General description

     The AT9546A is a quad bidirectional translating switch controlled via the I²C-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 AT9546A to recover fro m a situation where one of the downstream I²C-buses is stuck in a LOW state. Pulling the RESET pin LOW resets the I²C-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 AT9546A. This allows the use of different bus voltages on each pair, so that 1.8V or 2.5V or 3.3V 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 5V tolerant.

Features and benefits

1-of-4 bidirectional translating switches

I²C-bus interface logic; compatible with SMBus standards 

Active LOW reset input

3 address pins allowing up to 8 devices on the I²C-bus

Channel selection via I²C-bus, in any combination

Power-up with all switch channels deselected 

Low Ron switches 

Allows voltage level translation between 1.8V, 2.5V, 3.3V and 5V buses 

No glitch on power-up 

Supports hot insertion 

Low standby current 

Operating power supply voltage range of 2.3V to 5.5V 

5V tolerant Inputs 

0Hz 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

Block diagram