FQD24N08TM Equivalent & Substitute Parts

Part Overview

The FQD24N08TM is an N-Channel MOSFET manufactured by onsemi, rated for 80V drain-to-source voltage with 19.6A continuous drain current. The device is housed in a TO-252AA (DPAK) surface mount package and is classified as obsolete. Due to its obsolete status, equivalent substitute parts with compatible electrical and mechanical specifications are necessary for ongoing design support and production continuity.

Key Parameters

Parameter	Value
Drain-to-Source Voltage (Vdss)	80 V
Continuous Drain Current (Id) @ 25°C	19.6 A (Tc)
On-Resistance (Rds On) @ 10V	60 mOhm @ 9.8A, 10V
Gate Threshold Voltage (Vgs(th))	4 V @ 250µA
Gate Charge (Qg) @ 10V	25 nC
Input Capacitance (Ciss) @ 25V	750 pF
Power Dissipation (Max)	2.5W (Ta), 50W (Tc)
Operating Temperature Range	-55°C to 150°C (TJ)
Package Type	TO-252-3, DPAK (2 Leads + Tab), SC-63
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution of the FQD24N08TM is determined by the following critical parameters:

Voltage Rating Compatibility: Substitute parts must have a Vdss rating equal to or greater than 80V to ensure safe operation in the original circuit.

Current Rating Compatibility: Substitute parts must have a continuous drain current (Id) rating equal to or greater than 19.6A to handle the design load without thermal stress.

On-Resistance (Rds On): Substitute parts must have comparable or lower on-resistance at the specified gate voltage to maintain similar power dissipation characteristics and thermal performance.

Package Compatibility: All substitute parts must use the TO-252-3 DPAK surface mount package to ensure mechanical and thermal interface compatibility with existing PCB layouts.

Gate Threshold Voltage (Vgs(th)): Substitute parts must have compatible gate threshold voltage to ensure proper switching behavior with existing gate drive circuits.

Operating Temperature Range: Substitute parts must support the required operating temperature range to maintain reliability across the application's thermal envelope.

The following substitute parts meet these criteria:

FDD3690 (onsemi): 100V, 22A, DPAK, Active status
STD15NF10T4 (STMicroelectronics): 100V, 23A, DPAK, Active status
STD25NF10LT4 (STMicroelectronics): 100V, 25A, DPAK, Active status
STD25NF10T4 (STMicroelectronics): 100V, 25A, DPAK, Active status

Parameter Comparison

Parameter	FQD24N08TM	FDD3690	STD15NF10T4	STD25NF10LT4	STD25NF10T4
Manufacturer	onsemi	onsemi	STMicroelectronics	STMicroelectronics	STMicroelectronics
Vdss (V)	80	100	100	100	100
Id @ 25°C (A)	19.6	22	23	25	25
Rds On (mOhm) @ 10V	60 @ 9.8A	64 @ 5.4A	65 @ 12A	35 @ 12.5A	38 @ 12.5A
Vgs(th) (V) @ 250µA	4	4	4	2.5	4
Qg (nC) @ 10V	25	39	40	52	55
Ciss (pF) @ 25V	750	1514	870	1710	1550
Power Dissipation (W) @ Tc	50	60	70	100	100
Operating Temperature (°C)	-55 to 150	-55 to 175	-55 to 175	-55 to 175	-55 to 175
Package	TO-252-3, DPAK	TO-252-3, DPAK	TO-252-3, DPAK	TO-252-3, DPAK	TO-252-3, DPAK
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	REACH Unaffected	REACH Unaffected	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: STD25NF10LT4

The STD25NF10LT4 is the preferred substitute for the FQD24N08TM. This part exceeds the original specifications in voltage rating (100V vs. 80V), current capacity (25A vs. 19.6A), and power dissipation (100W vs. 50W). The device is manufactured by STMicroelectronics, carries active product status, and is ROHS3 compliant. The lower on-resistance (35 mOhm at 10V) provides improved thermal performance compared to the original part. The extended operating temperature range (-55°C to 175°C) supports broader application requirements. High inventory availability (688,200 units) ensures supply continuity.

