HCPL-7800A-000E

The HCPL-7800(A) isolation amplifier family was 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 HCPL-7800(A). A differential output voltage is created on the other side of the HCPL-7800(A) optical isolation barrier. This differential 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 commonmode voltage swings of several hundred volts in tens of nanoseconds are common in modern switching inverter motor drives, the HCPL-7800(A) was designed to ignore very high common-mode transient slew rates (of at least 10 kV/µs).

The high CMR capability of the HCPL-7800(A) 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-7800 (gain tolerance of ±3%). For precision applications Avago Technologies offers the HCPL-7800A with part-to-part gain tolerance of ±1%. The HCPL-7800(A) utilizes sigma delta (Σ−∆) analog-to-digital converter technology, chopper stabilized amplifiers, and a fully differential circuit topology.