MAX7312 Maxim, MAX7312 Datasheet - Page 6

• Manufacturer Part Number: MAX7312
• Description: The MAX7312 2-wire-interfaced expander provides 16-bit parallel input/output (I/O) port expansion in SMBus™ and I²C applications
• Manufacturer: Maxim

The MAX7312 general-purpose input/output (GPIO)
peripheral provides up to 16 I/O ports, controlled
through an I
MAX7312 consists of input port registers, output port
registers, polarity inversion registers, configuration reg-
isters, and a bus-timeout register. Upon power-on, all
I/O lines are set as inputs. Three slave ID address select
pins, AD0, AD1, and AD2, choose one of 64 slave ID
addresses, including the eight addresses supported by
the Phillips PCA9555. Table 1 is the register address
table. Tables 2–6 show detailed register information.
2-Wire-Interfaced 16-Bit I/O Port Expander
with Interrupt and Hot-Insertion Protection
Figure 1. MAX7312 Block Diagram
Figure 2. 2-Wire Serial Interface Timing Diagram
6
_______________________________________________________________________________________
SDA
SCL
t
HD, STA
START CONDITION
2
C-compatible serial interface. The
Detailed Description
t
LOW
AD0
AD1
AD2
SCL
SDA
V
+
t
R
N
t
HIGH
t
SU, DAT
t
F
POWER-ON
FILTER
INPUT
RESET
t
HD, DAT
CONTROL
SMBus
MAX7312
t
SU, STA
REPEATED START CONDITION
GND
WRITE PULSE
WRITE PULSE
The MAX7312 operates as a slave that sends and
receives data through a 2-wire 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). A master, typically a microcon-
troller, initiates all data transfers to and from the
MAX7312, and generates the SCL clock that synchro-
nizes the data transfer (Figure 2).
READ PULSE
READ PULSE
8 BIT
8 BIT
t
HD, STA
INPUT/OUTPUT
INPUT/OUTPUT
PORT 1
PORT 2
t
SU, STO
STOP CONDITION
I/O0
I/O1
I/O2
I/O3
I/O4
I/O5
I/O6
I/O7
I/O8
I/O9
I/O10
I/O11
I/O12
I/O13
I/O14
I/O15
INT
Serial Interface
Serial Addressing
t
BUF
START CONDITION