MAXIM MAX7321 Technical data

General Description

The MAX7321 2-wire serial-interfaced peripheral fea­tures eight open-drain I/O ports with selectable internal
pullups and transition detection. Any port may be used
as a logic input or an open-drain output. Ports are over­voltage protected to +6V independent of supply voltage.

All I/O ports configured as inputs are continuously
monitored for state changes (transition detection).
State changes are indicated by the open-drain INT
output. The interrupt is latched, allowing detection of
transient changes. When the MAX7321 is subsequent­ly accessed through the serial interface, any pending
interrupt is cleared.

The open-drain 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 MAX7321.

The MAX7321 uses two address inputs with four-level
logic to allow 16 I

2

C slave addresses. The slave
address also determines the power-up logic state for
the I/O ports, and enables or disables internal 40kΩ
pullups in groups of four ports.

The MAX7321 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 MAX7321 is available in 16-pin QSOP and TQFN
packages, and is specified over the automotive temper­ature range (-40°C to +125°C).

Features

♦ 400kHz I2C Serial Interface

♦ +1.71V to +5.5V Operating Voltage

♦ 8 Open-Drain I/O Ports Rated to 20mA Sink Current

♦ I/O Ports Are Overvoltage Protected to +6V

♦ Any Port Can Be a Logic Input or an Open-Drain

Output

♦ Selectable I/O Port Power-Up Default Logic States

♦ Transient Changes Are Latched, Allowing Detection

Between Read Operations

♦ INT Output Alerts Change on Inputs

♦ AD0 and AD2 Inputs Select from 16 Slave

Addresses

♦ Low 0.6µA (typ) Standby Current

♦ -40°C to +125°C Operating Temperature

MAX7321

I2C Port Expander with 8 Open-Drain I/Os

________________________________________________________________ Maxim Integrated Products 1

19-3738; Rev 1; 4/06

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.

Ordering Information

PART

TEMP

PIN­PACKAGE

TOP

PKG

CODE

MAX7321AEE+

-40°C to
16 QSOP —

E16-4

MAX7321ATE+

-40°C to

T1633-4

Pin Configurations are continued at end of data sheet.
Typical Application Circuit and Functional Diagram appear
at end of data sheet.

Selector Guide

PART

INPUTS

INTERRUPT

MASK

OPEN­DRAIN

PUSH-PULL

OUTPUTS

MAX7319

8 Yes — —

MAX7320

—— — 8

MAX7321

—

—

MAX7322

4 Yes — 4

MAX7323

—

4

MAX7328

—

—

MAX7329

—

—

**EP = Exposed paddle.
+Denotes lead-free package.

Cell Phones

SAN/NAS

Servers

Notebooks

Satellite Radio

Automotive

Applications

Pin Configurations

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

AD0

V+

SDA

SCL

INT

P7

P6

P5

P4

MAX7321

QSOP

RST

AD2

P2

P0

P1

P3

GND

+

+

RANGE

+125°C

+125°C

16 TQFN-EP** ADC

MARK

OUTPUTS

Up to 8

Up to 4

Up to 8

Up to 8

Up to 8

Up to 4

Up to 8

Up to 8

MAX7321

I2C Port Expander with 8 Open-Drain I/Os

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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.

(All voltages referenced to GND.)

Supply Voltage V+....................................................-0.3V to +6V

SCL, SDA, AD0, AD2, RST, INT, P0–P7 ...................-0.3V to +6V

P0–P7 Sink Current ............................................................ 25mA

SDA Sink Current ............................................................... 10mA

INT Sink Current..................................................................10mA

Total V+ Current..................................................................50mA

Total GND Current ...........................................................100mA

Continuous Power Dissipation (T

A

= +70°C)

16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW

16-Pin TQFN (derate 15.6mW/°C above +70°C) .......1250mW

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

ELECTRICAL CHARACTERISTICS

(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)

Operating Supply Voltage V+ 1.71 5.50 V

Power-On Reset Voltage V

Standby Current
(Interface Idle)

Supply Current
(Interface Running)

Input High Voltage
SDA, SCL, AD0, AD2, RST, P0–P7

Input Low Voltage
SDA, SCL, AD0, AD2, RST, P0–P7

Input Leakage Current
SDA, SCL, AD0, AD2, RST, P0–P7

Input Capacitance
SDA, SCL, AD0, AD2, RST, P0–P7

Output Low Voltage
P0–P7

Output Low Voltage
SDA

Output Low Voltage

INT

Port Input Pullup Resistor R

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POR

I

STB

I

V

V

I

IH

V

V

OLSDAISINK

V

OLINTISINK

V+ falling 1.6 V

SCL and SDA and other digital inputs at V+ 0.6 1.5 µA

f

+

IH

, I

OL

PU

IL

IL

= 400kHz; other digital inputs at V+ 23 55 µA

SCL

V+ < 1.8V 0.8 x V+

V+ ≥ 1.8 0.7 x V+

V+ < 1.8V 0.2 x V+

V+ ≥ 1.8V 0.3 x V+
SDA, SCL, AD0, AD2, RST, P0–P7 at V+ or

GND, internal pullup disabled

V+ = +1.71V, I

V+ = +2.5V, I

V+ = +3.3V, I

V+ = +5V, I

= 6mA 250 mV

= 5mA 130 250 mV

= 5mA 90 180

SINK

= 10mA 110 210

SINK

= 15mA 130 230

SINK

= 20mA 140 250

SINK

-0.2 +0.2 µA

10 pF

25 40 55 kΩ

V

V

mV

MAX7321

I2C Port Expander with 8 Open-Drain I/Os

_______________________________________________________________________________________ 3

PORT AND INTERRUPT INT TIMING CHARACTERISTICS

(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)

