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
• Applications Include Hot Board Insertion and Bus
Extension
• Low I CC 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 Description
The TCA4311 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 precharged to 1 V to minimize the current required to charge the
parasitic capacitance of the chip.
When the I2C bus is idle, the TCA4311 can be put
into shutdown mode by setting the EN pin low. When
EN is high, the TCA4311 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 TCA4311 has standard open-drain I/Os. The size
of the pullup resistors to the I/Os depends on the
system, but each side of this buffer must have a
pullup 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.