pca9670 NXP Semiconductors, pca9670 Datasheet - Page 15

• Manufacturer Part Number: pca9670
• Description: Pca9670 Remote 8-bit I/o Expander For Fm I?c-bus With Reset
• Manufacturer: NXP Semiconductors

NXP Semiconductors
10. Application design-in information
PCA9670_2
Product data sheet
10.1 Bidirectional I/O expander applications
10.2 High current-drive load applications
In the 8-bit I/O expander application shown in
P7 are outputs. When used in this configuration, during a write, the input (P0 and P1)
must be written as HIGH so the external devices fully control the input ports. The desired
HIGH or LOW logic levels may be written to the I/Os used as outputs (P2 to P7). During a
read, the logic levels of the external devices driving the input ports (P0 and P1) and the
previous written logic level to the output ports (P2 to P7) will be read.
The GPIO also has a reset line (RESET) that can be connected to an output pin of the
microprocessor. Since the device does not have an interrupt output, changes of the I/Os
can be monitored by reading the input register. If both a RESET and INT are needed, use
the PCA9671.
The GPIO has a maximum sinking current of 25 mA per bit. In applications requiring
additional drive, two port pins in the same octal may be connected together to sink up to
50 mA current. Both bits must then always be turned on or off together. Up to 8 pins (one
octal) can be connected together to drive 200 mA.
Fig 18. Bidirectional I/O expander application
Fig 19. High current-drive load application
PROCESSOR
CORE
PROCESSOR
CORE
Rev. 02 — 17 July 2007
V
DD
V
DD
Remote 8-bit I/O expander for Fm+ I
SDA
SCL
RESET
AD0
AD1
AD2
V
SDA
SCL
RESET
AD0
AD1
AD2
DD
Figure
V
P0
P1
P2
P3
P4
P5
P6
P7
DD
P0
P1
P2
P3
P4
P5
P6
P7
18, P0 and P1 are inputs, and P2 to
temperature sensor
battery status
control for latch
control for switch
control for audio
control for camera
control for MP3
002aac299
LOAD
V
DD
002aac298
PCA9670
© NXP B.V. 2007. All rights reserved.
2
V
C-bus with reset
DD
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