Isolation Amplifier

The HCPL-7800 isolation amplifier family was designed to sense current in electronic motor drives. In typical automotive and industrial applications, motor currents flow through an external resistor and the resulting analog voltage drop is sensed by the HCPL-7800. The HCPL-7800 isolation amplifier family is based on Avago's optocoupler and optoelectronic technology.

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

The high CMR capability of the HCPL-7800 isolation amplifier provides the precision and stability needed to accurately monitor motor current in high noise motor control environments, 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 conditions. For general applications, we recommend the HCPL-7800 (gain tolerance of /- 3%). The HCPL-7800 utilizes sigma delta (S-D) analog-to-digital converter technology, chopper stabilized amplifiers, and a fully differential circuit topology.

Together, these features deliver unequaled isolation-mode noise rejection, as well as excellent offset 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).