1. General description
The PCA9548A is an octal bidirectional translating switch controlled via the I
2
C-bus. The
SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any individual
SCx/SDx channel or combination of channels can be selected, determined by the
contents of the programmable control register.
An active LOW reset input allows the PCA9548A to recover from a situation where one of
the downstream I
2
C-buses is stuck in a LOW state. Pulling the RESET pin LOW resets
the I
2
C-bus state machine and causes all the channels to be deselected as does the
internal Power-on reset function.
The pass gates of the switches are constructed such that the V
DD
pin can be used to limit
the maximum high voltage which will be passed by the PCA9548A. This allows the use of
different bus voltages on each pair, so that 1.8 V or 2.5 V or 3.3 V parts can communicate
with 5 V parts without any additional protection. External pull-up resistors pull the bus up
to the desired voltage level for each channel. All I/O pins are 6 V tolerant.
2. Features and benefits
1-of-8 bidirectional translating switches
I
2
C-bus interface logic; compatible with SMBus standards
Active LOW reset input
Three address pins allowing up to eight devices on the I
2
C-bus
Channel selection via I
2
C-bus, in any combination
Power-up with all switch channels deselected
Low R
on
switches
Allows voltage level translation between 1.8 V, 2.5 V, 3.3 V and 5 V buses
No glitch on power-up
Supports hot insertion
Low standby current
Operating power supply voltage range of 2.3 V to 5.5 V
6 V tolerant inputs
0 Hz to 400 kHz clock frequency
ESD protection exceeds 2000 V HBM per JESD22-A114 and 1000 V CDM per
JESD22-C101
Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
Three packages offered: SO24, TSSOP24, and HVQFN24
PCA9548A
8-channel I
2
C-bus switch with reset
Rev. 5.1 — 1 October 2015 Product data sheet
