CAT9554 CATALYST [Catalyst Semiconductor], CAT9554 Datasheet - Page 7

• Manufacturer Part Number: CAT9554
• Description: 8-bit I2C and SMBus I/O Port with Interrupt
• Manufacturer: CATALYST [Catalyst Semiconductor]

Configuration Pulse
INT: Interrupt Output
The open-drain interrupt output is activated when one of
the port pins configured as an input changes state
(differs from the corresponding input port register bit
state). The interrupt is deactivated when the input returns
© 2006 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
Shift Register
Shift Register
Shift Register
Read Pulse
Write Pulse
Data from
Data from
Data from
Register
Polarity
Write
Write
Configuration
C K
D
Register
FF
Q
Q
Figure 4. Simplified Schematic of I/O
C K
D
Output Port
Register
FF
Q
Q
7
to its previous state or the input port register is read.
Changing an I/O from an output to an input may cause
a false interrupt if the state of the pin does not match the
contents of the input port register.
Inversion Register
C K
C K
D
D
Input Port
Register
LATCH
Polarity
FF
Q
Q
Q
Q
0
to I/O
Q1
7
Q2
CAT9554, CAT9554A
Doc. No. 25088, Rev. B
Output Port
Register Data
I/O
Input Port
Register Data
Polarity
Register Data
V CC
V SS
To INT
0
to I/O
7