DESCRIPTION
In a typical implementation, motor currents flow through an external resistor and the resulting analog voltage drop is sensed by the HCPL-7840. 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 amplifier 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 amplifiers, and a fully differential circuit topology fabricated using Avago’s 0.8 μm CMOS IC process.
Avago Technologies
