MAX7323 Maxim, MAX7323 Datasheet - Page 6

• Manufacturer Part Number: MAX7323
• Description: The MAX7323 2-wire serial-interfaced peripheral features eight I/O ports
• Manufacturer: Maxim

I
and 4 Open-Drain I/Os
Any of the four open-drain ports 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 MAX7323 is read through the serial interface,
the actual logic levels at the ports are read back.
The four ports offer latching transition detection func-
tionality. All input ports are continuously monitored for
changes. An input change sets 1 of 4 flag bits that
identify changed input(s). All flags are cleared upon a
subsequent read or write transaction to the MAX7323.
A latching interrupt output, INT, automatically flags data
changes on any of the I/O ports used as inputs. The
interrupt output INT, and all transition flags are
deasserted when the MAX7323 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 two (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. I/O 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 two (see Table 3).
Table 1. MAX7319–MAX7329 Family Comparison (continued)
6
16-PORT EXPANDERS
MAX7323
MAX7328
MAX7329
MAX7324
MAX7325
MAX7326
MAX7327
2
PART
_______________________________________________________________________________________
C Port Expander with 4 Push-Pull Outputs
ADDRESS
0100xxx
0111xxx
110xxxx
101xxxx
110xxxx
SLAVE
and
I
2
C
INPUTS
Up to 4
Up to 8
Up to 8
Up to 4
8
4
INTERRUPT
INPUT
MASK
Yes
Yes
—
—
—
—
OUTPUTS
Up to 4
Up to 8
Up to 8
Up to 4
OPEN-
DRAIN
—
—
OUTPUTS
PUSH-
PULL
On power-up, the transition detection logic is reset, and
INT is deasserted. The interrupt mask register is set to
0x3C, enabling the interrupt output for transitions on all
four input ports. The transition flags are cleared to indi-
cate no data changes. The power-up default state of the
four push-pull outputs is set according to the I
address selection inputs, AD0 and AD2 (see Table 3).
The MAX7323 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
(1.6V max), the POR circuit releases the registers and
2-wire interface for normal operation. When V+ drops to
less than V
POR defaults (see Table 3).
The active-low RST input operates as a reset that voids
any current I
forcing the MAX7323 into the I
reset action does not clear the interrupt output (INT).
When the serial interface is idle, the MAX7323 automati-
cally enters standby mode, drawing minimal supply
current.
12
—
12
4
8
8
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.
Software equivalent to a MAX7320 plus a MAX7319.
Software equivalent to a MAX7320 plus a MAX7321.
Software equivalent to a MAX7320 plus a MAX7322.
Software equivalent to a MAX7320 plus a MAX7323.
POR
2
C transaction involving the MAX7323,
, the MAX7323 resets all ports to the
APPLICATION
2
C STOP condition. The
Initial Power-Up
Power-On Reset
Standby Mode
RST Input
2
C slave
POR