SI8921AB-ASR

Special Purpose Amplifiers Overview

The Skyworks SI8921AB-ASR is an automotive-grade isolated analog amplifier designed for current shunt measurement. It features a specified linear differential input range of ±62.5 mV and provides a differential output amplified by a gain of 32.8x. The device utilizes CMOS isolation technology to support up to 5.0 kVRMS withstand voltage per UL1577. Key electrical characteristics include a typical signal delay of 0.8 µs, a bandwidth of approximately 600 kHz, and a common-mode transient immunity of 75 kV/µs. It operates within a temperature range of –40 °C to +125 °C.

Special Purpose Amplifiers Feature Summary

• Automotive-grade qualification with AEC-Q100 certification and AIAG-compliant PPAP documentation support.
• Galvanic isolation barrier supporting high common-mode transient immunity for accurate measurements in noisy environments.
• Low-voltage differential input optimized for direct connection to low-resistance current shunt resistors.
• Fail-safe output mode that activates upon loss of the primary-side supply voltage.

Special Purpose Amplifiers Applications

• Automotive onboard chargers
• Battery management systems
• Charging stations

Special Purpose Amplifiers Procurement Notes

Verify the specific ordering suffix -ASR corresponds to the narrow body SOIC package and reel packaging configuration required for your assembly process. Confirm that the automotive grade designation aligns with your project's quality requirements and that the component meets all necessary safety regulatory approvals for your target market.

Special Purpose Amplifiers Selection Notes

Select this part when a differential output is required for driving ADCs or other differential inputs. The ±62.5 mV input range is suitable for applications requiring high sensitivity across small shunt voltages. Ensure the PCB layout supports the narrow body SOIC footprint and maintains adequate creepage and clearance distances as defined by the safety certifications.

Special Purpose Amplifiers Part Context

This component belongs to the Si8921/Si8922 family of isolated amplifiers from Skyworks Solutions. The Si8921 variant specifically provides a differential output, whereas the Si8922 offers a single-ended output. Both share similar isolation technologies and performance metrics but differ in output topology and pin configurations.

Special Purpose Amplifiers Replacement Considerations

Check for other variants within the Si8921 series, such as the Si8921BB (±250 mV input range) or non-automotive grades like the Si8921AD-IS4, depending on input range and qualification needs.

Special Purpose Amplifiers FAQ

What is the fail-safe output voltage when VDDA is removed?

When the high-voltage-side supply voltage (VDDA) is removed, the Si8921AB-ASR enters a fail-safe mode with an output voltage nominally at –2.8 V.

How does the device handle common-mode noise?

The device features high common-mode transient immunity of 75 kV/µs, allowing it to reject large noise transients present on the high-voltage side during switching operations.