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Optically-isolated voltage sensors suit renewable energy systems

Optically-isolated voltage sensors suit renewable energy systems

Avago Technologies introduces a new family of optically-isolated voltage sensors, which are optical isolation amplifiers based on sigma-delta modulation that is specifically optimized for voltage sensing. Targeted for applications such as sensing voltages in electronic power conversion systems commonly found in motor drives, switching power supplies, and renewable energy systems, as well as sensor interfaces such as NTC thermistor isolation in IGBT modules, the ACPL-C87B, C87A, and C870 provide designers with a 2-V input range and high 1 GΩ input impedance.

For general applications, the ACPL-C87A (±1% gain tolerance) and the ACPL-C870 (±3% gain tolerance) are recommended. For high-precision applications such as renewable energy inverters where it is important to accurately track the fluctuating (due to changing sun conditions) dc bus voltage and for high-performance servo and motor drives, the ACPL-C87B (±0.5% gain tolerance) can be used. The voltage sensors features a 1V/V unity gain with low gain drift of -35ppm/˚C and non-linearity is kept to within 0.1% max. The voltage sensors include an active-high shutdown pin, which reduces the IDD1 current to only 15µA during standby, making the sensors well-suited for battery-powered and other power-sensitive applications.

Avago Technologies' Optical Isolation Amplifiers have been using advanced Sigma-Delta modulation technology and chopper-stabilized amplifiers to provide accurate, safe, and reliable current and voltage sensing for more than two decades in motor drives and power converters. Differential outputs on the new devices provide exceptional isolation-mode noise rejection, low offsets, high gain accuracy and stability, and a wide signal bandwidth of 100 kHz.

The built-in reinforced safety insulation and high CMR (common mode rejection) performance prevents erroneous voltage measurements and ensures reliable operation in a noisy environment. The optically-isolated voltage sensors have a 15 kV/µs common-mode transient immunity. Safety approvals include CSA and IEC/EN/DIN EN60747-5-5 with a VIORM of 1,230 Vpeak. Additionally, the sensors are UL recognized with 5,000 Vrms for 1 minute per UL1577.

The ACPL-C87x voltage sensors are housed in stretch 8-lead SO-8 plastic packages with 8-mm creepage and clearance that meet global regulatory safety standards. The sensors also have a wide operating temperature range of -40° to 105° C.

For more information, contact Avago Technologies, 350 W. Trimble Rd., San Jose, CA 95131. Phone: (800) 235-0312.

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