Demonstration circuit 757-A/-B features the LTC4302- 1/LTC4302-2, an Addressable 2-Wire I²C bus and SMBus compatible Bus Buffer. The LTC4302-1/LTC4302-2 allows a peripheral board to be inserted and removed from a live backplane without corruption of the bus. The LTC4302-1/LTC4302-2 maintain electrical isolation between the backplane and peripheral board until their VCC supply is valid and a master device on the backplane side addresses the LTC4302-1/LTC4302-2 and commands them to connect. The LTC4302-1/LTC4302-2 ADDRESS pin provides 32 possible addresses set by an external resistive divider between VCC and GND. The LTC4302-1/LTC4302-2 work with supply voltages ranging from 2.7V to 5.5V. The SDA and SCL inputs and outputs do not load the bus lines when VCC is low. Rise time accelerator circuitry allows for heavier capacitive bus loading while still meeting system timing requirements. During insertion, the SDA and SCL lines are precharged to 1V to minimize bus disturbances. Two general purpose input/output pins (GPIOs) on the LTC4302-1 can be configured as inputs, open-drain outputs or push-pull outputs. The status of a GPIO is displayed with an LED on the DC757-A/-B. The LTC4302-2 option replaces one GPIO pin with a second supply voltage pin VCC2, providing level shifting between systems with different supply voltages. The DC757-A/-B is a part of the QuickEval systems which allows for quick and easy evaluation of the LTC4302-1/LTC4302-2 with a software interface.