AO4821 Equivalent & Substitute Parts

Part Overview

The AO4821 is a dual P-channel MOSFET array manufactured by Alpha & Omega Semiconductor Inc., designed for surface mount applications in 8-SOIC packaging. This component features a 12V drain-to-source voltage rating with 9A continuous drain current capability and 2W maximum power dissipation. The AO4821 is classified as obsolete, necessitating identification of functionally equivalent alternatives for ongoing design support and procurement requirements. Substitute parts must maintain compatibility across electrical specifications, thermal characteristics, and physical packaging to ensure direct replacement capability.

Substiute Parts

AO4821

Alpha & Omega Semiconductor Inc.In Stock: 10597AO4821 Datasheet

Current PartRFQ

IRF7324TRPBF

Infineon TechnologiesIn Stock: 33394IRF7324TRPBF Datasheet

MFR RecommendedRFQ

IRF7329TRPBF

Infineon TechnologiesIn Stock: 17541IRF7329TRPBF Datasheet

MFR RecommendedRFQ

SI4931DY-T1-GE3

Vishay SiliconixIn Stock: 8002SI4931DY-T1-GE3 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the AO4821 is determined by the following critical parameters:

Primary Compatibility Criteria:

• Configuration: 2 P-Channel (Dual) MOSFET array
• Package / Case: 8-SOIC (0.154", 3.90mm Width) surface mount
• Mounting Type: Surface Mount
• FET Feature: Logic Level Gate
• Operating Temperature Range: -55°C ~ 150°C (TJ)

Electrical Performance Criteria:

• Drain to Source Voltage (Vdss): Equal to or greater than 12V
• Current - Continuous Drain (Id) @ 25°C: Equal to or greater than 9A
• Power - Max: Equal to or greater than 2W
• Rds On (Max) @ Id, Vgs: Equal to or less than 19mOhm @ 9A, 4.5V
• Vgs(th) (Max) @ Id: Within acceptable threshold range
• Gate Charge (Qg) (Max) @ Vgs: Acceptable for switching performance

All three substitute parts meet the primary compatibility criteria. The IRF7329TRPBF and IRF7324TRPBF are direct electrical equivalents with enhanced specifications. The SI4931DY-T1-GE3 operates within the same voltage and temperature envelope but with reduced current rating and power dissipation.

Parameter Comparison

Engineering Selection Recommendations

IRF7329TRPBF (Infineon Technologies)

The IRF7329TRPBF is the primary recommended substitute for the AO4821. This part maintains identical 12V Vdss and 9A continuous drain current specifications while providing superior electrical performance with 17mOhm on-resistance compared to the original 19mOhm specification. The IRF7329TRPBF is classified as Active product status with ROHS3 compliance, ensuring long-term availability and regulatory alignment. The 8-SOIC package footprint is identical to the AO4821, enabling direct PCB replacement without layout modifications. Higher gate charge (57nC versus 23nC) requires evaluation in gate driver circuits operating at high switching frequencies.

IRF7324TRPBF (Infineon Technologies)

The IRF7324TRPBF provides an alternative with enhanced voltage rating (20V Vdss versus 12V), maintaining 9A continuous drain current and 18mOhm on-resistance. This part is suitable for applications where voltage margin above 12V is beneficial for reliability or design flexibility. Active product status and ROHS3 compliance support procurement continuity. The 8-SOIC package is compatible with existing PCB designs. Gate charge specification (63nC) is elevated relative to the original part.

SI4931DY-T1-GE3 (Vishay Siliconix)

The SI4931DY-T1-GE3 operates within the 12V voltage envelope with reduced continuous drain current rating (6.7A versus 9A) and lower maximum power dissipation (1.1W versus 2W). This substitute is applicable only to applications where the 6.7A current requirement is sufficient. Active product status and ROHS3 compliance are confirmed. The 8-SOIC package is mechanically compatible. This part is not suitable for designs requiring the full 9A current capability of the AO4821.

Frequently Asked Questions (FAQ)

Q: Can the IRF7329TRPBF directly replace the AO4821 without PCB modifications?

A: Yes. The IRF7329TRPBF is housed in the same 8-SOIC (0.154", 3.90mm Width) package with identical pin configuration. No PCB layout changes are required for mechanical and electrical connection. Gate driver circuits must accommodate the higher gate charge specification (57nC versus 23nC).

Q: What is the primary difference between the IRF7329TRPBF and IRF7324TRPBF?

A: The IRF7324TRPBF has a 20V Vdss rating compared to the IRF7329TRPBF's 12V rating. Both maintain 9A continuous drain current. The IRF7324TRPBF provides additional voltage margin for applications requiring higher transient voltage tolerance. Gate charge is higher on the IRF7324TRPBF (63nC versus 57nC).

Q: Is the SI4931DY-T1-GE3 suitable for all AO4821 applications?

A: No. The SI4931DY-T1-GE3 has a reduced continuous drain current rating of 6.7A compared to the AO4821's 9A specification. This part is suitable only for applications where the lower current rating meets design requirements. Maximum power dissipation is also reduced to 1.1W.

Q: What compliance certifications are available for substitute parts?

A: All three substitute parts are ROHS3 compliant and REACH unaffected. The AO4821 compliance status is not specified in available documentation.

Q: How does gate charge affect circuit performance?

A: Gate charge determines the energy required to switch the MOSFET on and off. The IRF7329TRPBF and IRF7324TRPBF have higher gate charge (57nC and 63nC respectively) compared to the AO4821 (23nC). Gate driver circuits must supply sufficient current to charge the gate within the required switching time. Higher gate charge may increase switching losses in high-frequency applications.

Q: Are all substitute parts available in the same packaging options?

A: All substitute parts are available in 8-SOIC surface mount packaging. The IRF7329TRPBF and IRF7324TRPBF are supplied in Cut Tape (CT) and Digi-Reel® packaging. The SI4931DY-T1-GE3 is supplied in Cut Tape (CT) and Digi-Reel® packaging. Packaging format does not affect electrical or mechanical compatibility.

Q: What is the operating temperature range for all parts?

A: All parts, including the AO4821 and all three substitutes, operate across the identical temperature range of -55°C to 150°C (junction temperature). Thermal performance differences are determined by power dissipation and package thermal resistance characteristics.