Demonstration circuit 2754A extends an I²C based QuikEval^™ interface to up to 450 feet and features the LTC4331. In order to realize the QuikEval interface, this demo circuit includes two complete I²C extenders and a remote side power supply formed from an LT3461 boost converter and two LT1761 LDOs.

The LTC4331 is a SMBus compatible I²C slave device extender designed for operation in high noise industrial environments. The I²C/SMBus is extended over a single twisted pair by a ±60V fault protected differential transceiver. The LTC4331’s extended 15V common mode voltage range allows it to bridge across different ground potentials.

When used as a QuikEval extender, the DC2754A requires the use of the DC2026 USB serial adapter. The DC2754A is NOT compatible with the DC590 USB serial adapter because the DC590 does not support clock stretching.

The DC2754A’s jumpers and turrets allow easy re-configuration for use in other applications and/or demonstrating other application circuits. The circuit board is fabricated with a score between the local and remote sides to allow physical separation. The link cable connections are made using either pluggable terminal blocks or an Ethernet cable.

Two complete I²C extenders are present. The first extender has a full set of diagnostic LEDs, jumpers, turrets and large (0805) resistors for simple user reconfiguration and connection for customer specific application(s). The second extender is configured specifically for the QuikEval EEPROM with no LEDs; however, it may be reconfigured and used for customer specific application(s) via 0603 jumpers and resistors and unpopulated test points on 0.1" centers.

The LTC4331 data sheet gives a complete description of the part, its operation and application information. The data sheet should be referred to when reading this demo manual. The LTC4331 is available in a 20-lead QFN package and three temperature grades (commercial 0°C to 70°C, industrial –40°C to 85°C, and high temperature –40°C to 125°C).