Datasheet

1. General description
The PCA9540B is a 1-of-2 bidirectional translating multiplexer, controlled via the I
2
C-bus.
The SCL/SDA upstream pair fans out to two SCx/SDx downstream pairs, or channels.
Only one SCx/SDx channel is selected at a time, determined by the contents of the
programmable control register.
A power-on reset function puts the registers in their default state and initializes the I
2
C-bus
state machine with no channels selected.
The pass gates of the multiplexer are constructed such that the V
DD
pin can be used to
limit the maximum high voltage that is passed by the PCA9540B. This allows the use of
different bus voltages on each SCx/SDx pair, so that 1.8 V, 2.5 V or 3.3 V parts can
communicate with 5 V parts without any additional protection. External pull-up resistors
can pull the bus up to the desired voltage level for this channel. All I/O pins are 5 V
tolerant.
2. Features and benefits
 1-of-2 bidirectional translating multiplexer
 I
2
C-bus interface logic; compatible with SMBus standards
 Channel selection via I
2
C-bus
 Power-up with all multiplexer 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
 Packages offered: SO8, TSSOP8, XSON8
PCA9540B
2-channel I
2
C-bus multiplexer
Rev. 6 — 5 May 2014 Product data sheet