专用接口, I2C, SMBus, I2C总线与SMBus系统应用, 2.3 V, 5.5 V, TSSOP, 8 引脚
Overview
The PCA9540B is a 1-of-2 bidirectional translating multiplexer, controlled via the I²C-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 I²C-bus state machine with no channels selected.
The pass gates of the multiplexer are constructed such that the VDD 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.
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## Features
* 1-of-2 bidirectional translating multiplexer
* I²C-bus interface logic; compatible with SMBus standards
* Channel selection via I²C-bus
* Power-up with all multiplexer channels deselected
* Low Ron 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
## Features