text.skipToContent text.skipToNavigation


Hot Swappable 2-Wire Bus Buffers


Package | PIN: D | 8
Temp: I (-40 to 85)
Carrier: Cut Tape
Qty Price
1-9 $1.16
10-24 $1.04
25-99 $0.97
100-249 $0.84
250-499 $0.78
500-749 $0.65
750-999 $0.53
1000+ $0.49


  • 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 MachineModel (A115-A)
    • 1000-V Charged-Device Model (C101)

All trademarks are the property of their respective owners.

Texas Instruments  TCA4311ADR

The TCA4311A is a hot-swappable I2C bus buffer that supportsI/O card insertion into a live backplane without corruption of the data and clock busses. Controlcircuitry prevents the backplane from being connected to the card until a stop command or bus idleoccurs on the backplane without bus contention on the card. When the connection is made, thisdevice 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 tocharge the parasitic capacitance of the chip.

When the I2C bus is idle, the TCA4311A can be put intoshutdown mode by setting the EN pin low. When EN is high, the TCA4311A resumes normal operation. Italso includes an open drain READY output pin, which indicates that the backplane and card sides areconnected 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 5.5V, 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/Osdepends on the system, but each side of this buffer must have a pull-up resistor. The device isdesigned to work with Standard Mode and Fast Mode I2C devices inaddition to SMBus devices. Standard Mode I2C devices only specify 3 mAin a generic I2C system where Standard Mode devices and multiple mastersare possible. Under certain conditions, high termination currents can be used.