DC1079A-A Analog Devices

DEMO MANUAL DC1079A-A/DC1079A-B LTC4310-1/LTC4310-2 2 Hot Swappable I C Isolators DESCRIPTION 2 Demonstration circuit 1079A features the LTC4310 I C for 37ms, the LTC4310 turns off its pull-down devices 2 isolator. The LTC 4310 provides bidirectional I C com- and generates up to sixteen clocks and a STOP bit in an 2 munication between two I C buses whose grounds are attempt to free the bus. Driving EN low sets the LTC4310 2 isolated from one another. Each LTC4310 encodes I C in a very low current shutdown mode to conserve power. bus logic states into signals that are transmitted across This is set with a jumper for each LTC4310 on the DC1079A. an isolation barrier to another LTC4310. The receiving The READY pin provides a digital output flag that pulls low 2 LTC4310 decodes the transmission and drives its I C bus to indicate that the LTC4310 is driving its SDA and SCL to the appropriate logic state. The isolation barrier can be pins with the logic state information it is receiving on its bridged by an inexpensive Ethernet (or other) transformer RXP and RXN pins from the other LTC4310. An LED at to achieve communications across voltage differences each READY pin indicates that READY is low. reaching thousands of volts, or it can be bridged by ca- DC1079A-A is populated with the LTC4310-1 and is in- pacitors for lower voltage isolation. DC1079A shows both 2 tended for use in I C systems up to 100kHz. DC1079A-B transformer and capacitor techniques. Separate supplies 2 is populated with the LTC4310-2 which is intended for I C are connected on opposite sides of the isolation barrier. bus speeds from 100kHz to 400kHz. Rise time accelerators provide strong pull-up currents on Design files for this circuit board are available at SCL and SDA rising edges to meet rise time specifications DEMO MANUAL DC1079A-A/DC1079A-B PERFORMANCE SUMMARY Table 1. DC1079A Typical Setup and Performance Summary (T = 25C) A PARAMETER CONDITIONS MIN TYP MAX UNITS Supply and Bus Voltage VCC A to GND A, VCC B to GND B, VCC C to GND C, VCC D to GND D 3 5.5 V Isolation GND A to GND B, 100V Capacitor Coupling 100 V GND C to GND D, EPF8119S Transformer Coupling 1500 V RMS 2 Maximum I C Clock DC1079A-A, LTC4310-1 100 kHz DC1079A-B, LTC4310-2 400 kHz Bus Pull-Up Resistors DC1079A-A, LTC4310-1 10 k DC1079A-B, LTC4310-2 3.3 k QUICK START PROCEDURE Demonstration circuit 1079A is easy to set up to evaluate 1500V Isolation with Transformer Coupling (Figure 3): RMS the performance of the LTC4310. Refer to Figure 2 and 1. Connect first supply (3V to 5.5V) across VCC C and Figure 3 for proper measurement equipment setup and GND C. follow the procedures below. 2 2. Connect first I C bus to SDA C and SCL C. 100V Isolation with Capacitor Coupling (Figure 2): 3. Set ENABLE C Jumper to EN. 1. Connect first supply (3V to 5.5V) across VCC A and 4. Connect second supply (3V to 5.5V) across VCC D GND A. and GND D. 2 2. Connect first I C bus to SDA A and SCL A. 2 5. Connect second I C bus to SDA D and SCL D. 3. Set ENABLE A Jumper to EN. 6. Set ENABLE D Jumper to EN. 4. Connect second supply (3V to 5.5V) across VCC B and GND B. 2 5. Connect second I C bus to SDA B and SCL B. 6. Set ENABLE B Jumper to EN. dc1079af 2