Unstuck bus

Linear Technology Corporation

has introduced the LTC4303 and LTC4304 2-wire bus buffers with stuck bus recovery. These new ICs are said to solve the common problem of a stuck bus by isolating all of the bus connections on the upstream side, while restoring the downstream bus. If the serial data output SDAOUT or serial clock output SCLOUT are low for more than 30ms, the LTC4304 will automatically break the data and clock connections, issuing a Fault signal.

Sequentially, the LTC4304 will automatically generate up to 16 clock pulses on the SCLOUT in an attempt to free the bus. When the bus becomes free, a connection is immediately enabled and proper operation resumes. With stuck bus recovery, the LTC4303 and LTC4304 eliminate the need for a general system reset and unburden the microcontroller, providing the appropriate signals to free the bus.

The LTC4303 and LTC4304 also provide capacitive isolation between the backplane and the card's I2C busses, even if their respective supplies are at different levels. The ICs perform this level translation without the need of a second supply pin or a second pair of input pull-up resistors, eliminating the requirement to dedicate a connector pin for the backplane supply voltage.