General Description

The DS3205 bus buffer enables hot insertion and extraction of boards without corruption of the backplane’s 2-wire bus (I2C, SMBus™, IPMI, etc.). When a board is inserted, the DS3205 presents highimpedance SCL and SDA connections to the backplane until VDD rises above 2.5V. During normal operation, the DS3205 provides bidirectional buffering to keep backplane and board capacitances isolated.

Features

♦ Compliant to PICMG 3.0 IPMI I2C Requirements

♦ Bidirectional Buffer for SCL and SDA Lines

♦ Compatible with I2C, I2C Fast Mode, SMBus, IPMI, and ATCA® Standards (Up to 400kHz)

♦ Prevents Corruption of System SCL and SDA Lines During Live Insertion/Removal of Boards

♦ Increases Fanout by Connecting Board Bus to Backplane Bus with < 10pF Additional Load

♦ Automatically Delays Initial Bus Connection Until Both Bus Segments Are Idle

♦ SCL and SDA Pins High-Z When VDD = 0V

♦ 1V Precharge on SCL and SDA Lines

♦ ENABLE Input Pin Connects or Isolates Buses

♦ READY Output Pin Indicates “Connected”

♦ FAULT Output Pin Indicates “Stuck Bus”

♦ Optional Rise-Time Accelerators on All Bus Pins

♦ Configurable Rise-Time Accelerator Slew Rate Threshold (0.8V/μs or 1.25V/μs)

♦ Supports Clock Stretching and Multiple Bus Master Arbitration and Synchronization

♦ Optionally Disconnects Board from Backplane When Bus is Stuck Low for ≥ 30ms

♦ Optionally Attempts to Recover a Stuck Bus by Clocking Board SCL

♦ ±15kV ESD Protection (Human Body Model) on Bus Pins

♦ Wide Operating Voltage Range: 2.7V to 5.5V

♦ 5V Tolerant I/Os

♦ Tiny 14-Pin, 3mm x 3mm TDFN Package

Applications

    Hot-Swappable Boards for AdvancedTCA®, CompactPCI®, VME, and Other Backplanes in Chassis-Oriented Telecom, Datacom, Computing, and Storage Systems

    Capacitance Buffer

    Bus Extender

    Fault Isolator