Avago Technologies Launches Three Precision Isolation Amplifiers for Industrial Motor Control and Renewable Energy Markets

Based on sigma-delta analog-to-digital converters and chopper stabilized amplifiers, the new isolation amplifiers feature high gain accuracy, low temperature drift, 3.3 V/5 V output supply operation and a wide -40 to +105°C operating temperature range. These features are delivered in a stretched SO-8 package that has a footprint 30% smaller than the standard DIP-8 package. When mounted on a PCB, it occupies a space that is a fraction of that for a traditional Hall Effect or transformer based isolation amplifier.

The series is implemented with a fully differential circuit topology with a gain accuracy of ±0.5% (ACPL-C79B), ±1% (ACPL-C79A), and ±3% (ACPL-C790). Normalized gain drift is ‑50 ppm/°C. With a 200 kHz bandwidth and 1.6 µs response time, the ACPL-C79x captures transients during short circuit and overload conditions. Operating from a single 5 V supply, the isolation amplifier series features an excellent nonlinearity of 0.05% and a SNR of 60 dB.

The ACPL-C79x high common-mode transient immunity of 15 kV/µs provides the precision and stability needed to accurately monitor current in high noise motor control environments. This ensures smoother control with less “torque ripple” in many motor control applications.

Pending safety and regulatory approvals include:

– IEC/EN/DIN EN 60747-5-5: 1140 Vpeak working insulation voltage

– UL 1577: 5000 Vrms/1 minute double protection rating

– CSA: Component Acceptance Notice #5

Isolation Amplifier Applications and Markets

Widely used for motor phase and rail current sensing, servo motor drive, switching power supply feedback isolation, DC link voltage monitoring, inverter current sensing and switching power supply feedback isolation, the ACPL-C97x targets industrial automation and instrumentation, renewable energy, and HVAC markets.

In a typical motor drive application, currents through a small value current sense resistor cause a voltage drop that is sensed by the ACPL-C79x isolation amplifier and a differential output voltage, proportional to the current, is created on the output side of the isolation barrier.

Key Features

- High gain tolerance options: ±0.5% (ACPL-C79B), ±1% (ACPL-C79A), and ±3% (ACPL-C790)

- High Signal-to-Noise ratio: 60 dB

- Excellent linearity: 0.05%

- Low input offset voltage and drift: 0.6 mV and 3µV/° C

- Low gain change vs. temperature: -50 ppm/°C

- High bandwidth: 200 kHz typical, 140 kHz minimum

- 3.3 V compatible outputs

- 15 kV/µs common-mode transient immunity at Vcm =1500 V

- Fast response time: 1.6 µs

- Advanced Sigma-Delta Analog-to-Digital converter and full differential isolation

- Safety and regulatory approval (pending)

o IEC/EN/DIN EN 60747-5-5: 1140 Vpeak working insulation voltage

o UL 1577: 5000 Vrms/1 minute double protection rating

o CSA: Component Acceptance Notice #5

- 0.5 mm internal package distance-through-insulation (DTI)

- 8 mm minimum package creepage and clearance

- Wide supply voltage: 3 V to 5.5 V

- Compact 8-pin stretched SO-8 package: 30% smaller than DIP-8 package

- Extended temperature operation: -40° C to 105° C

Packaging and Temperature Range
The ACPL-C79x isolation amplifiers are available in a compact 8-pin stretched SO-8 package for automatic SMT assembly and are RoHS compliant. All devices operate over a very wide temperature range, -40 ° C to +105° C.

In order to achieve high insulation ratings, package creepage and clearance is 8 mm and distance-through-isolation, DTI, is 0.5 mm.