1. General description
The PCA9546A is a quad bidirectional translating switch controlled via the I
2
C-bus. The
SCL/SDA upstream pair fans out to four 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 PCA9546A 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 (POR) 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 is passed by the PCA9546A. 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 5 V tolerant.
2. Features and benefits
1-of-4 bidirectional translating switches
I
2
C-bus interface logic; compatible with SMBus standards
Active LOW reset input
3 address pins allowing up to 8 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
5 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: SO16, TSSOP16, and HVQFN16
PCA9546A
4-channel I
2
C-bus switch with reset
Rev. 6 — 30 April 2014 Product data sheet
