Insulated bidirectional I2C bus communication technology based on LTC4310 design

Insulated bidirectional I2C bus communication technology based on LTC4310 design

LTC4310 is an isolated bidirectional I2C bus communication device from Linear. Each device can encode the I2C logic state into a signal and transmit it to another device through the insulation layer. The receiving device decodes and drives the I2C bus to the appropriate logic state. It is mainly used in isolated I2C, SMBus and PMBus interfaces, isolated power supply, Ethernet power supply and positive to negative power supply communication. This article introduces the main features of LTC4310, typical applications and various application circuit block diagrams.

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 main features: 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 Applications: Isolated I2C, SMB us and PMBus Interfaces Isolated Power Supplies Positive-to-Negative Rail Communications Power-over-EthernetFigure 1. LTC4310 Block DiagramLTC4310 Typical Applications: Figure 2. LTC4310 in 1500V Isolation I2C System Application Diagram Figure 3. LTC4310-1 in Transformer Isolation Application Diagram Figure 4. LTC4310-2 in 400 kHz Application Diagram Figure 5. LTC4310-1 in I2C Isolation Application Diagram between Ground Reference Bus and -5V Reference Bus Figure 6. LTC4310-1 in Zero Current Shutdown Application Diagram Figure 7. LTC4310-1 in I2C Hot Swap Application Diagram