Isolation amplifiers suit motor control and current sensing applications

Avago Technologies announces new precision optical isolation amplifiers for motor control and current sensing applications. The ACPL-790B, ACPL-790A, and ACPL-7900 devices improve the accuracy and response times of the Avago isolation amplifier portfolio, while addressing compact applications with a smaller footprint package design. The high-precision isolation amplifiers are suitable for current and voltage sensing in ac and brushless dc motor drives, industrial inverters, servo motor drives, wind power generation, solar panel power systems, and general analog isolation.

As current flows through the external resistor in a motor drive implementation, the resulting analog voltage drop is sensed by an ACPL-790B/790A/7900 isolation amplifier, and it allows a proportional output voltage to safely be created on the other side of the optical isolation barrier. Competing solutions based on Hall Effect technology and current transformer technology suffer electrical parameter variation over temperature fluctuations and require a larger footprint in a design.

The ACPL-790B precise isolation amplifier provides up to 0.5% high gain accuracy, and offer 200 kHz bandwidth and 1.6 usec fast response time to enable capture of transient signals in short circuit and overload conditions. The devices operate from a single 5-V supply that is compatible with 3.3-V outputs. This performance is delivered in a compact DIP-8 package that is suitable for automated assembly and meets worldwide regulatory safety standards.

Additional ACPL-790B/790A/7900 product features:

• High gain tolerance options: ±0.5% (ACPL-790B), ±1% (ACPL-790A), and ±3% (ACPL-7900)
• Extended temperature operation: -40° to 105° C
• Compliant to UL 1577 5000 Vrms/1 minute rating, IEC/EN/DIN EN 60747-5-5 and CSA industrial safety standards
• 15 kV/us common-mode transient immunity for less torque ripple in motor control applications
• Sigma-Delta analog-to-digital converter technology for accurate current measurement from different phases of motor
• 60 dB signal-to-noise ratio for stability needed in noisy motor control environments