1 Features

1• Operating Power-Supply Voltage Range of 2.7 V

to 5.5 V

• Supports Bidirectional Data Transfer of I2C Bus

Signals

• SDA and SCL Lines are Buffered Which Increases

Fanout

• 1-V Precharge on all SDA and SCL Lines

Prevents Corruption During Live Board Insertion

and Removal From Backplane

• SDA and SCL Input Lines are Isolated From

Outputs

• Accommodates Standard Mode and Fast Mode

I2C Devices

• Improved Noise Immunity

• Applications Include Hot Board Insertion and Bus

Extension

• Low ICC Chip Disable of < 1 μA

• READY Open-Drain Output

• Supports Clock Stretching, Arbitration, and

Synchronization

• Powered-Off High-Impedance I2C Pins

• Open-Drain I2C Pins

• Latch-Up Performance Exceeds 100 mA Per

JESD 78, Class II

• ESD Protection Exceeds JESD 22

– 8000-V Human-Body Model (A114-A)

– 200-V Machine Model (A115-A)

– 1000-V Charged-Device Model (C101)

2 Applications

• Servers

• Routers (Telecom Switching Equipment)

• Base Stations

• Industrial Automation

3 Description

The TCA4311A is a hot-swappable I2C bus buffer

that supports I/O card insertion into a live backplane

without corruption of the data and clock busses.

Control circuitry prevents the backplane from being

connected to the card until a stop command or bus

idle occurs on the backplane without bus contention

on the card. When the connection is made, this

device provides bidirectional buffering, keeping the

backplane and card capacitances isolated. During

insertion, the SDA and SCL lines are pre-charged to

1 V to minimize the current required to charge the

parasitic capacitance of the chip.

When the I2C bus is idle, the TCA4311A can be put

into shutdown mode by setting the EN pin low. When

EN is high, the TCA4311A resumes normal operation.

It also includes an open drain READY output pin,

which indicates that the backplane and card sides are

connected together. When READY is high, the

SDAIN and SCLIN are connected to SDAOUT and

SCLOUT. When the two sides are disconnected,

READY is low.

Both the backplane and card may be powered with

supply voltages ranging from 2.7 V to 5.5 V, with no

restrictions on which supply voltage is higher.

The TCA4311A has standard open-drain I/Os. The

size of the pull-up resistors to the I/Os depends on

the system, but each side of this buffer must have a

pull-up resistor. The device is designed to work with

Standard Mode and Fast Mode I2C devices in

addition to SMBus devices. Standard Mode I2C

devices only specify 3 mA in a generic I2C system

where Standard Mode devices and multiple masters

are possible. Under certain conditions, high

termination currents can be used.