LTC4308IDD#PBF

Signal Buffers, Repeaters, Splitters Overview

The LTC4308IDD#PBF is a low voltage, level shifting hot swappable 2-wire bus buffer with stuck bus recovery. It supports I2C and SMBus protocols with a maximum operating frequency of 600 kHz. The supply voltage range is 2.3 V to 5.5 V, with a typical supply current of 7 mA. Propagation delay is 70 ns (high-to-low) and 10 ns (low-to-high). Input capacitance is 10 pF. The device operates from -40°C to +85°C and is housed in an 8-lead DFN package.

Signal Buffers, Repeaters, Splitters Feature Summary

• Bidirectional buffering isolates input and output bus capacitances during live board insertion.
• Automatic stuck bus recovery generates clock pulses to release locked buses after a 30ms timeout.
• Level shifting capability allows communication between high VOL devices and low voltage inputs down to 0.9V.
• Rise time accelerators provide boosted pull-up currents to ensure fast signal transitions on the output bus.

Signal Buffers, Repeaters, Splitters Applications

• Live board insertion into servers and backplanes
• RAID systems requiring hot-swappable I/O cards
• ATCA architectures
• Capacitance buffering for bus extension

Signal Buffers, Repeaters, Splitters Procurement Notes

Verify the ordering suffix matches the required temperature grade and packaging format. The IDD suffix indicates the industrial temperature range (-40°C to +85°C). Confirm the PBF suffix denotes lead-free finish and RoHS compliance. Ensure the DFN package type aligns with the PCB footprint design requirements.

Signal Buffers, Repeaters, Splitters Selection Notes

Select this component when hot swapping capabilities and automatic bus recovery are required. Verify that the system bus capacitance and pull-up resistor values allow the rise time accelerators to activate properly. Ensure the minimum supply voltage meets the 2.3 V requirement for reliable operation across the full temperature range.

Signal Buffers, Repeaters, Splitters Part Context

This part belongs to the LTC4308 family of hot swappable bus buffers. It is functionally similar to the LTC4301L but includes additional features such as automatic stuck bus recovery and rise time accelerators. The IDD variant specifically covers the industrial temperature range and uses the DFN package.

Signal Buffers, Repeaters, Splitters Replacement Considerations

When replacing an LTC4301L, account for the active-high ENABLE pin versus the active-low CS pin. Verify that the lower minimum supply voltage of 2.3 V is compatible with the system power rails. Ensure the application can tolerate the automatic clock generation during stuck bus recovery events.

Signal Buffers, Repeaters, Splitters FAQ

How does the LTC4308 handle a stuck bus condition?

If SDAOUT or SCLOUT remains low for 30ms, the device disconnects the input-output connection and generates up to 16 clock pulses on SCLOUT to attempt to free the bus.

What is the purpose of the READY pin?

READY is an open-drain output that indicates whether the input and output busses are connected. It goes low when ENABLE is low or during a stuck bus disconnection event.

Can the LTC4308 interface between different voltage levels?

Yes, it provides bidirectional level shifting between bus supplies as low as 0.9V and up to 5.5V, utilizing negative offset voltages to maintain compatibility.