MAX7311 Maxim, MAX7311 Datasheet - Page 11

• Manufacturer Part Number: MAX7311
• Description: The MAX7311 2-wire-interfaced expander provides 16-bit parallel input/output (I/O) port expansion for SMBus™ and I²C applications
• Manufacturer: Maxim

The output port registers (Table 3) set the outgoing
logic levels of the I/Os defined as outputs by the
respective configuration register. Reads from the out-
put port registers reflect the value that is in the flip-flop
controlling the output selection, not the actual I/O value.
The polarity inversion registers (Table 4) enable polarity
inversion of pins defined as inputs by the respective
port configuration registers. Set the bit in the polarity
inversion register to invert the corresponding port pin’s
polarity. Clear the bit in the polarity inversion register to
retain the corresponding port pin’s original polarity.
The configuration registers (Table 5) configure the
directions of the I/O pins. Set the bit in the respective
configuration register to enable the corresponding port
as an input. Clear the bit in the configuration register to
enable the corresponding port as an output.
Table 2. Registers 0x00, 0x01—Input Port Registers
Table 3. Registers 0x02, 0x03—Output Port Registers
Table 4. Registers 0x04, 0x05—Polarity Inversion Registers
Table 5. Registers 0x06, 0x07—Configuration Registers
Table 6. Register 0x08—Timeout Register
Power-up default
Power-up default
Power-up default
Power-up default
BIT
BIT
BIT
BIT
BIT
2-Wire-Interfaced 16-Bit I/O Port Expander
with Interrupt and Hot-Insertion Protection
______________________________________________________________________________________
7
0
I/O15
I/O15
I15
O15
I/O7
I/O7
I7
O7
0
1
1
6
0
Polarity Inversion Registers
5
0
Configuration Registers
Output Port Registers
I/O14
I/O14
4
0
I14
O14
I/O6
I/O6
I6
O6
0
1
1
3
0
2
0
I/O13
I/O13
I13
I/O5
O13
I/O5
I5
O5
1
0
1
1
0
0
1
I/O12
I/O12
I/O4
I12
O12
I/O4
I4
O4
0
1
1
Set register 0x08 LSB (bit 0) to enable the bus timeout
function (Table 6) or clear it to disable the bus timeout
function. Enabling the timeout feature resets the
MAX7311 serial bus interface when SCL stops either high
or low during a read or write. If either SCL or SDA is low
for more than 29ms after the start of a valid serial transfer,
the interface resets itself and sets up SDA as an input.
The MAX7311 then waits for another START condition.
The MAX7311 goes into standby when the I
idle. Standby supply current is typically 2.9µA.
The I/O ports I/O0–I/O15, interrupt output INT, and serial
interface SDA, SCL, AD0–2 remain high impedance with
up to 6V asserted on them when the MAX7311 is pow-
ered down (V+ = 0V). The MAX7311 can therefore be
used in hot-swap applications. Note that each I/O’s
100kΩ pullup effectively becomes a 100kΩ pulldown
when the MAX7311 is powered down.
The MAX7311 operates from a supply voltage of 2V to
5.5V. Bypass the power supply to GND with a 0.047µF
capacitor as close to the device as possible. For the
QFN version, connect the exposed pad to GND.
I/O11
I/O11
O11
I/O3
I/O3
I11
O3
I3
0
1
1
Applications Information
Power-Supply Consideration
I/O10
I/O10
I/O2
I/O2
O10
I10
O2
I2
0
1
1
I/O1
I/O9
I/O1
I/O9
O1
O9
I1
I9
1
0
1
Hot Insertion
Bus Timeout
Standby
2
C bus is
I/O0
I/O8
I/O0
I/O8
O0
O8
I0
I8
0
1
1
11