原标题：Linear LTC4313 I2C总线热插拔应用方案

　　Linear公司的LTC4313是热插拔两线双向总线缓冲器, 噪音容限高达0.3VCC,支持电压1.5V, 1.8V, 2.5V, 3.3V 和5V,在插入时, SDA和SCL线能预充电到1V以最小化对总线的干扰.器件和I2C,I2C快速模式和SMBus兼容, ±4kV人体模式ESD保护,主要用在容性缓冲器/总线扩展器,板热插拔,包括ATCA的通信系统,电平转换,PMBus和服务器.本文介绍了 LTC4313主要特性,方框图,以及多种应用电路.

　　The LTC4313 is a hot swappable 2-wire bus buffer that provides bidirectional buffering while maintaining a low offset voltage and high noise margin up to 0.3 • VCC. The high noise margin allows the LTC4313 to be interoperable with devices that drive a high VOL (>0.4V) and allows multiple LTC4313s to be cascaded. The LTC4313-1 and LTC4313-2 support level translation between 3.3V and 5V busses. In addition to these voltages, the LTC4313-3 also supports level translation to 1.5V, 1.8V and 2.5V.

　　During insertion, the SDA and SCL lines are pre-charged to 1V to minimize bus disturbances. Connection is established between the input and output after ENABLE is asserted high and a stop bit or bus idle condition has been detected on the SDA and SCL pins. If both data and clock are not simultaneously high at least once in 45ms, the input is disconnected from the output. Up to 16 clock pulses are subsequently generated to free the stuck bus. Rise time accelerators (RTAs) provide pull-up currents on SDA and SCL rising edges to meet rise time specifications in heavily loaded systems. The RTAs are configured as slew limited switches in the LTC4313-1 and 2.5mA current sources in the LTC4313-2. The LTC4313-3 does not have RTAs.

　　LTC4313主要特性:

　　Bidirectional Buffer Increases Fanout

　　High Noise Margin with VIL = 0.3•VCC

　　Compatible with Non-Compliant I2C Devices That Drive a High VOL

　　Strong (LTC4313-1) and 2.5mA (LTC4313-2) Rise Time Accelerator Current

　　Level Shift 1.5V, 1.8V, 2.5V, 3.3V and 5V Busses

　　Prevents SDA and SCL Corruption During Live Board Insertion and Removal from Backplane

　　Stuck Bus Disconnect and Recovery

　　Compatible with I2C, I2C Fast Mode and SMBus

　　±4kV Human Body Model ESD Ruggedness

　　High Impedance SDA, SCL Pins When Unpowered

　　8-Lead MSOP and 8-Lead (3mm × 3mm) DFN Packages

　　LTC4313应用:

　　Capacitance Buffers/Bus Extender

　　Live Board Insertion

　　Telecommunications Systems Including ATCA

　　Level Translation

　　PMBus

　　Servers

　　图1. LTC4313方框图

　　图2. LTC4313典型应用电路图

　　图3. LTC4313带连接器的I2C热插拔应用电路图

　　图4.采用LTC4313-3从3.3V到1.8V的电平转移电路图

　　图5.LTC4313在总线ATCA中应用电路(仅显示一路时钟)

　　图6.LTC4313-2在放射状地连接(6x4列)通信系统的应用

　　图7.LTC4313-1和其它LTC缓冲器级联的应用电路

　　图8.LTC4313和非兼容I2C器件的通信

　　图9.LTC4313在转发器中的应用