FDS4953 Equivalent & Substitute Parts

Part Overview

The FDS4953 is a dual P-channel MOSFET array manufactured by onsemi, designed for surface mount applications in the 8-SOIC package. This device features a 30V drain-to-source voltage rating with 5A continuous drain current capability and 900mW maximum power dissipation. The FDS4953 operates across an extended temperature range of -55°C to 175°C and incorporates logic level gate drive characteristics suitable for low-voltage switching applications.

The FDS4953 is classified as an obsolete product. Identifying equivalent and substitute parts is necessary to support ongoing maintenance, repair, and redesign efforts for legacy systems utilizing this component. Substitute parts must maintain compatibility across critical electrical parameters including voltage rating, current capacity, package configuration, and thermal characteristics.

Key Parameters

Parameter	FDS4953 Value	Unit
Drain to Source Voltage (Vdss)	30	V
Current - Continuous Drain (Id) @ 25°C	5	A
Rds On (Max) @ Id, Vgs	55 @ 5A, 10V	mOhm
Vgs(th) (Max) @ Id	3 @ 250µA	V
Gate Charge (Qg) (Max) @ Vgs	9 @ 5V	nC
Input Capacitance (Ciss) (Max) @ Vds	528 @ 15V	pF
Power - Max	900	mW
Operating Temperature Range	-55 to 175	°C (TJ)
Configuration	2 P-Channel (Dual)	—
Package / Case	8-SOIC (0.154", 3.90mm Width)	—
Mounting Type	Surface Mount	—
Technology	MOSFET (Metal Oxide)	—
FET Feature	Logic Level Gate	—

Substitute Part Grouping Explanation

Substitute parts for the FDS4953 are evaluated based on the following critical parameters that determine functional compatibility:

Voltage Rating Compatibility: All substitute parts must maintain a Drain to Source Voltage (Vdss) rating of 30V or greater to ensure safe operation within the original design envelope.

Current Capacity: Substitute parts must support a continuous drain current (Id) at 25°C that meets or exceeds the 5A requirement of the FDS4953. Parts with lower current ratings are suitable only for applications with reduced current demands.

Package Configuration: All substitute parts must utilize the 8-SOIC surface mount package with 0.154" (3.90mm) width to ensure mechanical and electrical compatibility with existing PCB layouts.

Dual P-Channel Configuration: Substitute parts must maintain the 2 P-Channel (Dual) MOSFET array configuration to preserve circuit functionality.

Logic Level Gate Drive: Substitute parts must support logic level gate drive characteristics to maintain compatibility with standard digital control circuits.

Operating Temperature Range: Substitute parts must support the minimum operating temperature of -55°C. The FDS4953 upper temperature limit of 175°C is not matched by all substitutes; parts with 150°C maximum ratings are acceptable for applications not requiring extended high-temperature operation.

Thermal Characteristics: Maximum power dissipation ratings of 900mW or greater are preferred to maintain thermal margin equivalent to the original design.

Parameter Comparison

Parameter	FDS4953	FDS4935BZ	NTMD3P03R2G	AO4803A	TSM4953DCS RLG	ZXMP3A16DN8TA
Manufacturer	onsemi	onsemi	onsemi	Alpha & Omega Semiconductor Inc.	Taiwan Semiconductor Corporation	Diodes Incorporated
Vdss (V)	30	30	30	30	30	30
Id @ 25°C (A)	5	6.9	2.34	5	4.9	4.2
Rds On (Max) (mOhm)	55 @ 5A, 10V	22 @ 6.9A, 10V	85 @ 3.05A, 10V	46 @ 5A, 10V	60 @ 4.9A, 10V	45 @ 4.2A, 10V
Vgs(th) (Max) (V)	3 @ 250µA	3 @ 250µA	2.5 @ 250µA	2.5 @ 250µA	3 @ 250µA	1 @ 250µA (Min)
Gate Charge (Qg) (nC)	9 @ 5V	40 @ 10V	25 @ 10V	11 @ 10V	28 @ 10V	29.6 @ 10V
Input Capacitance (Ciss) (pF)	528 @ 15V	1360 @ 15V	750 @ 24V	520 @ 15V	745 @ 15V	1022 @ 15V
Power - Max (mW)	900	900	730	2000	2500	1800
Operating Temperature (°C)	-55 to 175	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150
Configuration	2 P-Channel (Dual)	2 P-Channel (Dual)	2 P-Channel (Dual)	2 P-Channel (Dual)	2 P-Channel (Dual)	2 P-Channel (Dual)
Package / Case	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC
FET Feature	Logic Level Gate	Logic Level Gate	Logic Level Gate	Logic Level Gate	—	Logic Level Gate
Product Status	Obsolete	Active	Active	Not For New Designs	Not For New Designs	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitute: FDS4935BZ

The FDS4935BZ is the recommended primary substitute for the FDS4953. Both devices are manufactured by onsemi within the PowerTrench® series and share identical voltage and package specifications. The FDS4935BZ provides enhanced current capacity (6.9A versus 5A) and superior on-resistance characteristics (22mOhm versus 55mOhm), delivering improved thermal performance and reduced power dissipation. The FDS4935BZ maintains Active product status with ROHS3 compliance, ensuring long-term availability and regulatory alignment. The primary limitation is the reduced maximum operating temperature of 150°C compared to the FDS4953's 175°C rating; this is acceptable for applications not requiring extended high-temperature operation.

