FDN372S N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The FDN372S is an N-Channel MOSFET manufactured by onsemi, rated for 30V drain-to-source voltage with 2.6A continuous drain current at 25°C. The device is housed in a SOT-23-3 surface mount package and is designed for general-purpose switching applications requiring moderate current handling in compact form factors.

The FDN372S carries an Obsolete product status. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications currently utilizing this component.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	30	V
Continuous Drain Current (Id) @ 25°C	2.6	A
On-Resistance (Rds On) @ Id, Vgs	40 mOhm @ 2.6A, 10V	mOhm
Gate Threshold Voltage (Vgs(th))	3	V @ 1mA
Gate Charge (Qg) @ Vgs	8.1	nC @ 5V
Power Dissipation (Max)	500	mW (Ta)
Operating Temperature Range	-55 to 150	°C (TJ)
Package Type	SOT-23-3	Surface Mount

Substitute Part Grouping Explanation

Substitution of the FDN372S is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

Drain-to-Source Voltage (Vdss) must equal or exceed 30V
Continuous Drain Current (Id) must meet or exceed 2.6A at 25°C
On-Resistance (Rds On) characteristics must support the application's switching and conduction losses
Gate Threshold Voltage (Vgs(th)) must be compatible with the drive circuit
Operating temperature range must encompass -55°C to 150°C (TJ)

Mechanical Compatibility Criteria:

Package type must be SOT-23-3 or equivalent surface mount form factor (TO-236-3, SC-59)
Mounting type must be Surface Mount
Pin configuration must be compatible with existing PCB layouts

Substitute parts are grouped into two categories based on current rating and thermal performance:

Category A (Higher Current Rating): Parts with Id ≥ 3.5A provide enhanced current handling and thermal margin beyond the FDN372S baseline.

Category B (Matched Current Rating): Parts with Id between 2.5A and 3.7A provide direct functional equivalence with minimal design impact.

Parameter Comparison

Parameter	FDN372S (Main)	AO3404A	PMV40UN2R	PMV45EN2R	RQ5E035BNTCL	RSR025N03TL	RTR040N03TL
Manufacturer	onsemi	UMW	Nexperia USA Inc.	Nexperia USA Inc.	Rohm Semiconductor	Rohm Semiconductor	Rohm Semiconductor
Vdss (V)	30	30	30	30	30	30	30
Id @ 25°C (A)	2.6	5.8	3.7	4.1	3.5	2.5	4.0
Rds On @ Id, Vgs (mOhm)	40 @ 2.6A, 10V	25 @ 5.8A, 10V	44 @ 3.7A, 4.5V	42 @ 4.1A, 10V	37 @ 3.5A, 10V	70 @ 2.5A, 10V	48 @ 4A, 4.5V
Vgs(th) (V)	3 @ 1mA	3 @ 250µA	0.9 @ 250µA	2 @ 250µA	2.5 @ 1mA	2.5 @ 1mA	1.5 @ 1mA
Qg @ Vgs (nC)	8.1 @ 5V	17 @ 10V	12 @ 4.5V	6.3 @ 10V	6 @ 10V	4.1 @ 5V	8.3 @ 4.5V
Power Dissipation (mW)	500	1400	490	510	1000	1000	1000
Operating Temp Range (°C)	-55 to 150	to 150	-55 to 150	-55 to 150	to 150	to 150	to 150
Package	SOT-23-3	SOT-23	TO-236AB	TO-236AB	TSMT3	TSMT3	TSMT3
Product Status	Obsolete	Active	Active	Active	Active	Not For New Designs	Active
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitute Recommendations:

PMV45EN2R (Nexperia USA Inc.) is the preferred substitute for the FDN372S. This part maintains electrical compatibility with 30V Vdss and 4.1A Id rating, exceeding the FDN372S baseline current requirement. The device is Active status with ROHS3 compliance and full operating temperature range support (-55°C to 150°C). The TO-236AB package is mechanically compatible with SOT-23-3 footprints. Power dissipation of 510mW closely matches the FDN372S specification.

PMV40UN2R (Nexperia USA Inc.) provides an alternative with 3.7A Id rating and 490mW power dissipation, offering near-identical thermal characteristics to the FDN372S. Active product status and ROHS3 compliance ensure long-term availability and regulatory compliance.

RTR040N03TL (Rohm Semiconductor) offers 4A Id rating with 1W power dissipation capability. Active product status and ROHS3 compliance support production continuity. The TSMT3 package requires PCB layout verification for mechanical compatibility.

Secondary Substitute Recommendations:

RQ5E035BNTCL (Rohm Semiconductor) provides 3.5A Id rating with 1W power dissipation. Active product status and ROHS3 compliance are confirmed. TSMT3 package requires footprint verification.

AO3404A (UMW) offers the highest current rating at 5.8A with 1.4W power dissipation, providing significant thermal and current margin. Active product status and ROHS3 compliance are confirmed. This part is suitable for applications requiring enhanced performance headroom.

Not Recommended:

RSR025N03TL (Rohm Semiconductor) carries a "Not For New Designs" product status and is not recommended for new applications or long-term production commitments.

Frequently Asked Questions (FAQ)

Q: Can the FDN372S be directly replaced with any of these substitute parts without PCB modification?

A: PMV45EN2R and PMV40UN2R use TO-236AB packaging, which is mechanically compatible with SOT-23-3 footprints and require no PCB layout changes. RQ5E035BNTCL, RSR025N03TL, and RTR040N03TL use TSMT3 packaging (SC-96), which has a different footprint and requires PCB layout verification before implementation.

Q: What is the primary difference between the substitute parts?

A: The substitute parts differ primarily in continuous drain current rating (2.5A to 5.8A), on-resistance characteristics, and power dissipation capability. Parts with higher Id ratings provide greater thermal margin and current handling capacity. Package type also varies between SOT-23 variants and TSMT3.

Q: Are all substitute parts RoHS compliant?

A: All recommended substitute parts carry ROHS3 compliance certification. The FDN372S RoHS status is not specified in the available documentation.

Q: Which substitute part has the lowest on-resistance?

A: AO3404A exhibits the lowest on-resistance at 25 mOhm (@ 5.8A, 10V), providing superior conduction efficiency compared to the FDN372S baseline of 40 mOhm.

Q: Can I use a substitute part with higher current rating in place of the FDN372S?

A: Yes. Parts with higher Id ratings (such as AO3404A at 5.8A or RTR040N03TL at 4A) are electrically compatible and provide enhanced performance margin. Verify that the application circuit can accommodate the different gate charge and threshold voltage characteristics of the selected substitute.

Q: What is the impact of different gate threshold voltages on circuit operation?

A: Gate threshold voltage (Vgs(th)) affects the gate drive voltage required for device turn-on. The FDN372S specifies 3V @ 1mA. Substitute parts range from 0.9V to 3V. Lower threshold voltages enable operation with reduced gate drive voltage, while higher values require stronger drive signals. Verify compatibility with the existing gate drive circuit before substitution.

Q: Are TSMT3 package parts suitable for high-volume production?

A: TSMT3 packaged parts (RQ5E035BNTCL, RSR025N03TL, RTR040N03TL) are suitable for high-volume production. However, PCB layout and assembly process parameters must be verified and qualified before implementation, as the package footprint differs from SOT-23-3.

Q: What is the significance of product status in selecting a substitute?

A: Product status indicates long-term availability and manufacturer support. Active status parts (AO3404A, PMV40UN2R, PMV45EN2R, RQ5E035BNTCL, RTR040N03TL) are recommended for new designs and ongoing production. RSR025N03TL carries "Not For New Designs" status and should be avoided for new applications.

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