LTC4300-2CMS8#PBF

Overview

The LTC4300-2CMS8#PBF is a hot swappable 2-wire bus buffer designed for I2C and SMBus applications. It provides bidirectional buffering between backplane and card sides, isolating capacitances during live insertion. The device features separate supply pins: VCC for the backplane (2.7V to 5.5V) and VCC2 for the card side (2.7V to 5.5V), enabling level shifting between 3.3V and 5V systems without voltage constraints. It includes 1V precharge circuitry to minimize bus disturbances and rise time accelerators that inject 2mA transient current to meet timing requirements with weaker pull-ups. Operating frequency reaches 400kHz with propagation delays up to 75ns. Input capacitance is 10pF.

Feature Summary

• Bidirectional buffering isolates backplane and card capacitances during hot swapping
• Separate VCC and VCC2 supplies enable flexible level translation between 3.3V and 5V domains
• Rise time accelerator circuitry boosts pull-up currents to maintain signal integrity with high bus capacitance
• 1V precharge minimizes voltage differentials and bus corruption upon connector engagement

Applications

• Hot swapping I/O cards into live backplanes in servers and desktop computers
• Capacitance buffering and bus extending for I2C/SMBus lines
• Level translation between disparate 3.3V and 5V power supply domains

Procurement Notes

Verify the suffix CMS8 indicates the commercial temperature range of 0°C to 70°C and tube packaging. Confirm PBF denotes lead-free finish. Ensure the specific variant matches the required operating environment compared to the IMS8 industrial grade option. Cross-reference datasheet revision dates for any pinout or electrical characteristic updates before finalizing procurement orders.

Selection Notes

Select this model over the LTC4300-1 when independent control of card-side power is required via the VCC2 pin rather than an ENABLE logic input. Use the ACC pin to manage rise time accelerator activation. Verify that both VCC and VCC2 remain within the 2.7V to 5.5V range. Ensure bus capacitance meets minimum requirements for proper operation at the selected supply voltages.

Part Context

This component belongs to the LTC4300 series of hot swappable 2-wire bus buffers manufactured by Analog Devices Inc. The series includes variants like the LTC4300-1 which utilizes an ENABLE pin for shutdown control. The -2 variant specifically replaces the ENABLE pin with a dedicated VCC2 supply pin to facilitate level shifting applications between different voltage domains on the card and backplane sides.

Replacement Considerations

LTC4300-2IMS8#PBF offers the same functionality but supports an extended industrial temperature range of –40°C to 85°C.