MAX7326ATG+ ,I²C Port Expander with 12 Push-Pull Outputs and Four Inputsfeatures ● 400kHz I C Serial Interface16 I/O ports. The ports are divided into 12 push-pull out-● + ..
MAX7327AATG+ ,I²C Port Expander with 12 Push-Pull Outputs and 4 Open-Drain I/OsApplications● Cell Phones ● NotebooksSelector Guide● SAN/NAS ● Satellite RadioOPEN-● Servers INTERR ..
MAX7327AATG+T ,I²C Port Expander with 12 Push-Pull Outputs and 4 Open-Drain I/Osfeatures 12 push-pull outputs and four configurable open-● +1.71V to +5.5V Operating Voltagedrain I ..
MAX7328AAP+ ,I²C Port Expanders with Eight I/O PortsApplications● RAIDMAX7328AWE -40°C to +125°C 16 Wide SO● ServersMAX7328AAP -40°C to +125°C 20 SSOP● ..
MAX7328AWE+ ,I²C Port Expanders with Eight I/O PortsFeatures2● 100kHz, 5.5V-Tolerant, I C-Compatible Serial The MAX7328/MAX7329 are 2-wire serial-inter ..
MAX732CPA ,+5V/Adjustable Step-Up Current-Mode DC-DC ConvertersELECTRICAL CHARACTERISTICS
(Circuit of Figure 2, V+ = 5V, ILOAD = 0mA, TA = TMIN to TMAX, unless ..
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
MAX7326ATG+
I²C Port Expander with 12 Push-Pull Outputs and Four 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 MAX7326 2-wire serial-interfaced peripheral features
16 I/O ports. The ports are divided into 12 push-pull out-
puts and four input ports with selectable internal pullups.
Input ports are overvoltage protected to +6V and feature
transition detection with interrupt output.
The four input ports are continuously monitored for state
changes (transition detection). The interrupt is latched,
allowing detection of transient changes. Any combina-
tion of inputs can be selected using the interrupt mask
to assert the open-drain, +6V-tolerant INT output. When
the MAX7326 is subsequently accessed through the
serial interface, any pending interrupt is cleared. The 12
push-pull outputs are rated to sink 20mA and are capable
of driving LEDs. The RST input clears the serial inter-
ace, terminating any I2C communication to or from the
MAX7326.
The MAX7326 uses two address inputs with four-level
logic to allow 16 I2C slave addresses. The slave address
also sets the power-up default state for the 12 output
ports and enables or disables internal 40kΩ pullups in
groups of two input ports.
The MAX7326 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 MAX7326 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 I2C Serial Interface●+1.71V to +5.5V Operating Voltage ●12 Push-Pull Outputs Rated at 20mA Sink Current●4 Input Ports with Matchable 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-PACKAGEMAX7326AEG+-40°C to +125°C24 QSOP
MAX7326ATG+-40°C to +125°C24 TQFN-EP*
(4mm x 4mm)
TQFN (4mm x 4mm)TOP VIEW
MAX7326234561716151413
SCL
SDA
INT
AD2O1I2I3I4I5
AD0O15O13O12O11
RST
O10
GND
O14
EXPOSED PAD
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 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, I2–I5 ...................-0.3V to +6V
O0, O1, O6–O15 .......................................-0.3V to V+ + 0.3V
O0, O1, O6–O15 Output Current .................................25mA
SDA Sink Current .............................................................. 10mA
INT Sink Current.................................................................10mA
Total V+ Current .................................................................50mA
Total GND Current ...........................................................100mA
