MAX7324AEG+ ,I²C Port Expander with Eight Push-Pull Outputs and Eight InputsApplications● Cell Phones ● NotebooksSelector Guide● SAN/NAS ● Satellite RadioOPEN-● ServersINTERRU ..
MAX7324AEG+ ,I²C Port Expander with Eight Push-Pull Outputs and Eight Inputsfeatures selectable internal ● Eight Push-Pull Outputspullups, overvoltage protection to +6V, and t ..
MAX7325AEG+ ,I2C Port Expander with 8 Push-Pull and 8 Open-Drain I/Osfeatures ● 400kHz I C Serial Interface16 I/O ports. Ports are divided into eight push-pull outputs ..
MAX7325AEG+ ,I2C Port Expander with 8 Push-Pull and 8 Open-Drain I/OsFeatures2The MAX7325 2-wire serial-interfaced peripheral
MAX7325ATG+ ,I2C Port Expander with 8 Push-Pull and 8 Open-Drain I/OsApplicationsSelector Guide● Cell Phones ● Notebooks● SAN/NAS ● Satellite Radio OPEN-INTERRUPT PUSH- ..
MAX7325ATG+T ,I2C Port Expander with 8 Push-Pull and 8 Open-Drain I/OsEVALUATION KIT AVAILABLE2MAX7325 I C Port Expander with 8 Push-Pull and 8 Open-Drain I/Os
MB54502PFV ,Low noise amplifier (2 circuits)applications such as handy phones and car phones. Both of the amplifiers achieve low current consu ..
MB54609PFV ,Quadrature Modulator IC (With 1.0 GHz Up-converter)FUJITSU SEMICONDUCTORDS04-23509-1EDATA SHEETASSP for TelephoneBIPOLARQuadrature Modulator IC(With ..
MB6021A ,SINGLE CHIP CODEC WITH FILTERSFUJITSU hTCRoirLECTR()NTCS 31.5 D, " 37u=17aa 001.71.55 =1 "hu
April 1990
Edition 3.0
DA TA ..
MB6021AP ,SINGLE CHIP CODEC WITH FILTERSFUNCTIONAL DESCRIPTION
The simplified
MB6022 , Product Summary Prototyping Kits
MB6022 , Product Summary Prototyping Kits
MAX7324AEG+
I²C Port Expander with Eight Push-Pull Outputs and Eight Inputs
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 DescriptionThe 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 I2C communication to or from
the MAX7324.
The MAX7324 uses two address inputs with four-level
logic to allow 16 I2C slave addresses. The slave address also enables or disables internal 40kΩ 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 -40°C to +125°C
automotive temperature range.
Applications
Features●400kHz, +6V-Tolerant I2C 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 0.6µA Standby Current●-40°C to +125°C Temperature Range
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
PARTINPUTSINTERRUPT
MASK
OPEN-
DRAIN
OUTPUTS
PUSH-PULL
OUTPUTSMAX73248Yes—8
MAX7325Up to 8—Up to 88
MAX73264Yes—12
MAX7327Up to 4—Up to 412
PARTTEMP RANGEPIN-
PACKAGEMAX7324AEG+-40°C to +125°C24 QSOP
MAX7324ATG+-40°C to +125°C24 TQFN-EP*
(4mm x 4mm)
TQFN (4mm x 4mm)TOP VIEW
MAX7324234561716151413
SCL
SDA
INT
AD2I1I2I3I4I5
AD0O15O13O12
RST
O11
O10
GND
O14
EXPOSED PAD
MAX7324I2C Port Expander with
Eight Push-Pull Outputs and Eight Inputs
Selector Guide
Ordering Information
Pin Conigurations
EVALUATION KIT AVAILABLE
(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 DissipationQSOP (derate 9.5mW/°C over TA = +70°C) ...............761.9mWTQFN (derate 20.8mW/°C over TA = +70°C) .........1666.7mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range ............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
(V+ = +1.71V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, TA = +25°C.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSOperating Supply VoltageV+TA = -40°C to +125°C1.715.50V
Power-On Reset VoltageVPORV+ falling1.6V
