Description
The HCPL-7840 isolation amplifer family was designed for current sensing in electronic motor drives. In a typical implementation, motor currents ï¬ow through an external resistor and the resulting analog voltage drop is sensed by the HCPL-7840. A diï¬erential output voltage is created on the other side of the HCPL-7840 optical isolation barrier. This diï¬erential output voltage is proportional to the motor current and can be converted to a single-ended signal by using an op-amp as shown in the recommended application circuit. Since common-mode voltage swings of several hundred volts in tens of nanoseconds are common in modern switching inverter motor drives, the HCPL-7840 was designed to ignore very high common mode transient slew rates (of at least 10 kV/μs).
The high CMR capability of the HCPL-7840 isolation amplifer provides the precision and stability needed to accurately monitor motor current in high noise motor control environ-ments, providing for smoother control (less âtorque rippleâ) in various types of motor control applications.
Features
â 15 kV/μs common-mode rejection at VCM = 1000 V
â Compact, auto-insertable standard 8-pin DIP package
â 0.00025 V/V/°C gain drift vs. temperature
â 0.3 mV input oï¬set voltage
â 100 kHz bandwidth
â 0.004% nonlinearity
â Worldwide safety approval:
UL 1577 (3750 Vrms/1 min.)
and CSA, IEC/EN/DIN EN 60747-5-2
â Advanced Sigma-Delta (â-Î) A/D converter technology
â Fully diï¬erential circuit topology
â 0.8 μm CMOS IC technology
Applications
â Motor phase and rail current sensing
â Inverter current sensing
â Switched mode power supply signal isolation
â General purpose current sensing and monitoring
â General purpose analog signal isolation
|