AOD421 MOSFET P-Channel 20V 12.5A TO-252 Equivalent & Substitute Parts

Part Overview

The AOD421 is a P-Channel MOSFET manufactured by Alpha & Omega Semiconductor Inc., designed for surface mount applications in the TO-252 (DPAK) package. This device operates at 20V drain-to-source voltage with a continuous drain current rating of 12.5A at 25°C ambient temperature. The AOD421 is classified as obsolete, necessitating identification of functionally equivalent substitute components for ongoing design support and production continuity.

Substiute Parts

AOD421

Alpha & Omega Semiconductor Inc.In Stock: 1887AOD421 Datasheet

Current PartRFQ

AOD403

Alpha & Omega Semiconductor Inc.In Stock: 200135AOD403 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AOD421 is determined by electrical and mechanical compatibility within the P-Channel MOSFET category. The primary substitution criteria are:

Electrical Compatibility Requirements:

• FET Type: P-Channel topology must be maintained
• Drain-to-Source Voltage (Vdss): Substitute must equal or exceed 20V
• Continuous Drain Current (Id): Substitute must equal or exceed 12.5A at 25°C ambient
• On-State Resistance (Rds On): Substitute must not exceed the original specification to maintain circuit performance
• Gate Threshold Voltage (Vgs(th)): Must be compatible with existing gate drive circuitry
• Operating Temperature Range: Must support -55°C to 175°C minimum

Mechanical Compatibility Requirements:

• Package Type: TO-252 (DPAK) surface mount package required
• Pin Configuration: 2 Leads + Tab (SC-63) configuration

The AOD403 qualifies as a substitute based on these criteria. It maintains P-Channel topology, exceeds voltage and current ratings, operates within the required temperature range, and uses the identical TO-252 (DPAK) package footprint.

Parameter Comparison

Engineering Selection Recommendations

AOD403 as Primary Substitute:

The AOD403 is the manufacturer-recommended substitute for the obsolete AOD421. Both devices are manufactured by Alpha & Omega Semiconductor Inc. and share identical TO-252 (DPAK) package geometry, enabling direct footprint compatibility.

The AOD403 provides superior electrical performance across all critical parameters:

• Vdss rating of 30V exceeds the 20V requirement, providing additional voltage margin
• Continuous drain current of 15A (Ta) exceeds the 12.5A specification
• On-state resistance of 6 mOhm (at 20A, 20V) is significantly lower than the AOD421's 75 mOhm, reducing power dissipation
• Operating temperature range matches the AOD421 specification (-55°C to 175°C)
• Moisture sensitivity level remains at MSL 1 (Unlimited)

Product Status Considerations:

The AOD421 is classified as obsolete, making continued sourcing impractical. The AOD403 is classified as "Not For New Designs," indicating limited availability but continued support for existing applications. For new designs, consultation with Alpha & Omega Semiconductor Inc. is necessary to identify current-generation alternatives.

Compliance Status:

The AOD403 carries RoHS3 compliance certification, whereas the AOD421 compliance status is not specified. Both devices are REACH Unaffected and classified under ECCN EAR99 for export control purposes.

Frequently Asked Questions (FAQ)

Q: Can the AOD403 directly replace the AOD421 in existing PCB designs?

A: Yes. Both devices use the TO-252 (DPAK) package with identical pin configuration (2 Leads + Tab, SC-63). The AOD403 is a direct footprint replacement. However, circuit simulation or testing is recommended to verify performance under specific application conditions due to differences in gate threshold voltage and input capacitance.

Q: What are the key electrical differences between AOD421 and AOD403?

A: The AOD403 has higher voltage rating (30V vs. 20V), higher current rating (15A vs. 12.5A), significantly lower on-state resistance (6 mOhm vs. 75 mOhm), higher gate threshold voltage (3.5V vs. 1.4V), and higher input capacitance (5300 pF vs. 620 pF). These differences may affect gate drive requirements and switching characteristics.

Q: Is the AOD403 suitable for applications originally designed for the AOD421?

A: The AOD403 meets or exceeds all electrical specifications of the AOD421, making it suitable for direct substitution in applications operating within the original design parameters. The higher ratings provide additional design margin.

Q: What is the significance of the higher gate threshold voltage in the AOD403?

A: The AOD403 has a gate threshold voltage of 3.5V compared to the AOD421's 1.4V. This requires higher gate drive voltage to achieve full on-state conduction. Existing gate drive circuits must be verified to supply sufficient voltage to the AOD403 gate terminal.

Q: Are there differences in switching speed between these devices?

A: Gate charge (Qg) differs significantly: AOD421 has 4.6 nC at 4.5V, while AOD403 has 120 nC at 10V. Higher gate charge indicates slower switching speed. Applications sensitive to switching frequency or EMI characteristics should evaluate this parameter.

Q: What is the moisture sensitivity level for both devices?

A: Both the AOD421 and AOD403 are rated MSL 1 (Unlimited), indicating no moisture sensitivity restrictions for storage or handling.

Q: Are both devices RoHS compliant?

A: The AOD403 is RoHS3 compliant. The AOD421 RoHS compliance status is not specified in the available data.