PCA9675 Datasheet, PDF (16/34 Pages) NXP Semiconductors – Remote 16-bit I/O expander for Fm+ I2C-bus with interrupt

NXP Semiconductors
PCA9675
Remote 16-bit I/O expander for Fm+ I²C-bus with interrupt
8.4 Power-on reset
When power is applied to V_DD, an internal Power-On Reset (POR) holds the PCA9675 in
a reset condition until V_DD has reached V_POR. At that point, the reset condition is released
and the PCA9675 registers and I²C-bus/SMBus state machine will initialize to their default
states. Thereafter V_DD must be lowered below 0.2 V to reset the device.
8.5 Interrupt output (INT)
The PCA9675 provides an open-drain interrupt (INT) which can be fed to a corresponding
input of the microcontroller (see Figure 17, Figure 18, and Figure 19). This 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_(v)D the
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.
V_DD
MICROCOMPUTER
INT
device 1
PCA9675
INT
device 2
PCA9675
INT
Fig 19. Application of multiple PCA9675s with interrupt
device 8
PCA9675
INT
002aab635
PCA9675_1
Product data sheet
Rev. 01 — 1 February 2007
© NXP B.V. 2007. All rights reserved.
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