TIMING CHARACTERISTICS

(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)

Note 1: All parameters 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 V

IL

of the SCL signal) in order 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. I

SINK

≤ 6mA. tRand tFmeasured 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.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Port Output Data Valid t

Port Input Setup Time t

Port Input Hold Time t

INT Input Data Valid Time t
INT Reset Delay Time from STOP t

INT Reset Delay Time from

Acknowledge

PPV

PSU

PH

t

CL ≤ 100pF 4 µs

CL ≤ 100pF 0 µs

CL ≤ 100pF 4 µs

CL ≤ 100pF 4 µs

IV

CL ≤ 100pF 4 µs

IP

CL ≤ 100pF 4 µs

IR

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Serial-Clock Frequency f

Bus Free Time Between a STOP
and a START Condition

Hold Time (Repeated) START
Condition

Repeated START Condition
Setup Time

t

t

STOP Condition Setup Time t

Data Hold Time t

Data Setup Time t

SCL Clock Low Period t

SCL Clock High Period t

Rise Time of Both SDA and SCL
Signals, Receiving

Fall Time of Both SDA and SCL
Signals, Receiving

Fall Time of SDA, Transmitting t

SCL

t

BUF

HD, STA

SU, STA

SU, STO

HD, DAT

SU, DAT

LOW

HIGH

t

R

t

F

F,TX

1.3 µs

0.6 µs

0.6 µs

0.6 µs

(Note 2) 0.9 µs

100 ns

1.3 µs

0.7 µs

(Notes 3, 4)

(Notes 3, 4)

(Notes 3, 4)

20 +

0.1C

20 +

0.1C

20 +

0.1C

400 kHz

300 ns

b

300 ns

b

250 ns

b

Pulse Width of Spike Suppressed t

Capacitive Load for Each Bus
Line

RST Pulse Width t

RST Rising to START Condition

Setup Time

C

t

RST

SP

W

(Note 5) 50 ns

(Note 3) 400 pF

b

500 ns

1µs

MAX7321

I2C Port Expander with 8 Open-Drain I/Os

4 _______________________________________________________________________________________

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

0

0.4

0.2

1.0

0.8

0.6

1.2

1.4

1.8

1.6

2.0

-40 -10 5-25 203550658095110125

STANDBY CURRENT vs. TEMPERATURE

MAX7321 toc01

TEMPERATURE (°C)

STANDBY CURRENT (μA)

V+ = +3.3V

V+ = +2.5V

V+ = +5.0V

V+ = +1.71V

f

SCL

= 0kHz

0

20

10

40

30

50

60

-40 -10 5 20-25 3550658095110125

SUPPLY CURRENT vs. TEMPERATURE

MAX7321 toc02

TEMPERATURE (°C)

SUPPLY CURRENT (μA)

V+ = +3.3V

V+ = +5.0V

V+ = +1.71V

V+ = +2.5V

f

SCL

= 400kHz

OUTPUT VOLTAGE LOW

vs. TEMPERATURE

TEMPERATURE (°C)

OUTPUT VOLTAGE LOW (V)

MAX7321 toc03

-40 -25 -10 5 20 35 50 65 80 95 110 125

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

V+ = +5.0V
I

SINK

= 20mA

V+ = +2.5V
I

SINK

= 10mA

V+ = +1.71V
I

SINK

= 5mA

V+ = +3.3V
I

SINK

= 15mA

Pin Description

PIN

QSOP TQFN

1, 3 15, 1

216RST Reset Input, Active Low. Drive RST low to clear the 2-wire interface.

4–7, 9–12 2–5, 7–10 P0–P7 Input/Output Ports. P0 to P7 are open-drain I/Os.

8 6 GND Ground

13 11 INT Interrupt Output. INT is an open-drain output.

14 12 SCL I2C-Compatible Serial Clock Input

15 13 SDA I2C-Compatible Serial Data I/O

16 14 V+

— EP EP Exposed Pad. Connect exposed pad to GND.

NAME FUNCTION

AD0,

AD2

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 Table 3).

Positive Supply Voltage. Bypass V+ to GND with a ceramic capacitor of at least

0.047µF as close to the device as possible.

Detailed Description

MAX7319–MAX7329 Family Comparison

The MAX7319–MAX7323 family consists of five pin­compatible, eight-port expanders. Each version is opti­mized for different applications. The MAX7328 and
MAX7329 are industry standard parts.