Continuous Power Dissipation (TA = +70°C)24-Pin QSOP (derate 9.5mW/°C over +70°C) .........761.9mW 24-Pin TQFN (derate 20.8mW/°C over +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, I2–I5VIHV+ < 1.8V0.8 x V+VV+ ≥ 1.8V0.7 x V+
Input Low-Voltage SDA, SCL, AD0,
AD2, RST, I2–I5VILV+ < 1.8V0.2 x V+VV+ ≥ 1.8V0.3 x V+
Input Leakage Current SDA, SCL,
AD0, AD2, RST, I2–I5IIH, IILSDA, SCL, AD0, AD2, RST, I2–I5 at V+ or
GND-0.2+0.2µA
Input Capacitance SDA, SCL, AD0,
AD2, RST, I2–I510pF
Output Low-Voltage O0, O1,
O6–O15VOL
V+ = +1.71V, ISINK = 5mA
QSOP90180
TQFN90230
V+ = +2.5V, ISINK = 10mAQSOP110210
TQFN110260
V+ = +3.3V, ISINK = 15mAQSOP130230
TQFN130280
V+ = +5V, ISINK = 20mAQSOP140250
TQFN140300
Output High-Voltage O0, O1,
O6–O15VOH
V+ = +1.71V, ISOURCE = 2mAV+ - 250V+ - 30V+ = +2.5V, ISOURCE = 5mAV+ - 360V+ - 30
V+ = +3.3V, ISOURCE = 5mAV+ - 260V+ - 30
V+ = +5V, ISOURCE = 10mAV+ - 360V+ - 30
Output Low-Voltage SDAVOLSDAISINK = 6mA250mV
Output Low-Voltage INTVOLINTISINK = 5mA130250mV
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 Inputs
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. ISINK ≤ 6mA. tR and tF measured between 0.3 x V+ and 0.7 x V+.
Note 5: Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns.
(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)
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
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSerial Clock FrequencyfSCL400kHz
Bus Free Time Between a STOP
and a START ConditiontBUF1.3µs
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
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 Inputs
Timing Characteristics
Port and Interrupt INT Timing Characteristics
(TA = +25°C, unless otherwise noted.)
PINNAMEFUNCTIONQSOPTQFN22INTInterrupt Output, Active Low. INT is an open-drain output.23RSTReset Input, Active Low. 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, 5, 10,
11, 13–20
1, 2, 7, 8,
O0, O1,
O6–O15Output Ports. These push-pull outputs are rated at 20mA.
6–93–6 I2–I5Input Ports. I2 and I5 are CMOS-logic inputs protected to +6V.9GNDGround19SCLI2C-Compatible Serial-Clock Input20SDAI2C-Compatible Serial-Data I/O21V+Positive Supply Voltage. Bypass V+ to GND with a 0.047µF ceramic capacitor.
OUTPUT-VOLTAGE HIGH
vs. TEMPERATURETEMPERATURE (°C)
OUTPUT-VOLTAGE HIGH (V)
MAX7326 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)
MAX7326 toc03
V+ = +3.3V
ISINK = 15mA
V+ = +5.0V
ISINK = 20mA
V+ = +2.5V
ISINK = 10mA
V+ = +1.71V
ISINK = 5mA
V+ = +1.62V
ISINK = 4mA
SUPPLY CURRENT
vs. TEMPERATURETEMPERATURE (°C)
SUPPLY CURRENT (A)
MAX7326 toc02
V+ = +3.3V
V+ = +5.0V
V+ = +2.5V
V+ = +1.71V
fSCL = 400kHz
STANDBY CURRENT
vs. TEMPERATURE TEMPERATURE (°C)
STANDBY CURRENT (A)
MAX7326 toc01
V+ = +3.3V
V+ = +5.0V
V+ = +2.5V
V+ = +1.71V
fSCL = 0kHz
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 Inputs
Pin Description
Typical Operating Characteristics
Detailed Description
MAX7319–MAX7329 Family ComparisonThe MAX7324–MAX7327 family consists of four pin-
compatible, 16-port expanders that integrate the
functions of the MAX7320 and one of either the MAX7319,
MAX7321, MAX7322, or MAX7323.
Functional OverviewThe MAX7326 is a general-purpose port expander
operating from a +1.71V to +5.5V supply that provides
12 push-pull output ports with 20mA sink, 10mA source
drive capability, and four CMOS input ports that are
overvoltage protected to +6V. The MAX7326 is rated to
sink a total of 100mA and source a total of 50mA from all
12 combined outputs.
