LTC4300A-2CMS8#TRPBF

Overview

The LTC4300A-2CMS8#TRPBF is a hot swappable 2-wire bus buffer manufactured by Analog Devices Inc. It operates within a supply voltage range of 2.7V to 5.5V and supports data rates up to 400kHz. The device features bidirectional buffering for SDA and SCL lines, isolating backplane and card capacitances during live insertion. It includes rise-time accelerator circuitry that provides transient boosted pull-up currents, typically 12mA, to meet system requirements with weaker DC pull-ups. The component utilizes a dedicated VCC2 pin for level shifting between 3.3V and 5V systems and incorporates a 1V precharge function on all SDA and SCL lines to minimize bus disturbances.

Feature Summary

• Provides bidirectional buffering while isolating backplane and card capacitances during live board insertion
• Features rise-time accelerator circuitry to allow the use of weaker DC pull-up currents
• Includes a dedicated VCC2 supply pin enabling level shifting between 3.3V and 5V systems
• Precharges SDA and SCL lines to 1V to minimize bus disturbances during connection

Applications

• Bidirectional buffer for SDA and SCL lines in I/O card insertion applications
• Servers requiring hot-swappable interface capabilities
• Desktop computer systems utilizing I2C or SMBus standards
• Capacitance buffering and bus extension scenarios

Procurement Notes

Verify the specific ordering suffix TRPBF indicates tape and reel packaging when sourcing this component. Confirm the CMS8 designation corresponds to the commercial temperature range of 0°C to 70°C. Ensure compatibility with the 8-lead MSOP package dimensions for PCB layout. Cross-reference the manufacturer part number with official distributor catalogs to confirm current availability status.

Selection Notes

Select the LTC4300A-2 variant specifically when level shifting between disparate supply voltages, such as 3.3V and 5V, is required. This model replaces the ENABLE pin found in the -1 variant with a VCC2 supply pin and an ACC input for controlling rise-time accelerators. Ensure the application does not require the low current disable feature provided by the ENABLE pin on the -1 version.

Part Context

This component belongs to the LTC4300A series of hot swappable 2-wire bus buffers. It shares core functionality with the LTC4300A-1 but differs in control architecture. The -2 variant is designed for systems needing independent supply rails for the backplane and card sides, whereas the -1 uses a single supply and digital enable control.

Replacement Considerations

LTC4300A-1CMS8#TRPBF: Replaces if level shifting is not needed and digital enable control is preferred.

FAQ

How does the LTC4300A-2 handle level shifting?

It uses a dedicated VCC2 pin for the card side supply, allowing independent voltage levels ranging from 2.7V to 5.5V on both VCC and VCC2 without constraints on which is higher.

What is the function of the ACC pin?

The ACC pin is a digital CMOS input that enables or disables the rise-time accelerator currents on all four SDA and SCL pins.

How does the device protect against bus corruption during insertion?

It precharges the SDA and SCL lines to 1V before connection and isolates the backplane and card capacitances until the start-up sequence is complete.