LTC4309IDE Hot Swappable Two Wire Bus Buffer with Stuck Bus Recovery DFN-12 Integrated Chip

The LTC4309 is a hot swappable 2-wire bus buffer in a DFN-12 package that allows an I/O card to be inserted into or removed from a live backplane without corrupting the data and clock lines.

Buffering is bidirectional with a 60 mV offset that stays constant regardless of load, so multiple buffers can be cascaded without eating into the logic low margin.

Level shifting covers 2.5 V, 3.3 V and 5 V busses, and the input side stays isolated from the output side until a stop bit or bus idle condition confirms the bus is free. All SDA and SCL lines are precharged to 1 V during insertion.

If SDAOUT or SCLOUT stay low for 30 ms, FAULT pulls low, and with DISCEN high the part breaks the connection and generates up to 16 clocks and a stop bit to release the bus, reconnecting once the fault clears.

The LTC4309 is rated to plus or minus 6 kV HBM ESD, operates over -40 to +85 degree C, is RoHS compliant and ships with full traceability. Samples and volume pricing are available on request.

• LTC4309IDE hot swappable 2-wire bus buffer for live insertion in DFN-12 package
• LTC4309 series in stock with full traceability and volume pricing
• Bidirectional buffering increases fan-out
• 60 mV buffer offset independent of load
• Level shift between 2.5 V, 3.3 V and 5 V busses
• Compatible with non-compliant low VOL I2C devices
• Isolates input SDA and SCL lines from the output side
• Optional disconnect when the bus is stuck low
• 30 ms stuck bus timeout with FAULT open-drain output
• Up to 16 clock pulses and a stop bit to free the bus
• READY open-drain output for connection status
• 1 V precharge on all SDA and SCL lines during insertion
• Optional rise time accelerators enabled by the ACC pin
• High impedance SDA and SCL pins when VCC is zero
• Plus or minus 6 kV human body model ESD ruggedness

• Live insertion of I/O cards
• Server, storage and telecom backplanes
• Cascaded I2C bus segments
• Level shifting between 3.3 V and 5 V buses
• Bus isolation for hot swap modules

Typical use is digitally controlled resistance and divider trimming in surface mount assemblies.

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