This reference design is intended for use in molded case circuit breakers (MCCB) electronic trip units. The programmable gain amplifier based design acts as the current monitoring for over-current earth fault relays. Utilizing a zero drift programmable amplifier, this design provides a ±10 % pick-up (A) accuracy and time delay (s) accuracy of 0 to -20%. Additionally, this solution was designed to handle harsh environment conditions by including features such as ambient insensitivity from -10 to 70 ⁰C and high electromagnetic immunity. Finally the analog front end of this design interfaces seemlessly with the TI MSP430 MCU for quicker evaluation and faster time-to-market.
Features
- Architecture enables the customer to easily create multiple circuit breaker models with different current ranges
- Using programmable gain control, fault current sensing range can be increased to > 10 times Ir and < 0.2 times Ir
- Lower total manufacturing cost with reduced component count and less calibration time vs. discrete opamp based electromechanical solution
- Robust design with ambient insensitivity from -10 to +70°C and better trip time repeatability vs. discrete opamp based electromechanical solution
- Wide input DC-DC converter with under voltage and overcurrent protection
- Self-power (CT powered) supply with reduced CT loading and lower power loss