pca9674a NXP Semiconductors, pca9674a Datasheet - Page 15

• Manufacturer Part Number: pca9674a
• Description: Remote 8-bit I/o Expander For Fm+ I2c-bus With Interrupt
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Product data sheet
PCA9674_PCA9674A_2
8.4 Power-on reset
8.5 Interrupt output (INT)
When power is applied to V
PCA9674/74A in a reset condition until V
condition is released and the PCA9674/74A registers and I
will initialize to their default states. Thereafter V
the device.
The PCA9674/74A provides an open-drain interrupt (INT) which can be fed to a
corresponding input of the microcontroller (see
gives these chips a kind of master function which can initiate an action elsewhere in the
system.
An interrupt is generated by any rising or falling edge of the port inputs. After time t
signal INT is valid.
The interrupt disappears when data on the port is changed to the original setting or data is
read from or written to the device which has generated the interrupt.
In the write mode, the interrupt may become deactivated (HIGH) on the rising edge of the
write to port pulse. On the falling edge of the write to port pulse the interrupt is definitely
deactivated (HIGH).
The interrupt is reset in the read mode on the rising edge of the read from port pulse.
During the resetting of the interrupt itself, any changes on the I/Os may not generate an
interrupt. After the interrupt is reset any change in I/Os will be detected and transmitted as
an INT.
Fig 16. Application of multiple PCA9674s with interrupt
MICROCOMPUTER
INT
Rev. 02 — 12 October 2006
DD
V
Remote 8-bit I/O expander for Fm+ I
DD
, an internal Power-On Reset (POR) holds the
PCA9674
device 1
INT
DD
has reached V
DD
Figure
PCA9674
device 2
must be lowered below 0.2 V to reset
INT
14,
Figure
POR
2
C-bus/SMBus state machine
PCA9674/74A
. At that point, the reset
15, and
2
C-bus with interrupt
© NXP B.V. 2006. All rights reserved.
Figure
PCA9674
device 8
002aac122
INT
16). This
v(D)
15 of 34
the