Description
The HCPL-7840 isolation amplifi er family was designed for current sensing in electronic motor drives. In a typical implementation, motor currents fl ow through an external resistor and the resulting analog voltage drop is sensed by the HCPL-7840.
A diff erential output voltage is created on the other side of the HCPL-7840 optical isolation barrier.This diff 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 commonmode transient slew rates (of at least 10 kV/μs).
The high CMR capability of the HCPL-7840 isolation amplifi er provides the precision and stability needed to accurately monitor motor current in high noise motor control environ-ments, providing for smoother control (less “torque ripple”) in various types of motor control applications.
The product can also be used for general analog signal isolation applications requiring high accuracy, stability, and linearity under similarly severe noise con-ditions. For general applications, we recommend the HCPL-7840 (gain tolerance of ± 5%). The HCPL-7840 utilizes sigma delta (∑-Δ) analog-to-digital converter technology, chopper stabilized amplifi ers, and a fully diff erential circuit topology fabricated using Avago’s 0.8 μm CMOS IC process. Together, these features deliver unequaled isolationmode noise rejection, as well as excellent off set and gain accuracy and stability over time and temperature. This performance is delivered in a compact, auto-insertable, industry standard 8-pin DIP package that meets worldwide regulatory safety standards. (A gull-wing surface mount option #300 is also available).
Features
? 15 kV/μs common-mode rejection at VCM = 1000 V
? Compact, auto-insertable standard 8-pin DIP package
? 0.00025 V/V/°C gain drift vs. temperature
? 0.3 mV input off set voltage
? 100 kHz bandwidth
? 0.004% nonlinearity
? Worldwide safety approval:UL 1577 (3750 Vrms/1 min.) and CSA, IEC/EN/DIN EN 60747-5-2
? Advanced Sigma-Delta (∑-Δ) A/D converter technology
? Fully diff erential circuit topology
? 0.8 μm CMOS IC technology
Applications
? Motor phase and rail current sensing
? Inverter current sensing
? Switched mode power supply signal isolation
? General purpose current sensing and monitoring
? General purpose analog signal isolation
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Important Notice
Performance figures, data and any illustrative material provided in this data sheet are typical and must be specifically confirmed in writing by F-tone Networks before they become applicable to any particular order or contract. In accordance with the F-tone Networks policy of continuous improvement specifications may change without notice.
The publication of information in this data sheet does not imply freedom from patent or other protective rights of F-tone Networks or others. Further details are available from any F-tone Networks sales representative.
