PCA9674_PCA9674A_2

© NXP B.V. 2006. All rights reserved.

Product data sheet

Rev. 02 — 12 October 2006

15 of 34

NXP Semiconductors

PCA9674/74A

8.4 Power-on reset

the device.

8.5 Interrupt output (INT)

The PCA9674/74A provides an open-drain interrupt (INT) which can be fed to a

corresponding input of the microcontroller (see Figure 14, Figure 15, and Figure 16). This

gives these chips a kind of master function which can initiate an action elsewhere in the

system.

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

002aac122

MICROCOMPUTER

INT

PCA9674

INT

PCA9674

INT

device 1

device 2

PCA9674

INT

device 8