4-CHANNEL I2C AND SMBUS SWITCH WITH RESET FUNCTION

DESCRIPTION

The UTC UCA9546 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 SCn/SDn

channel or combination of channels can be selected, determined

by the contents of the programmable control register.

An active-low reset ( RESET ) input allows the UTC UCA9546

to recover from a situation in which one of the downstream I2C

buses is stuck in a low state. Pulling RESET low resets the I2C

state machine and causes all the channels to be deselected, as

does the internal power-on reset function.

The pass gates of the switches are constructed such that the

VCC pin can be used to limit the maximum high voltage which is

passed by the UCA9546. 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 5V 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 5.5V tolerant.

FEATURES

* 1-of-4 Bidirectional Translating Switches

* I2C Bus and SMBus Compatible

* Active-Low Reset Input

* 3 Address Pins, Allowing up to Eight Devices on the I2C Bus

* Channel Selection Via I2C Bus

* 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 2.3 V to 5.5 V

* 5.5V Tolerant Inputs

* 0 to 400kHz Clock Frequency