基于LTC4310設計的絕緣雙向I2C總線通信技術

LTC4310是Linear 公司的絕緣的雙向I2C總線通信器件，每個器件可把I2C邏輯狀態編碼成信號，通過絕緣層傳輸到另一個器件．接收器件解碼，并驅動I2C總線到適當的確邏輯狀態．主要用在絕緣的I2C， SMBus和PMBus 接口，絕緣電源，以太網供電和正到負電源通信．本文介紹了LTC4310主要特性，典型應用以及多種應用電路框圖．

The LTC?4310 provides bidirectional I2C communications between two I2C buses whose grounds are isolated from one another. Each LTC4310 encodes I2C bus logic states into signals that are transmitted across an isolation barrier to another LTC4310. The receiving LTC4310 decodes the transmission and drives its l2C bus to the appropriate logic state. The isolation barrier can be bridged by an inexpensive Ethernet， or other transformer， to achieve communications across voltage differences reaching thousands of volts， or it can be bridged by capacitors for lower voltage isolation. The LTC4310-1 is intended for use in 100kHz I2C systems. The LTC4310-2 is intended for 400kHz I2C systems.

Rise time accelerators provide strong pull-up currents on SCL and SDA rising edges to meet rise time specifications for heavily loaded systems. Data and clock Hot Swap? circuitry prevent data corruption when a card is inserted into or removed from a live bus. When a bus is stuck low for 37ms， the LTC4310 turns off its pull-down devices and generates up to sixteen clocks and a STOP bit in an attempt to free the bus. Driving EN low sets the LTC4310 in a very low current shutdown mode to conserve power.

LTC4310主要特性：

Bidirectional I2C Communication Between Two Isolated Buses

Full Isolation with Inexpensive Ethernet Transformers or Capacitors

Low Voltage Level Shifting

I2C Maximum Operating Frequency：

100kHz for LTC4310-1

400kHz for LTC4310-2

I2C Specification Compliant VOL， VIL

±5kV Human Body Model ESD Protection

Rise Time Accelerators

SDA， SCL Hot-Swapping

Very Low Shutdown Current

Stuck Bus Disconnect and Recovery

Thermal Shutdown

10-Lead MSOP and 3mm × 3mm DFN Packages

LTC4310應用：

Isolated I2C， SMBus and PMBus Interfaces

Isolated Power Supplies

Positive-to-Negative Rail Communications

Power-over-Ethernet

圖１．LTC4310方框圖

LTC4310典型應用：

圖２．LTC4310在1500V絕緣I2C系統應用框圖

圖３．LTC4310-１在變壓器絕緣應用框圖

圖4．LTC4310-2在400 kHz的應用框圖

圖5．LTC4310-１在地參考總線和-5V參考總線間的I2C絕緣應用框圖

圖６．LTC4310-１在零電流關斷下應用框圖

圖７．LTC4310-１在I2C熱插拔應用框圖