MAX7310 Maxim, MAX7310 Datasheet - Page 8

• Manufacturer Part Number: MAX7310
• Description: The MAX7310 provides 8-bit parallel input/output port expansion for SMBus™-compatible and I²C-compatible applications
• Manufacturer: Maxim

The output port register sets the outgoing logic levels of
the I/O ports, defined as outputs by the configuration
register. Reads from the output port register reflect the
value that is in the flip-flop controlling the output selec-
tion, not the actual I/O value, which may differ if the out-
put is overloaded.
2-Wire-Interfaced 8-Bit I/O Port Expander
with Reset
Table 1. Register Address
Table 2. Register 0—Input Port Register
Table 3. Register 1—Output Port Register
Table 4. Register 2—Polarity Inversion Register
Table 5. Register 3—Configuration Register
Table 6. Register 4—Timeout Register
8
BIT
REGISTER
ADDRESS
_______________________________________________________________________________________
(hex)
0x00
0x01
0x02
0x03
0x04
0xFF
Default
Default
Default
Default
BIT
BIT
BIT
BIT
I7
I6
Output port register
Input port register
Reserved register
Polarity inversion
Timeout register
Configuration
FUNCTION
I5
register
register
I/O7
I/O7
O7
T7
0
1
1
x
I4
I3
I/O6
I/O6
Read byte.
Read/write byte.
Read/write byte.
Read/write byte.
Read/write byte.
Factory reserved.
Do not write to this
register.
O6
T6
0
1
1
x
I2
PROTOCOL
I1
I/O5
I/O5
O5
T5
0
1
1
x
I0
I/O4
I/O4
O4
T4
The polarity inversion register enables polarity inversion
of ports defined as inputs by the configuration register.
Set the bit in the polarity inversion register (write with a
1) to invert the corresponding port pin’s polarity. Clear
the bit in the polarity inversion register (write with a
zero) to retain the corresponding port pin’s original
polarity.
The configuration register configures the directions of
the ports. Set the bit in the configuration register to
enable the corresponding port pin as an input with a
high-impedance output driver. Clear the bit in the con-
figuration register to enable the corresponding port pin
as an output.
Set bit T0 to enable the bus timeout function and low to
disable the bus timeout function. Enabling the timeout
feature resets the serial bus interface when SCL stops
either high or low during a read or write access to the
MAX7310. If either SCL or SDA is low for more than
30ms min and 60ms max after the start of a valid serial
transfer, the interface resets itself. Resetting the serial
bus interface sets up SDA as an input. The MAX7310
then waits for another start condition.
The MAX7310 goes into standby when all pins are set
to V+ or GND. Standby supply current is typically
1.7µA.
1
1
0
x
I/O3
I/O3
O3
T3
0
1
0
x
I/O2
I/O2
O2
T2
0
0
1
x
I/O1
I/O1
O1
T1
0
0
1
x
Standby
I/O0
I/O0
O0
T0
0
0
1
1