Si8921/22 Data Sheet
Isolated Amplifier for Current Shunt Measurement
KEY FEATURES The Si8921/22 is a galvanically isolated analog amplifier. The low-voltage differential input is
ideal for measuring voltage across a current shunt resistor or for any place where a sensor
must be isolated from the control system. The output is a differential analog signal amplified by
either 8.2x or 32.8x.
The very low signal delay of the Si8921/22 allows control systems to respond quickly to fault
conditions or changes in load. Low offset and gain drift ensure that accuracy is maintained over
the entire operating temperature range. Exceptionally high common-mode transient immunity
means that the Si8921/22 delivers accurate measurements even in the presence of high-power
switching as is found in motor drive systems and inverters.
The Si8921/22 isolated amplifier utilizes Silicon Labs’ proprietary isolation technology. It supports up to 5.0 kVrms withstand voltage per UL1577. This technology enables higher performance, reduced variation with temperature and age, tighter part-to-part matching, and longer lifetimes compared to other isolation technologies.
Applications:
• Industrial, HEV and renewable energy inverters
• AC, Brushless, and DC motor controls and drives
• Variable speed motor control in consumer white goods
• Isolated switch mode and UPS power supplies • Low voltage differential input
• ±62.5 mV and ±250 mV options
• Low signal delay: 0.8 µs
• Typical input offset: ±40 µV
• Typical gain error: ±0.1%
• Excellent drift specifications
• ±0.5 µV/°C typical offset drift …
