SI8921AD-AS4

Special Purpose Amplifiers Overview

The Skyworks SI8921AD-AS4 is an automotive-grade isolated analog amplifier featuring a differential input and differential output. It utilizes CMOS isolation technology to provide up to 5.0 kVrms withstand voltage per UL1577. The device supports a specified linear input range of ±62.5 mV with a nominal gain of 32.8x, resulting in a full-scale output of 2.05 V. Key electrical parameters include a typical signal delay of 0.8 µs, a bandwidth of 600 kHz, and a common-mode transient immunity of 75 kV/µs. It operates on supply voltages between 3.0 V and 5.5 V.

Special Purpose Amplifiers Feature Summary

• Automotive-grade qualification supporting AEC-Q100 standards and AIAG-compliant PPAP documentation.
• Galvanic isolation barrier utilizing proprietary CMOS technology for high reliability and low drift.
• Fail-safe output mode that activates upon loss of the primary-side supply voltage (VDDA).
• Differential analog output designed for direct interfacing with ADC inputs.

Special Purpose Amplifiers Applications

• Current shunt measurement in industrial inverters
• High-voltage motor control and drives
• Automotive onboard chargers and battery management systems

Special Purpose Amplifiers Procurement Notes

Verify the specific suffix 'AS4' indicates the wide-body SOIC-8 package configuration and reel packaging format. Confirm that the 'D' designation aligns with the required 5.0 kVrms insulation rating for your safety design. Ensure the component meets the Moisture Sensitivity Level 2A (MSL2A) requirements for your assembly process.

Special Purpose Amplifiers Selection Notes

Select this part when a differential output is required for noise rejection in high-speed sampling applications. The ±62.5 mV input range is suitable for low-resistance shunts where higher gain is necessary. Compare against the SI8921BD variant if a wider ±250 mV input range is preferred to reduce sensitivity to trace resistance errors.

Special Purpose Amplifiers Part Context

This component belongs to the Si8921/Si8922 family of galvanically isolated amplifiers. While the Si8922 provides a single-ended output, the Si8921 series specifically offers a differential output topology. The 'AD' designation identifies the specific input range and insulation class within this product line.

Special Purpose Amplifiers Replacement Considerations

SI8921BD-AS4

Special Purpose Amplifiers FAQ

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

When the high-voltage-side supply voltage (VDDA) is lost, the Si8921AD-AS4 enters a fail-safe mode with an output voltage nominally at -2.8 V.

How does the device handle common-mode transients?

The device features a typical common-mode transient immunity (CMTI) of 75 kV/µs, allowing it to maintain accuracy in high-power switching environments like motor drives.