Standby Current (Interface Idle)ISTBSCL and SDA and other digital inputs at V+0.61.9µA
Supply Current
(Interface Running)I+fSCL = 400kHz; other digital inputs at V+2355µA
Input High-Voltage
SDA, SCL, AD0, AD2, RST, I0–I7VIH
V+ < 1.8V0.8 x V+V+ ≥ 1.80.7 x V+
Input Low-Voltage
SDA, SCL, AD0, AD2, RST, I0–I7VILV+ < 1.8V0.2 x V+VV+ ≥ 1.80.3 x V+
Input Leakage Current
SDA, SCL, AD0, AD2, RST, I0–I7IIH, IILSDA, SCL, AD0, AD2, RST, I0–I7 at V+ or
GND-0.2+0.2µA
Input Capacitance
SDA, SCL, AD0, AD2, RST, I0–I710pF
Output Low Voltage
O8–O15VOL
V+ = +1.71V, ISINK = 5mA (QSOP)90180
V+ = +1.71V, ISINK = 5mA (TQFN)90230
V+ = +2.5V, ISINK = 10mA (QSOP)110210
V+ = +2.5V, ISINK = 10mA (TQFN)110260
V+ = +3.3V, ISINK = 15mA (QSOP)130230
V+ = +3.3V, ISINK = 15mA (TQFN)130280
V+ = +5V, ISINK = 20mA (QSOP)140250
V+ = +5V, ISINK = 20mA (TQFN)140300
Output High Voltage
O8–O15VOH
V+ = +1.71V, ISOURCE = 2mAV+ - 250V+ - 30
V+ = +2.5V, ISOURCE = 5mAV+ - 360V+ - 70
V+ = +3.3V, ISOURCE = 5mAV+ - 260V+ - 100
V+ = +5V, ISOURCE = 10mAV+ - 360V+ - 120
Output Low-Voltage SDAVOLSDAISINK = 6mA250mV
Output Low-Voltage INTVOLINTISINK = 5mA130250mV
MAX7324I2C Port Expander with
Eight Push-Pull Outputs and Eight Inputs
DC Electrical CharacteristicsStresses 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.
Absolute Maximum Ratings
Note 1: All parameters are tested at TA = +25°C. 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.
(V+ = +1.71V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, TA = +25°C.) (Note 1)
(V+ = +1.71V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, TA = +25°C.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSerial-Clock FrequencyfSCL400kHz
Bus Free Time Between a STOP
and a START Condition tBUF1.3µs
Hold Time (Repeated) START
ConditiontHD,STA0.6µs
Repeated START Condition
Setup TimetSU,STA0.6µs
STOP Condition Setup TimetSU,STO0.6µs
Data Hold TimetHD,DAT(Note 2)0.9µs
Data Setup TimetSU,DAT100ns
SCL Clock Low PeriodtLOW1.3µs
SCL Clock High PeriodtHIGH0.7µs
Rise Time of Both SDA and SCL
Signals, ReceivingtR(Notes 3, 4)20 +
0.1Cb300ns
Fall Time of Both SDA and SCL
Signals, ReceivingtF(Notes 3, 4)20 +
0.1Cb300ns
Fall Time of SDA TransmittingtF,TX(Notes 3, 4)20 +
0.1Cb250ns
Pulse Width of Spike SuppressedtSP(Note 5)50ns
Capacitive Load for Each Bus
LineCb(Note 3)400pF
RST Pulse WidthtW500ns
RST Rising to START Condition
Setup TimetRST1µs
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSPort-Output Data ValidtPPVCL ≤ 100pF4µs
Port-Input Setup TimetPSUCL ≤ 100pF0µs
Port-Input Hold TimetPHCL ≤ 100pF4µs
INT Input Data Valid TimetIVCL ≤ 100pF4µs
INT Reset Delay Time from STOPtIPCL ≤ 100pF4µs
INT Reset Delay Time from
AcknowledgetIRCL ≤ 100pF4µs
MAX7324I2C Port Expander with
Eight Push-Pull Outputs and Eight Inputs
Timing Characteristics
Port and Interrupt INT Timing Characteristics
(TA = +25°C, unless otherwise noted.)
PINNAMEFUNCTIONQSOPTQFN22INTActive-Low Interrupt Output. INT is an open-drain output.23RSTActive-Low Reset Input. Drive RST low to clear the 2-wire interface.
3, 2124, 18AD2, AD0Address 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).
4–111–8I0–I7Input Ports. I0 to I7 are CMOS-logic inputs.9GNDGround
13–2010–1708–015Output Ports. O8–O15 are push-pull outputs rated at 20mA.19SCLI2C-Compatible Serial Clock Input20SDAI2C-Compatible Serial Data I/O21V+Positive Supply Voltage. Bypass V+ to GND with a ceramic capacitor of at least 0.047µF.
