Avago ACPL-785J绝缘放大器应用方案

Avago 公司的ACPL-785J是绝缘放大器,主要为马达驱动的电流检测而设计. ACPL-785J的输出电压直接和ADC兼容,3us快速短路检测,温度失调为1uV/度V,具有25kV/us的绝缘瞬态防卫度,工作温度-40度到85度C.主要应用在逆变器电流检测,开关电源信号隔离,工业用ADC,马达相电流和轨电流检测等.本文介绍了ACPL-785J的主要特性,内部方框图, 低成本三相电流检测电路图和应用电路, 电源和检测电阻连接图.

ACPL-785J Isolation Amplifier with Short Circuit and Overload Detection
The ACPL-785J isolation amplifier is designed for current sensing in electronic motor drives. In a typical implementation, motor currents flow through an external resistor and the resulting analog voltage drop is sensed by the ACPL-785J. A larger analog output voltage is created on the other side of the ACPL-785J’s optical isolation barrier. The output voltage is proportional to the motor current and can be connected directly to a single-supply A/D converter. A digital over-range output (/FAULT) and an analog rectified output (ABSVAL) are also provided.

The wire OR-able over-range output (/FAULT) is useful for quick detection of short circuit conditions on any of the motor phases. The wire-OR-able rectified output (ABSVAL), simplifies measure-ment of motor load since it performs polyphase rectification. Since the common-mode voltage swings several hundred volts in tens of nanoseconds in modern electronic motor drives, the ACPL-785J was designed to ignore very high common-mode transient slew rates (10 kV/μs).

±3% gain tolerance part (HCPL-788J) is also available
ACPL-785J主要特性:
Output Voltage Directly Compatible with A/D Converters (0 V to VREF)
Fast (3 μs) Short Circuit Detection with Transient Fault Rejection
Absolute Value Signal Output for Overload Detection
1 μV/°C Offset Change vs. Temperature
SO-16 Package
–40°C to +85°C Operating Temperature Range
25 kV/μs Isolation Transient Immunity
Regulatory Approvals: UL, CSA, IEC/EN/DIN EN 60747-5-5 (891 Vpeak Working Voltage)
Options:
ACPL-785J-000E
ACPL-785J-060E
ACPL-785J-500E
ACPL-785J-560E
ACPL-785J应用:
Inverter Current Sensing
Switching Power Supply Signal Isolation
Industrial A/D Converter
Motor Phase and Rail Current Sensing
General Purpose Current Sensing and Monitoring
ACPL-785J优势:
High common-mode rejection 25 kV/µs at VCM = 1000 V provides precision and stability in high noise motor control environments
±5% gain tolerance provides accurate measurement in highly noisy motor control environments
Advanced sigma-delta A/D converter technology ensures high precision
Wide operating temperature range
Integrated over-current and overload detection simplifies design




图1.ACPL-785J内部方框图



图2.ACPL-785J低成本三相电流检测电路图(带短路保护和过载检测)




图3.ACPL-785J推荐应用电路




图4.ACPL-785J推荐电源和检测电阻连接图