19-3738; Rev 0; 7/05
I
2
C Port Expander with 8 Open-Drain I/Os
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 pro-
tected to +6V independent of supply voltage.
All I/O ports configured as inputs are continuously mon-
itored for state changes (transition detection). State
changes are indicated by the open-drain, +6V tolerant
INT
output. The interrupt is latched, allowing detection
of transient changes. When the MAX7321 is subse-
quently 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 +6V tolerant
RST
input clears the serial interface,
terminating any I
2
C* 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 level for
the I/O ports, and enables or disables internal 40kΩ
pullups in groups of four ports.
The MAX7321 supports hot insertion. All eight I/O ports,
the serial interface SDA, SCL, AD0, AD2,
INT,
and
RST
remain high impedance in power-down (V+ = 0) with
up to +6V asserted on them.
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 16-pin
TQFN packages, and is specified over the automotive
temperature range (-40°C to +125°C).
♦
+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 Levels
♦
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), 1.5µA (max) Standby Current
♦
-40°C to +125°C Operating Temperature
Features
♦
400kHz, +6V Tolerant I
2
C Serial Interface
MAX7321
Ordering Information
PART
MAX7321AEE
TEMP
RANGE
-40°C to
+125°C
-40°C to
+125°C
-40°C to
+125°C
-40°C to
+125°C
-40°C to
+125°C
PIN-
PACKAGE
16 QSOP
16 TQFN
3mm x 3mm
x 0.8mm
16 SO
20 TSSOP
20 SSOP
TOP
MARK
—
PKG
CODE
E16-4
MAX7321ATE
ADC
T1633-4
MAX7321ASE*
MAX7321AUP*
—
—
—
—
—
—
Applications
Cell Phones
SAN/NAS
Servers
Notebooks
Satellite Radio
Automotive
MAX7321AAP*
*Future product—contact factory for availability.
Selector Guide
PART
MAX7319
INPUTS
8
—
Up to 8
4
Up to 4
Up to 8
Up to 8
INTERRUPT
MASK
Yes
—
—
Yes
—
—
—
OPEN-
PUSH-PULL
DRAIN
OUTPUTS
OUTPUTS
—
—
Up to 8
—
Up to 4
Up to 8
Up to 8
—
8
—
4
4
—
—
Pin Configurations, Typical Application Circuit, and
Functional Diagram appear at end of data sheet.
*Purchase of I
2
C components from Maxim Integrated Products,
Inc., or one of its sublicensed Associated Companies, conveys
a license under the Philips I
2
C Patent Rights to use these com-
ponents in an I
2
C system, provided that the system conforms
to the I
2
C Standard Specification as defined by Philips.
MAX7320
MAX7321
MAX7322
MAX7323
MAX7328
MAX7329
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
I
2
C Port Expander with 8 Open-Drain I/Os
MAX7321
ABSOLUTE MAXIMUM RATINGS
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
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.
ELECTRICAL CHARACTERISTICS
(V+ = +1.71V to +5.5V, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, T
A
= +25°C.) (Note 1)
PARAMETER
Operating Supply Voltage
Power-On Reset Voltage
Standby Current
(Interface Idle)
Supply Current
(Interface Running)
Input High Voltage
SDA, SCL, AD0, AD2,
RST,
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
V+ = +1.71V, I
SINK
= 5mA
Output Low Voltage
P0–P7
V
OL
V+ = +2.5V, I
SINK
= 10mA
V+ = +3.3V, I
SINK
= 15mA
V+ = +5V, I
SINK
= 20mA
Output Low Voltage
SDA
Output Low Voltage
INT
Port Input Pullup Resistor
V
OLSDA
V
OLINT
R
PU
I
SINK
= 6mA
I
SINK
= 5mA
25
130
40
SYMBOL
V+
V
POR
I
STB
I
+
V
IH
V
IL
I
IH
, I
IL
SCL and SDA and other digital inputs at V+
f
SCL
= 400kHz; other digital inputs at V+
V+
≤
1.8V
V+
≥
1.8
V+
≤
1.8V
1.71V
≤
V+
≤
1.8V
SDA, SCL, AD0, AD2,
RST,
P0–P7 at V+ or
GND
-0.2
10
90
110
130
140
180
210
230
250
250
250
55
mV
mV
kΩ
mV
0.8 x V+
0.7 x V+
0.2 x V+
0.3 x V+
+0.2
0.6
23
CONDITIONS
MIN
1.71
TYP
MAX
5.5
1.6
1.5
51
UNITS
V
V
µA
µA
V
V
µA
pF
2
_______________________________________________________________________________________
I
2
C Port Expander with 8 Open-Drain I/Os
PORT AND INTERRUPT
INT
TIMING CHARACTERISTICS
(V+ = +1.71V to +5.5V, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, T
A
= +25°C.) (Note 1)
PARAMETER
Port Output Data Valid
Port Input Setup Time
Port Input Hold Time
INT
Input Data Valid Time
INT
Reset Delay Time from STOP
INT
Reset Delay Time from