OUTPUT-VOLTAGE HIGH
vs. TEMPERATURETEMPERATURE (°C)
OUTPUT-VOLTAGE HIGH (V)
MAX7324 toc04
V+ = +3.3V
ISOURCE = 5mA
V+ = +5.0V
ISOURCE = 10mA
V+ = +2.5V ISOURCE = 5mA
V+ = +1.71V ISOURCE = 2mA
OUTPUT-VOLTAGE LOW
vs. TEMPERATURETEMPERATURE (°C)
OUTPUT-VOLTAGE LOW (V)
MAX7324 toc03
V+ = +3.3V
ISINK = 15mA
V+ = +5.0V
ISINK = 20mA
V+ = +2.5V
ISINK = 10mA
V+ = +1.71V
ISINK = 5mA
SUPPLY CURRENT
vs. TEMPERATURETEMPERATURE (°C)
SUPPLY CURRENT (A)
MAX7324 toc02
V+ = +3.3V
V+ = +5.0V
V+ = +2.5V
V+ = +1.71V
fSCL = 400kHz
STANDBY CURRENT
vs. TEMPERATURE TEMPERATURE (°C)
STANDBY CURRENT (A)
MAX7324 toc01
V+ = +3.3V
V+ = +5.0V
V+ = +2.5V
V+ = +1.71V
fSCL = 0kHz
MAX7324I2C Port Expander with
Eight Push-Pull Outputs and Eight Inputs
Pin Description
Typical Operating Characteristics
Detailed Description
MAX7324–MAX7327 Family ComparisonThe MAX7324–MAX7327 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 OverviewThe 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 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 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–MAX7329 Family Comparison
PART
I2C
SLAVE
ADDRESS
INPUTS
INPUT
INTERRUPT
MASK
OPEN-
DRAIN
OUTPUTS
PUSH-
PULL
OUTPUTS
CONFIGURATION
16-PORT EXPANDERS
MAX7324101xxxx
And
110xxxxYes—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.
MAX7325Up to 8—Up to 88
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.
MAX7324I2C Port Expander with
Eight Push-Pull Outputs and Eight Inputs
Table 1. MAX7319–MAX7329 Family Comparison (continued)
PART
I2C
SLAVE
ADDRESS
INPUTS
INPUT
INTERRUPT
MASK
OPEN-
DRAIN
OUTPUTS
PUSH-
PULL
OUTPUTS
CONFIGURATION
MAX7326101xxxx
and
110xxxxYes—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.
MAX7327Up to 4—Up to 412
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
MAX7319110xxxx8Yes——
Input-only versions:
8 input ports with programmable latching transition
detection interrupt and selectable pullups.
MAX7320101xxxx———8
Output-only versions:
8 push-pull outputs with selectable power-up default
levels.
MAX7321110xxxxUp to 8—Up to 8—
I/O versions:
8 open-drain I/O ports with latching transition
detection interrupt and selectable pullups.
MAX7322110xxxx4Yes—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.
MAX7324I2C 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-UpOn 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).
Power-On ResetThe 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).
RST InputThe 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 ModeWhen 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 SelectionAddress 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
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, includ-
ing 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,
Table 1. MAX7319–MAX7329 Family Comparison (continued)
PART
I2C
SLAVE
ADDRESS
INPUTS
INPUT
INTERRUPT
MASK
OPEN-
DRAIN
OUTPUTS
PUSH-
PULL
OUTPUTS
CONFIGURATION
MAX7323110xxxxUp to 4—Up to 44
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
MAX73290100xxx
0111xxxUp 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.
MAX7324I2C Port Expander with
Eight Push-Pull Outputs and Eight Inputs
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 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 I2C transmission (to any device, not neces-
sarily the MAX7324) is put on the bus.
Port InputsPort 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 DetectionAll 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.
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–I7
PIN CONNECTIONDEVICE ADDRESS40kΩ INPUT PULLUP ENABLED
AD2AD0A6A5A4A3A2A1A0I7I6I5I4I3I2I1I0SCLGND1100000YYYY————
SCLV+1100001YYYYYYYY
SCLSCL1100010YYYYYYYY
SCLSDA1100011YYYYYYYY
SDAGND1100100YYYY————
SDAV+1100101YYYYYYYY
SDASCL1100110YYYYYYYY
SDASDA1100111YYYYYYYY
GNDGND1101000————————
GNDV+1101001————YYYYGNDSCL1101010————YYYY
GNDSDA1101011————YYYY
GND1101100YYYY————V+1101101YYYYYYYYSCL1101110YYYYYYYYSDA1101111YYYYYYYY
MAX7324I2C 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 MasksThe 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–O15
PIN CONNECTIONDEVICE ADDRESSOUTPUTS POWER-UP DEFAULT
AD2AD0A6A5A4A3A2A1A0O15O14O13O12O11O10O9O8SCLGND101000011110000
SCLV+101000111111111
SCLSCL101001011111111
SCLSDA101001111111111
SDAGND101010011110000
SDAV+101010111111111
SDASCL101011011111111
SDASDA101011111111111
GNDGND101100000000000
GNDV+101100100001111GNDSCL101101000001111
GNDSDA101101100001111
GND101110011110000V+101110111111111SCL101111011111111SDA101111111111111
MAX7324I2C Port Expander with
Eight Push-Pull Outputs and Eight Inputs
