描述 Description

The PCA9545A/45B/45C is a quad bidirectional translating switch controlled via theI2C-bus. The SCL/SDA upstream pair fans out to four downstream pairs, or channels. Anyindividual SCx/SDx channel or combination of channels can be selected, determined bythe contents of the programmable control register. Four interrupt inputs, INT0 to INT3, onefor each of the downstream pairs, are provided. One interrupt output, INT, acts as an ANDof the four interrupt inputs.
An active LOW reset input allows the PCA9545A/45B/45C to recover from a situationwhere one of the downstream I2C-buses is stuck in a LOW state. Pulling the RESET pinLOW resets the I2C-bus state machine and causes all the channels to be deselected asdoes the internal power-on reset function.
The pass gates of the switches are constructed such that the VDD pin can be used to limitthe maximum high voltage which is passed by the PCA9545A/45B/45C. This allows theuse of different bus voltages on each pair, so that 1.8 V or 2.5 V or 3.3 V parts cancommunicate with 5 V parts without any additional protection. External pull-up resistorspull the bus up to the desired voltage level for each channel. All I/O pins are 5 V tolerant.
The PCA9545A, PCA9545B and PCA9545C are identical except for the fixed portion ofthe slave address.

特性 Features

1-of-4 bidirectional translating switches
I2C-bus interface logic; compatible with SMBus standards
4 active LOW interrupt inputs
Active LOW interrupt output
Active LOW reset input
2 address pins allowing up to 4 devices on the I2C-bus
Alternate address versions A, B and C allow up to a total of 12 devices on the bus for larger systems or to resolve address conflicts
Channel selection via I2C-bus, in any combination
Power-up with all switch 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 protection exceeds 100 mA per JESD78
Three packages offered: SO20, TSSOP20, and HVQFN20