The HCPL-7840 isolation amplifi er family was designedfor current sensing in electronic motor drives. In a typicalimplementation, motor currents fl ow through an externalresistor and the resulting analog voltage drop is sensed bythe HCPL-7840. A diff erential output voltage is created onthe other side of the HCPL-7840 optical isolation barrier.This diff erential output voltage is proportional to themotor current and can be converted to a single-endedsignal by using an op-amp as shown in the recommendedapplication circuit. Since common-mode voltage swingsof several hundred volts in tens of nanoseconds arecommon in modern switching inverter motor drives, theHCPL-7840 was designed to ignore very high commonmodetransient slew rates (of at least 10 kV/µs).The high CMR capability of the HCPL-7840 isolationamplifi er provides the precision and stability needed toaccurately monitor motor current in high noise motorcontrol environ-ments, providing for smoother control(less “torque ripple”) in various types of motor controlapplications.The product can also be used for general analog signalisolation applications requiring high accuracy, stability,and linearity under similarly severe noise con-ditions. Forgeneral applications, we recommend the HCPL-7840 (gaintolerance of ± 5%). The HCPL-7840 utilizes sigma delta(∑-Δ) analog-to-digital converter technology, chopperstabilized amplifi ers, and a fully diff erential circuit topologyfabricated using Avago’s 0.8 µm CMOS IC process.Together, these features deliver unequaled isolationmodenoise rejection, as well as excellent off set and gainaccuracy and stability over time and temperature. Thisperformance is delivered in a compact, auto-insertable,industry standard 8-pin DIP package that meets worldwideregulatory safety standards. (A gull-wing surfacemount option #300 is also available).
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
Worldwide safety approval:
UL 1577 (3750 Vrms/1 min.) and CSA, IEC/EN/DIN EN 60747-5-2