The MAX7326 is set to two of 32 I2C slave addresses
(see Tables 2 and 3) using address inputs AD0 and AD2,
and is accessed over an I2C serial interface up to 400kHz.
Eight outputs use a different slave address from the other
four outputs and four inputs. Eight push-pull outputs (O8–
O15) use the 101xxxx addresses while the four outputs
(O0, O1, O6, and O7) and inputs (I2–I5) use addresses
with 110xxxx. The RST input clears the serial interface in
case of a bus lockup, terminating any serial transaction to
or from the MAX7326.
Table 1. MAX7319–MAX7329 Family Comparison
PART
I2C
SLAVE
ADDRESS
INPUTS
INPUT
INTERRUPT
MASK
OPEN-
DRAIN
OUTPUTS
PUSH-
PULL
OUTPUTS
CONFIGURATION
16-PORT EXPANDERSMAX7324
101xxxx
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.
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 Inputs
Table 1. MAX7319–MAX7329 Family Comparison (continued)
PART
I2C
SLAVE
ADDRESS
INPUTS
INPUT
INTERRUPT
MASK
OPEN-
DRAIN
OUTPUTS
PUSH-
PULL
OUTPUTS
CONFIGURATIONMAX7326
101xxxx
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 EXPANDERSMAX7319110xxxx8Yes——
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.
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 Inputs
When the MAX7326 is read through the serial interface,
the actual logic levels at the ports are read back.
The four input ports offer latching transition detection
functionality. All input ports are continuously monitored
for changes. An input change sets 1 of 4 flag bits that
identify the changed input(s). All flags are cleared upon a
subsequent read or write transaction to the MAX7326.
A latching interrupt output (INT) is programmed to flag
input data changes on the four input ports through an
interrupt mask register. By default, data changes on any
input port force INT to a logic-low. Interrupt output INT and
all transition flags are deasserted when the MAX7326 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 two (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
0x3C, enabling the interrupt output for transitions on
all four input ports. The transition flags are cleared to
indicate no data changes. The power-up default states
of the 12 push-pull outputs are set according to the I2C
slave address selection inputs, AD0 and AD2 (see Tables
2 and 3). Pullups are enabled on the input port in groups
of two (see Table 2).
Power-On Reset (POR)The MAX7326 contains an integral 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
MAX7326 resets all output register contents to the POR
defaults (Tables 2 and 3).
RST InputThe active-low RST input operates as a reset that voids
any I2C transaction involving the MAX7326 and forcing
the MAX7326 into the I2C STOP condition. The reset
action does not clear the interrupt output (INT).
Standby ModeWhen the serial interface is idle, the MAX7326 auto-
matically enters standby mode, drawing minimal supply
current.
Slave Address, Power-Up Default
Logic Levels, and Input Pullup SelectionAddress inputs AD0 and AD2 determine the MAX7326
slave address and select which inputs have pullup
resistors. Pullups are enabled on the input ports in
groups of two (see Table 2).
The MAX7326 slave address is determined on each I2C
transmission, regardless of whether the transmission
is actually addressing the MAX7326. The MAX7326
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
MAX7326 slave address can be configured dynamically in
the application without cycling the device supply.
On initial power-up, the MAX7326 cannot decode address
inputs AD0 and AD2 fully until the first I2C transmission.
This is important because the address selection is used to
determine the power-up logic state (output low or I/O high),
and whether pullups are enabled. However, at power-up,
the I2C SDA and SCL bus interface lines are high imped-
ance at the pins of every device (master or slave) connect-
ed to the bus, including the MAX7326. This is guaranteed
as part of the I2C specification. Therefore, when address
inputs AD0 and AD2 are connected to SDA or SCL during
power-up, they appear to be connected to V+. The port
Table 1. MAX7319–MAX7329 Family Comparison (continued)
PART
I2C
SLAVE
ADDRESS
INPUTS
INPUT
INTERRUPT
MASK
OPEN-
DRAIN
OUTPUTS
PUSH-
PULL
OUTPUTS
CONFIGURATIONMAX7323110xxxxUp 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
MAX7329
0100xxx
0111xxxUp to 8—Up to 8—8 open-drain I/O ports with nonlatching transition
detection interrupt and pullups on all ports.