Secondary Recommendation: STD25NF10T4

The STD25NF10T4 offers equivalent performance to the STD25NF10LT4 with slightly higher on-resistance (38 mOhm at 10V). This part maintains active product status, ROHS3 compliance, and superior voltage/current ratings. Inventory availability exceeds 1,000,100 units, providing exceptional supply security.

Alternative Recommendation: FDD3690

The FDD3690 is an onsemi-manufactured substitute maintaining the same manufacturer lineage as the original part. It provides 100V voltage rating and 22A current capacity with active product status. This option is suitable for applications where manufacturer continuity is preferred, though it offers lower current capacity than the STMicroelectronics alternatives.

Alternative Recommendation: STD15NF10T4

The STD15NF10T4 provides 100V voltage rating and 23A current capacity with active product status and ROHS3 compliance. This part is suitable for applications with moderate current requirements and offers 70W power dissipation capability.

Frequently Asked Questions (FAQ)

Q: Can the FQD24N08TM be directly replaced with any of these substitute parts?

A: Yes. All listed substitute parts are pin-compatible in the TO-252-3 DPAK package and exceed or match the electrical specifications of the FQD24N08TM. Direct PCB substitution is possible without layout modifications.

Q: What is the primary reason for substitution?

A: The FQD24N08TM is classified as obsolete. The substitute parts listed are all active products with confirmed long-term availability and supply continuity.

Q: Do the substitute parts have higher voltage ratings than the original?

A: Yes. All substitute parts are rated for 100V Vdss compared to the original 80V rating. This higher voltage rating provides additional design margin and does not negatively impact circuit operation.

Q: How do the current ratings compare?

A: All substitute parts exceed the original 19.6A rating. FDD3690 provides 22A, STD15NF10T4 provides 23A, and both STD25NF10LT4 and STD25NF10T4 provide 25A. Higher current ratings ensure the substitute parts handle the design load without thermal stress.

Q: Are there differences in on-resistance that affect circuit performance?

A: Yes. The STD25NF10LT4 offers the lowest on-resistance at 35 mOhm (10V), compared to the original 60 mOhm. Lower on-resistance reduces power dissipation and improves thermal performance. The STD25NF10T4 provides 38 mOhm, FDD3690 provides 64 mOhm, and STD15NF10T4 provides 65 mOhm. All values are acceptable for direct substitution.

Q: What is the difference between STD25NF10LT4 and STD25NF10T4?

A: Both parts are rated for 100V and 25A with identical package specifications. The primary difference is on-resistance: STD25NF10LT4 has 35 mOhm at 10V, while STD25NF10T4 has 38 mOhm at 10V. The STD25NF10LT4 also has a lower gate threshold voltage (2.5V vs. 4V). Both are suitable substitutes; selection depends on specific thermal and switching requirements.

Q: Are all substitute parts RoHS compliant?

A: The STMicroelectronics parts (STD15NF10T4, STD25NF10LT4, STD25NF10T4) are ROHS3 compliant. The FDD3690 is REACH unaffected. All parts meet environmental compliance requirements for modern manufacturing standards.

Q: What is the operating temperature range for each substitute?

A: The FQD24N08TM operates from -55°C to 150°C. All substitute parts extend this range to -55°C to 175°C, providing improved thermal margin for high-temperature applications.

Q: Which substitute part has the best inventory availability?

A: STD25NF10T4 has the highest inventory with over 1,000,100 units in stock, followed by STD25NF10LT4 with 688,200 units. Both ensure long-term supply security.

Q: Can I use these parts interchangeably in the same design?

A: Yes. All substitute parts are mechanically and electrically compatible for direct PCB substitution. However, if gate drive timing is critical, note that gate charge (Qg) values vary: FQD24N08TM has 25 nC, while substitutes range from 39 to 55 nC. Verify gate drive circuit capability for higher Qg values.

Q: What package considerations apply to these substitutes?

A: All substitute parts use the TO-252-3 DPAK (2 Leads + Tab) surface mount package, identical to the original FQD24N08TM. No PCB layout modifications are required for mechanical compatibility or thermal interface.

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