Acknowledge
SYMBOL
t
PPV
t
PSU
t
PH
t
IV
t
IP
t
IR
C
L
≤
100pF
C
L
≤
100pF
C
L
≤
100pF
C
L
≤
100pF
C
L
≤
100pF
C
L
≤
100pF
0
4
4
4
4
CONDITIONS
MIN
TYP
MAX
4
UNITS
µs
µs
µs
µs
µs
µs
MAX7321
TIMING CHARACTERISTICS
(V+ = +1.71V to +5.5V, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, T
A
= +25°C.) (Note 1)
PARAMETER
Serial Clock Frequency
Bus Free Time Between a STOP
and a START Condition
Hold Time (Repeated) START
Condition
Repeated START Condition
Setup Time
STOP Condition Setup Time
Data Hold Time
Data Setup Time
SCL Clock Low Period
SCL Clock High Period
Rise Time of Both SDA and SCL
Signals, Receiving
Fall Time of Both SDA and SCL
Signals, Receiving
Fall Time of SDA, Transmitting
Pulse Width of Spike Suppressed
Capacitive Load for Each Bus
Line
RST
Pulse Width
RST
Rising to START Condition
Setup Time
SYMBOL
f
SCL
t
BUF
t
HD, STA
t
SU, STA
t
SU, STO
t
HD, DAT
t
SU, DAT
t
LOW
t
HIGH
t
R
t
F
t
F,TX
t
SP
C
b
t
W
t
RST
(Notes 3, 4)
(Notes 3, 4)
(Notes 3, 4)
(Note 5)
(Note 3)
500
1
(Note 2)
100
1.3
0.7
20 +
0.1C
b
20 +
0.1C
b
20 +
0.1C
b
50
400
300
300
250
1.3
0.6
0.6
0.6
0.9
CONDITIONS
MIN
TYP
MAX
400
UNITS
kHz
µs
µs
µs
µs
µs
ns
µs
µs
ns
ns
ns
ns
pF
ns
µs
Note 1:
All parameters tested at T
A
= +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. 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.
_______________________________________________________________________________________
3
I
2
C Port Expander with 8 Open-Drain I/Os
MAX7321
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
OUTPUT VOLTAGE LOW
vs. TEMPERATURE
MAX7321 toc02
STANDBY CURRENT vs. TEMPERATURE
1.8
STANDBY CURRENT (µA)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
0
V+ = +1.71V
V+ = +2.5V
V+ = +3.3V
V+ = +5.0V
f
SCL
= 0kHz
MAX7321 toc01
SUPPLY CURRENT vs. TEMPERATURE
60
f
SCL
= 400kHz
50
SUPPLY CURRENT (µA)
40
30
20
10
V+ = +1.71V
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
V+ = +3.3V
V+ = +5.0V
0.40
0.35
OUTPUT VOLTAGE LOW (V)
0.30
0.25
0.20
0.15
0.10
0.05
0
V+ = +5.0V
I
SINK
= 20mA
V+ = +3.3V
I
SINK
= 15mA
V+ = +2.5V
I
SINK
= 10mA
V+ = +2.5V
V+ = +1.71V
I
SINK
= 5mA
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
Pin Description
PIN
QSOP
1, 3
2
TQFN
15, 1
16
TSSOP/
SSOP
6, 9
7
10, 11,
12, 14,
16, 17,
19, 20
15
1
2
4
5
3,18
—
NAME
FUNCTION
AD0,
AD2
RST
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).
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 rated at +6V, 20mA.
8
13
14
15
16
—
—
6
11
12
13
14
—
EP
GND
INT
SCL
SDA
V+
N.C.
EP
Ground
Interrupt Output.
INT
is an open-drain output rated at +6V.
I
2
C-Compatible Serial Clock Input
I
2
C-Compatible Serial Data I/O
Positive Supply Voltage. Bypass V+ to GND with a ceramic capacitor of at
No Connection. Internally not connected.
Exposed Pad. Connect exposed pad to GND.
4
_______________________________________________________________________________________
MAX7321 toc03
2.0
I
2
C Port Expander with 8 Open-Drain I/Os
Detailed Description
MAX7319–MAX7329 Family Comparison
The MAX7319–MAX7323 family consists of five pin-
compatible, eight-port expanders. Each version is opti-
mized for different applications. The MAX7328 and
MAX7329 are second sources to the PCF8574 and
PCF8574A.
The MAX7324–MAX7327 family consists of four pin-
compatible, 16-port expanders that integrate the func-
tions 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 +6V, 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
Table 1. MAX7321–MAX7329 Family Comparison
PART
I
2
C
SLAVE
INPUTS
ADDRESS
INPUT
INTERRUPT
MASK
OPEN-
DRAIN
OUTPUTS
PUSH-
PULL
OUTPUTS
APPLICATION
8-PORT EXPANDERS
Input-only versions:
8 input ports with programmable latching transition
detection interrupt and selectable pullups.
MAX7319
110xxxx
8
Yes
—
—
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 open-
drain 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
—
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.
MAX7320
101xxxx
—
—
—
8
MAX7322
110xxxx
4
Yes
—
4
_______________________________________________________________________________________
5
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