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 Inputs
selection logic uses AD0 to select whether pullups are
enabled for ports I2 and I3, and to set the initial logic
level for those ports, and AD2 for ports I4 and I5. The
rule is that a logic-high, SDA, or SCL connection selects
the pullups and sets the default logic state to high. A
logic-low sets the default to low (Tables 2 and 3). This means
that the port configuration is correct on power-up for a
standard I2C configuration, where SDA or SCL are pulled
up to V+ by the external I2C pullup resistors.
The power-up default states of the 12 push-pull outputs
are set according to the I2C slave address selection
inputs, AD0 and AD2 (Tables 2 and 3).
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
MAX7326’s supply voltage, and if that pullup supply rises
later than the MAX7326’s supply, then SDA or SCL may
appear at power-up to be connected to GND. In appli-
cations like this, use the four address combinations that
are selected by strapping address inputs AD0 and AD2 to
V+ or ground (shown in bold in Tables 2 and 3). These
selections are guaranteed to be correct at power-up,
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 MAX7326) is put on the bus, and an unexpected
combination of ports may initialize as logic-low outputs
instead of inputs or logic-high outputs.
Port InputsPort inputs switch at CMOS-logic levels as determined by
the expander’s supply voltage, and are overvoltage toler-
ant to +6V, independent of the expander’s supply voltage.
Port-Input Transition DetectionAll four input ports are monitored for changes since the
expander was last accessed through the serial inter-
face. The state of the input ports is stored in an internal
“snapshot” register for transition monitoring. The snap-
shot 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
four port inputs are sampled (internally latched into the
snapshot register) and the old transition flags are cleared
during the I2C acknowledge of every MAX7326 read and
write access. The previous port transition flags are read
through the serial interface as the second byte of a 2-byte
Table 2. MAX7326 Address Map for Ports O0, O1, I2–I5, O6, and O7
PIN
CONNECTIONDEVICE ADDRESSPORT POWER-UP DEFAULT40kΩ INPUT PULLUPS ENABLED
AD2AD0A6A5A4A3A2A1A0O7O6I5I4I3I2O1O0O7O6I5I4I3I2O1O0SCLGND110000011
Inputs0
Pullups are not enabled for push-pull outputs.Y——
Pullups are not enabled for push-pull outputs.
SCLV+11000011111YYYY
SCLSCL11000101111YYYY
SCLSDA11000111111YYYY
SDAGND11001001100YY——
SDAV+11001011111YYYY
SDASCL11001101111YYYY
SDASDA11001111111YYYY
GNDGND11010000000————
GNDV+11010010011——YYGNDSCL11010100011——YY
GNDSDA11010110011——YY
GND11011001100YY——V+11011011111YYYYSCL11011101111YYYYSDA11011111111YYYY
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 Inputs
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 tran-
sition flags repeatedly reset for each pair of bytes read.
All changes that occur during a long read sequence are
detected and reported.
The MAX7326 includes a 4-bit interrupt mask register that
selects which inputs generate an interrupt upon change.
Each input’s transition flag is set when its input chang-
es, 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 change flag
and an interrupt mask bit for each of the four input ports.
The four change flags can be read through the serial
interface, and the 4-bit interrupt mask is set through the
serial interface.
Each port’s change 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 MAX7326 periodically to monitor less-important
inputs. The change flags indicate whether a permanent
or transient change has occurred on any input since the
MAX7326 was last accessed.
Table 3. MAX7326 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
GNDSDA101101100001111GND101110011110000
V+101110111111111SCL101111011111111SDA101111111111111
MAX7326I2C Port Expander with
12 Push-Pull Outputs and 4 Inputs
