = acknowledge p = stop condition int remains high until stop condition maxim integrated 12 www.maximintegrated.com max7324 i 2 c 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 condi - tion (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. figure 8. reading output ports of the max7324 figure 7. reading input ports of the max7324 (2 data bytes) scl max7324 slave address s a p 1 acknowledge from max7324 port snapshot data port snapshot taken a p0 p1 p2 p3 data 1 p4 p5 p6 p7 d0 d1 d2 d3 d4 d5 d6 d7 port snapshot taken acknowledge from master r/w scl max7324 slave address s a p 1 ports acknowledge from max7324 acknowledge from master port snapshot t iv t ph t ir a i0 i1 i2 i3 i4 i5 i6 i7 d0 d1 d2 d3 d4 d5 d6 d7 port snapshot t ps t ip f0 f1 f2 f3 f4 f5 f6 f7 d7 d6 d5 d4 d3 d2 d1 d0 a port snapshot flag int output r/w s = start condition a = acknowledge p = stop condition int remains high until stop condition maxim integrated 13 www.maximintegrated.com max7324 i 2 c 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). 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). figure 10. writing to the output ports of the max7324 figure 9. writing to the input ports of the max7324 scl sda start condition acknowledge from slave slave address s 0 1 2 3 4 5 6 7 8 a a a t pv data 1 data 2 data 2 valid data 1 valid write to port data out from port acknowledge from slave acknowledge from slave t pv data to port data to port r/w scl sda start condition r/w slave address s 0 1 2 3 4 5 6 7 8 a a a t pv data 1 data 2 t pv data to interrupt mask data to interrupt mask maxim integrated 14 www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
applications information port input and i 2 c interface level translation from higher or lower logic voltages sda, scl, ad0, ad2, rst , int , and i0Ci7 are overvoltage protected to +6v. this allows the max7324 to operate from a lower supply voltage, such as +3.3v, while the i 2 c 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 i 2 c interface and/or some of the input ports i0Ci7 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+. 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. 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 ports 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 i0Ci7 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 i0Ci7 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. driving led loads when driving leds from one of the eight output ports, o8Co15, 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, r led . figure 12. max7324 input port structure figure 11. max7324 output port structure i0?i7 pullup enable input 40k? v+ v+ max7324 output v+ gnd gnd v+ o8?o15 max7324 maxim integrated 15 www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
set the port output low to light the led. choose the resistor value according to the following formula: r led = (v supply - v led - v ol ) / iled where: r led is the resistance of the resistor in series with the led ( ? ). v supply is the supply voltage used to drive the led (v). v led is the forward voltage of the led (v). v ol is the output low voltage of the max7324 when sinking i led (v). i led is the desired operating current of the led (a). for example, to operate a 2.2v red led at 10ma from +5v supply: r led = (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 loads 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. maxim integrated 16 www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
package type package code outline no. land pattern no. 16 qsop e24+1 21-0055 90-0172 16 tqfn-ep t2444+3 21-0139 90-0022 top view 24 23 22 21 20 19 18 17 1 2 3 4 5 6 7 8 v+ sda scl ad0 015 014 013 012 max7324 qsop rst ad2 i2 i0 i1 i3 i4 16 15 9 10 011 010 i5 i6 14 13 11 12 o9 o8 i7 gnd int + max7324 i2 i7 i6 i5 i4 o11 o10 09 08 o15 o14 013 012 v+ 3.3v c scl scl sda ad0 i1 i0 sda i3 gnd input input ad2 int input input input input input input output output output output rst int rst i 2 c control o9 o8 o11 o10 o12 o13 o14 o15 i1 i0 i3 i2 i4 i5 i6 i7 int i/o ports power- on reset input filter rst sda scl ad2 ad0 n max7324 maxim integrated 17 chip information process: bicmos 3lqrqjxudwlrqvfrqwlqxhg typical application circuit functional diagram package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. www.maximintegrated.com max7324 i 2 c port expander with eight push-pull outputs and eight inputs
revision number revision date description pages changed 0 10/06 initial release 1 5/14 no /v opns; removed automotive reference from applications section; updated packaging information 1 ? 2014 maxim integrated products, inc. 18 revision history maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and specifcations without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max7324 i 2 c port expander with eight push-pull outputs and eight inputs for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com.

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