PCA9557
NXP Semiconductors
8-bit I2C-bus and SMBus I/O port with reset
data from
shift register
configuration
register
data from
shift register
D
Q
output port
register data
FF
write configuration
pulse
D
Q
CK
Q
FF
IO0
write pulse
CK
ESD protection
diode
output port
register
V
SS
input port
register
D
Q
input port
register data
FF
CK
read pulse
polarity inversion
register
data from
shift register
polarity inversion
register data
D
Q
FF
write polarity
pulse
CK
002aad277
On power-up or reset, all registers return to default values.
Fig 2. Simplified schematic of IO0
PCA9557
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© NXP B.V. 2013. All rights reserved.
Product data sheet
Rev. 7 — 10 December 2013
3 of 30
NXP [ NXP ]
