- Optical Isolation Amplifiers for Voltage Sensing
Aug 2012Broadcom Ltd.
BÖBLINGEN, Germany, Aug. 8, 2012 — Avago Technologies GmbH has announced the availability of a line of optically isolated voltage sensors. The optical isolation amplifiers are based on sigma-delta modulation that is 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 negative temperature coefficient thermistor isolation in insulated gate bipolar transistor modules, the ACPL-C87B, C87A and C870 provide designers with a 2-V input range and 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 servo and motor drives, the ACPL-C87B (±0.5% gain tolerance) can be used. The voltage sensors feature a 1-V/V unity gain with gain drift of −35 ppm/°C, and nonlinearity is kept to within 0.1% maximum. The voltage sensors include a shutdown pin that reduces the IDD1 current to only 15 mA during standby, which makes the sensors suited for battery-powered applications.
The optical isolation amplifiers use advanced sigma-delta modulation technology and chopper-stabilized amplifiers to provide accurate, safe and reliable current and voltage sensing. Differential outputs provide good isolation-mode noise rejection, low offsets, high gain accuracy and stability, and a signal bandwidth of 100 kHz.
The built-in reinforced safety insulation and high common mode rejection performance prevent erroneous voltage measurements and ensure reliable operation in noisy environments. The sensors have 15-kV/µs common-mode transient immunity and are housed in stretched eight-lead SO-8 plastic packages with 8-mm creepage and clearance that meet worldwide regulatory safety standards. Operating temperature ranges from −40 to 105 °C
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