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Electronics and Semiconductors

Isolated Current Sense Amplifier Targets Industrial Motor Drives and Inverters

02 September 2015

The Si8920 is an isolated current sense amplifier that provides a current shunt measurement solution for power control systems operating in harsh environments. These systems include industrial motor drives, solar inverters, high-voltage power converters, uninterruptible power supplies (UPS) and electric/hybrid-electric vehicle (EV/HEV) systems.

Silicon Labs Si8920 Isolated Current Sense Amplifier. Source: Silicon LabsSilicon Labs Si8920 Isolated Current Sense Amplifier. Source: Silicon LabsFast, accurate current sensing is essential for all high-power systems and power converters with high-voltage stages. Measuring current on high-voltage rails (up to 1200 V) with a galvanically isolated amplifier provides critical information to the low-voltage controller for faster response time and efficiency. The Si8920 isolated amplifier provides a differential, low-voltage input scaled for connection to current shunt resistors, enabling the controller to measure current on high-voltage rails while maintaining electrical isolation. The device’s signal bandwidth of up to 750 kHz is designed to deliver precise DC current measurement and accurate representation of primary signal and harmonics.

The Si8920 isolated amplifier supports up to 5 kV withstand and 1200 V working voltage, and offers a wide operating temperature range, noise immunity and long lifetimes. Its1 µV/°C offset drift provides stable performance over diverse operating conditions.

Applications include industrial automation, green energy and Internet infrastructure equipment. The Si8920 isolated amplifier operates over a full industrial temperature range and is designed to support product lifetimes of up to 100 years.

It also provides a 0.75 µs signal delay across the isolation barrier, allowing power control systems to react rapidly to transient load conditions. Ultra-low signal delay enables control loops to respond quickly, resulting in an efficient and stable system. Low signal delay allows a power system to make quick corrective responses to unusual, potentially dangerous events, which helps reduce equipment repair and maintenance costs.

The Si8920 isolated amplifier is available now in standard SOIC and DIP packages. Si8920 pricing in 10,000-unit quantities begins at $2.39. The Si8920ISO-KIT evaluation kit enables developers to connect quickly to a shunt resistor to evaluate its analog isolation functionality including low-voltage differential input, response times, offset and gain characteristics. Priced at $29, the Si8920ISO-KIT is available now from Silicon Labs and authorized distributors.

To contact the author of this article, email engineering360editors@ihs.com

Related Links:

www.silabs.com/isolatedamplifier



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