Level Shifting Hot Swappable 2-Wire Bus Buffer with Enable

The LTC4300A-3 hot swappable 2-wire bus buffer allows I/O card insertion into a live backplane without corruption of the data and clock busses. When the connection is made, the LTC4300A-3 provides bidirectional buffering, keeping the backplane and card capacitances isolated. Rise-time accelerator circuitry allows the use of weaker DC pull-up currents while still meeting rise-time requirements. During insertion, the SDA and SCL lines are precharged to 1V to minimize bus disturbances.

The LTC4300A-3 provides level translation between 3.3V and 5V supplies. The backplane and card can both be powered with supplies ranging from 2.7V to 5.5V. The LTC4300A-3 also incorporates a CMOS threshold ENABLE pin which forces the part into a low current mode and isolates the card from the backplane. When driven to VCC, the ENABLE pin sets normal operation.

The LTC4300A-3 is available in the MSOP and 3mm × 3mm DFN packages.

*Patent pending.

Applications

* Hot Board Insertion

* Servers

* Capacitance Buffer/Bus Extender

* Desktop Computer

* Bidirectional Buffer* for SDA and SCL Lines Increases Fanout* Prevents SDA and SCL Corruption During Live Board Insertion and Removal From Backplane* Logic Threshold ENABLE Input* Isolates Input SDA and SCL Lines from Output* Compatible with I2C, I2C Fast Mode and SMBus Standards (Up to 400kHz Operation)* 1V Precharge on all SDA and SCL Lines* Supports Clock Stretching, Arbitration and Synchronization* 5V to 3.3V Level Translation* High Impedance SDA, SCL Pins for VCC = 0V, VCC2 = 0V* Small 8-Lead DFN and MSOP Packages