Secondary Substitute: ZXMP3A16DN8TA

The ZXMP3A16DN8TA manufactured by Diodes Incorporated is an Active product offering compatible voltage and package specifications with current capacity of 4.2A. This device provides lower on-resistance (45mOhm) and superior gate charge characteristics compared to the FDS4953. The ZXMP3A16DN8TA maintains ROHS3 compliance and unlimited moisture sensitivity rating. This substitute is suitable for applications where the 4.2A current rating is sufficient and where the lower gate charge is beneficial for switching speed optimization.

Tertiary Substitute: AO4803A

The AO4803A manufactured by Alpha & Omega Semiconductor Inc. provides exact current matching (5A) and compatible voltage and package specifications. This device features lower on-resistance (46mOhm) and enhanced power dissipation capability (2W). However, the AO4803A carries a "Not For New Designs" product status, limiting its suitability for new applications. This substitute is appropriate for legacy system maintenance where component availability is constrained.

Not Recommended: NTMD3P03R2G

The NTMD3P03R2G provides insufficient continuous drain current (2.34A) relative to the FDS4953 requirement (5A). This device is suitable only for applications with significantly reduced current demands and should not be selected as a direct substitute for the FDS4953 in its original application context.

Not Recommended: TSM4953DCS RLG

The TSM4953DCS RLG carries a "Not For New Designs" product status and exhibits higher gate charge (28nC) and on-resistance (60mOhm) characteristics. The reduced maximum operating temperature (150°C) and elevated moisture sensitivity level (MSL 3) further limit its suitability as a primary substitute.

Frequently Asked Questions (FAQ)

Q: Can the FDS4935BZ directly replace the FDS4953 in existing designs?

A: The FDS4935BZ is mechanically and electrically compatible with the FDS4953 in the 8-SOIC package. Both devices share identical voltage ratings (30V), dual P-channel configuration, and logic level gate drive characteristics. The FDS4935BZ provides superior electrical performance with higher current capacity (6.9A) and lower on-resistance (22mOhm). The primary consideration is the reduced maximum operating temperature (150°C versus 175°C); applications operating above 150°C junction temperature require thermal analysis to confirm compatibility.

Q: What is the significance of the on-resistance (Rds On) parameter in selecting a substitute?

A: On-resistance directly determines power dissipation and thermal performance. Lower on-resistance values reduce heat generation during operation. The FDS4953 specifies 55mOhm at 5A and 10V gate voltage. Substitute parts with lower on-resistance values (such as FDS4935BZ at 22mOhm) provide improved thermal characteristics and reduced power loss. Substitute parts with higher on-resistance values (such as NTMD3P03R2G at 85mOhm) generate additional heat and may require thermal margin verification.

Q: Why do some substitute parts have different gate charge specifications?

A: Gate charge (Qg) represents the total charge required to switch the MOSFET from off to on state. The FDS4953 specifies 9nC at 5V gate voltage. Substitute parts measured at different gate voltages (typically 10V) exhibit different gate charge values. Higher gate charge values require longer switching times and increased driver current capability. Lower gate charge values enable faster switching and reduce driver power requirements. Gate charge differences should be evaluated in the context of the specific gate driver circuit used in the application.

Q: Is the 8-SOIC package identical across all substitute parts?

A: All substitute parts specified in this reference utilize the 8-SOIC package with 0.154" (3.90mm) width, ensuring mechanical compatibility with existing PCB layouts. However, the supplier device package designation may vary (8-SOP for TSM4953DCS RLG, 8-SO for ZXMP3A16DN8TA). These designations refer to the same physical package footprint and are interchangeable for PCB assembly purposes.

Q: What does "Logic Level Gate" mean, and why is it important?

A: Logic Level Gate indicates that the MOSFET is designed to operate with standard digital logic voltage levels (typically 3.3V or 5V). The FDS4953 and most substitute parts feature this characteristic, enabling direct interface with microcontroller and digital circuit outputs without requiring additional gate drive voltage translation. The NTMD3P03R2G and ZXMP3A16DN8TA exhibit lower gate threshold voltages (2.5V and 1V respectively), providing enhanced compatibility with lower voltage logic systems.

Q: How does product status affect substitute part selection?

A: Product status indicates manufacturer support and long-term availability. Active products (FDS4935BZ, ZXMP3A16DN8TA) are recommended for new designs and ongoing production due to guaranteed availability and manufacturer support. Obsolete products (FDS4953) and "Not For New Designs" products (AO4803A, TSM4953DCS RLG) are suitable for legacy system maintenance and repair but should not be selected for new applications. Active product status provides assurance of continued supply and technical support.

Q: What is ROHS3 compliance, and why is it relevant?

A: ROHS3 compliance indicates conformance to the Restriction of Hazardous Substances Directive, restricting the use of specified hazardous materials in electrical and electronic equipment. All substitute parts except the FDS4953 carry ROHS3 compliance certification. This compliance is increasingly required for products sold in regulated markets and ensures environmental and health safety standards are met.

Q: Can the NTMD3P03R2G be used in applications requiring less than 5A continuous current?

A: The NTMD3P03R2G with 2.34A continuous drain current rating is suitable only for applications with current requirements below 2.34A. Using this device in applications designed for 5A operation would result in thermal stress, reduced reliability, and potential device failure. Current capacity must be matched to the actual application requirements, not the original design specification.

Q: What thermal considerations apply when selecting between substitute parts?

A: Maximum power dissipation ratings vary across substitute parts: FDS4953 (900mW), FDS4935BZ (900mW), NTMD3P03R2G (730mW), AO4803A (2000mW), TSM4953DCS RLG (2500mW), and ZXMP3A16DN8TA (1800mW). Higher power ratings provide greater thermal margin. Actual power dissipation depends on on-resistance and operating current. Applications with tight thermal constraints should prioritize substitute parts with lower on-resistance values and higher power ratings.

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