Avago Technologies’ New ACPL-C797 Sigma-Delta ADC Increase Accuracy and Isolation

The ACPL-C797 is a significant upgrade compared to Avago’s successful first generation HCPL-7860 current sense amplifier. Upgraded features and specifications include a -40 to +105° C operating temperature range, both 5 and 3.3 V compatible digital outputs, lower offset voltage, a gain accuracy of ±1%, and a ±10% accurate clock frequency. By implementing a digital filter in an FPGA, ASIC or DSP, the serial output is decoded to 12-bit effective resolution. In addition, the new isolation amplifier features 78 dB signal-to-noise ratio and minimizes EMI with a slew rate controlled output.

Available in a new Stretched SO-8 (SSO-8) package, the ACPL-C797 printed circuit board footprint is 30% smaller than the traditional DIP-8. Even with the miniature package, the ACPL-C797 meets 8 mm clearance and creepage requirements and satisfies 1140 Vpeak working insulation voltage and 5 kVrms/minute isolation voltage safety requirements per IEC/EN/DIN EN 60747-5-5, UL 1577 and CSA standards.

The ACPL-C797 also meets the 0.5 mm distance through isolation (DTI) specification that is required for many medical applications. The SSO-8 package can be used with automatic assembly equipment, unlike many Hall Effect current transducers that require manual insertion in assembly.

Applications for the ACPL-C797 center around current and voltage sensing in power conversion and motor drive systems, such as in AC and DC brushless motor drives, industrial power inverters, servo motor drives, robotics, wind power generation and solar panel power systems. Other applications include switching power supply signal isolation, industrial A/D conversion and general purpose isolated sensing.

ACPL-C797 Isolation Amplifier Key Features

• ±1% maximum gain error
• High resolution: 12-bit effective number of bits
• -40 to 105° C operating temperature range
• 3.3 and 5 V compatible outputs
• Slew rate controlled outputs for low EMI generation
• Reinforced optical isolation and worldwide safety approval
– 5 kVrms/1 minute isolation voltage per UL 1577
– 1140 Vpk working insulation voltage per IEC/EN/DIN EN 60747-5-5 and CSA
• 0.5 mm distance through insulation (DTI) specification meets medical application requirements
• Compact, auto-insertable stretched SO-8 package
– 30% smaller footprint than an 8-pin DIP