The MAX7324–MAX7327 family consists of four pin­compatible, 16-port expanders that integrate the func­tions of the MAX7320 and one of either the MAX7319,
MAX7321, MAX7322, or MAX7323.

Functional Overview

The MAX7321 is a general-purpose port expander
operating from a +1.71V to +5.5V supply that provides
eight open-drain I/O ports. Each open-drain output is
rated to sink 20mA, and the entire device is rated to
sink 100mA into all ports combined. The outputs drive
loads connected to supplies up to +5.5V, independent
of the MAX7321’s supply voltage.

The MAX7321 is set to one of 16 I

2

C slave addresses
(0x60 to 0x6F) using the address select inputs AD0 and
AD2, and is accessed over an I

2

C serial interface up to

400kHz. The RST input clears the serial interface in

MAX7321

I2C Port Expander with 8 Open-Drain I/Os

_______________________________________________________________________________________ 5

Table 1. MAX7319–MAX7329 Family Comparison

2

C

I

PART

8-PORT EXPANDERS

MAX7319 110xxxx 8 Yes — —

MAX7320 101xxxx — — — 8

SLAVE

ADDRESS

INPUTS

INPUT

INTERRUPT

MASK

OPEN­DRAIN

OUTPUTS

PUSH-

PULL

OUTPUTS

APPLICATION

Input-only versions:
8 input ports with programmable latching transition
detection interrupt and selectable pullups.

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
momentarily) since the ports were last read.
Output-only versions:
8 push-pull outputs with selectable power-up default
levels.

Push-pull outputs offer faster rise time than open­drain outputs, and require no pullup resistors.
I/O versions:
8 open-drain I/O ports with latching transition
detection interrupt and selectable pullups.

MAX7321 110xxxx Up to 8 — Up to 8 —

MAX7322 110xxxx 4 Yes — 4

Open-drain outputs can level shift the logic-high
state to a higher or lower voltage than V+ using
external pullup resistors. Any port can be used as an
input by setting the open-drain output to logic-high.
Transition flags identify which inputs have changed
(even momentarily) since the ports were last read.
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.

MAX7321

case of a bus lockup, terminating any serial transaction
to or from the MAX7321.

Any port can be configured as a logic input by setting
the port output logic-high (logic-high for an open-drain
output is high impedance). When the MAX7321 is read
through the serial interface, the actual logic levels at
the ports are read back.

The open-drain ports offer latching transition detection
when used as inputs. All input ports are continuously
monitored for changes. An input change sets 1 of 8 flag
bits that identify changed input(s). All flags are cleared
upon a subsequent read or write transaction to the
MAX7321.

A latching interrupt output, INT, is programmed to flag
logic changes on ports used as inputs. Data changes
on any input port forces INT to a logic-low. Changing
the I/O port level through the serial interface does not
cause an interrupt. The interrupt output INT is deassert­ed when the MAX7321 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 3).

Use the slave address selection to ensure that I/O ports
used as inputs are logic-high on power-up. I/O ports with

internal pullups enabled default to a logic-high output
state. Ports with internal pullups disabled default to a
logic-low output state. Output port power-up logic
states are selected by the address select inputs AD0
and AD2. Ports default to logic-high or logic-low on
power-up in groups of four (see Table 3).

Initial Power-Up

On power-up, the transition detection logic is reset, and
INT is deasserted. The transition flags are cleared to
indicate no data changes. The power-up default states
of the eight I/O ports are set according to the I2C slave
address selection inputs, AD0 and AD2 (Table 3). For

I/O ports used as inputs, ensure that the default
states are logic-high so that the I/O ports power up
in the high-impedance state. All I/O ports configured
with pullups enabled also have a logic-high power­up state.

Power-On Reset

The MAX7321 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 to
less than V

POR

, the MAX7321 resets all register con-

tents to the POR defaults (Table 3).

I2C Port Expander with 8 Open-Drain I/Os

6 _______________________________________________________________________________________

Table 1. MAX7319–MAX7329 Family Comparison (continued)

2

C

I

PART

MAX7323 110xxxx Up to 4 — Up to 4 4

SLAVE

ADDRESS

INPUTS

MAX7328
MAX7329

16-PORT EXPANDERS

MAX7324 8 Yes — 8 Software equivalent to a MAX7320 plus a MAX7319.

MAX7325 Up to 8 — Up to 8 8 Software equivalent to a MAX7320 plus a MAX7321.

MAX7326 4 Yes — 12 Software equivalent to a MAX7320 plus a MAX7322.

MAX7327

0100xxx
0111xxx

101xxxx

and

110xxxx

Up to 8 — Up to 8 —

Up to 4 — Up to 4 12 Software equivalent to a MAX7320 plus a MAX7323.

INPUT

INTERRUPT

MASK

OPEN­DRAIN

OUTPUTS

PUSH-

PULL

OUTPUTS

APPLICATION

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.
8 open-drain I/O ports with nonlatching transition
detection interrupt and pullups on all ports.

All ports power up as inputs (or logic-high outputs).

Any port can be used as an input by setting the
open-drain output to logic-high.