The LTC4303 and LTC4304 two-wire bus buffers from Linear Technology solve the common problem of a stuck I2C/SMBus 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 30 ms, the LTC4304 will automatically break the data and clock connections and issue a Fault signal. (The LTC4303 does not provide the Fault Flag for a stuck bus.) Next, it will automatically generate up to 16 clock pulses on the SCLOUT pin in an attempt to free the bus. Freeing the bus immediately enables a connection, and proper operation resumes. With stuck bus recovery, the LTC4303 and LTC4304 can eliminate the need for a general system reset and unburden the microcontroller.
The LTC4303 is housed in an MSOP-8 or 3- by 3-mm DFN package. It's pin-compatible with the LTC4300A-1. The LTC4304 comes in an MSOP-10 or the same 3- by 3-mm DFN package. Both are available in commercial or industrial temperature-range versions. Prices start at $2.10 each in lots of 1000.
Linear Technology Corp.