FQD2N40TM Equivalent & Substitute Parts

Part Overview

The FQD2N40TM is an N-Channel MOSFET manufactured by onsemi, rated for 400V drain-to-source voltage with 1.4A continuous drain current at 25°C. The device is housed in a TO-252AA (DPAK) surface mount package and is classified as obsolete. Due to its obsolete status, identifying equivalent substitute components is necessary to maintain design continuity and ensure component availability for production and repair applications.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	400	V
Current - Continuous Drain (Id) @ 25°C	1.4	A
Rds On (Max) @ Id, Vgs	5.8 @ 700mA, 10V	Ohm
Vgs(th) (Max) @ Id	5 @ 250µA	V
Vgs (Max)	±30	V
Power Dissipation (Max)	2.5 (Ta), 25 (Tc)	W
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-252-3, DPAK (2 Leads + Tab), SC-63	—

Substitute Part Grouping Explanation

Substitution of the FQD2N40TM is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

Drain-to-Source Voltage (Vdss): Must equal or exceed 400V
Continuous Drain Current (Id): Must support the application's current requirements
On-State Resistance (Rds On): Must be compatible with thermal and switching loss budgets
Gate Threshold Voltage (Vgs(th)): Must be compatible with gate drive circuitry
Maximum Gate Voltage (Vgs Max): Must accommodate the gate drive voltage range
Operating Temperature Range: Must cover -55°C to 150°C

Mechanical Compatibility Criteria:

Mounting Type: Surface Mount
Package / Case: TO-252-3 (DPAK) form factor with identical pin configuration

The TN2640K4-G from Microchip Technology meets these substitution criteria through equivalent voltage rating, compatible package geometry, and overlapping thermal specifications.

Parameter Comparison

Parameter	FQD2N40TM (onsemi)	TN2640K4-G (Microchip)	Unit
FET Type	N-Channel	N-Channel	—
Technology	MOSFET (Metal Oxide)	MOSFET (Metal Oxide)	—
Drain to Source Voltage (Vdss)	400	400	V
Current - Continuous Drain (Id) @ 25°C	1.4 (Tc)	0.5 (Tj)	A
Rds On (Max) @ Id, Vgs	5.8 @ 700mA, 10V	5 @ 500mA, 10V	Ohm
Vgs(th) (Max) @ Id	5 @ 250µA	2 @ 2mA	V
Vgs (Max)	±30	±20	V
Input Capacitance (Ciss) (Max) @ Vds	150 @ 25V	225 @ 25V	pF
Power Dissipation (Max)	2.5 (Ta), 25 (Tc)	2.5 (Ta)	W
Operating Temperature	-55 to 150	-55 to 150	°C
Mounting Type	Surface Mount	Surface Mount	—
Package / Case	TO-252-3, DPAK (2 Leads + Tab), SC-63	TO-252-3, DPAK (2 Leads + Tab), SC-63	—

Engineering Selection Recommendations

FQD2N40TM (onsemi) — Obsolete Status: The FQD2N40TM is classified as obsolete and is no longer in active production. While 946 pieces remain in stock from the original manufacturer, long-term availability cannot be assured. This part should be considered for legacy system maintenance only.

TN2640K4-G (Microchip Technology) — Active Status: The TN2640K4-G is an active production component from Microchip Technology with 20,495 pieces currently in stock. This device is RoHS3 compliant and carries REACH Unaffected status, meeting modern regulatory requirements. The part is available in Tape & Reel packaging, suitable for automated assembly processes.

Substitution Basis: Both devices share identical voltage ratings (400V Vdss), equivalent on-state resistance characteristics, compatible package geometry (TO-252 DPAK), and overlapping operating temperature ranges (-55°C to 150°C). The TN2640K4-G provides superior long-term availability and regulatory compliance for new designs and production continuity.

Frequently Asked Questions (FAQ)

Q: Can the TN2640K4-G directly replace the FQD2N40TM in existing designs?

A: The TN2640K4-G is mechanically and electrically compatible with the FQD2N40TM. Both devices use the TO-252 DPAK package with identical pin configuration. Electrical parameters including Vdss (400V), Rds On characteristics, and operating temperature range (-55°C to 150°C) are compatible. However, the TN2640K4-G has a lower continuous drain current rating (500mA vs. 1.4A) and a lower maximum gate voltage (±20V vs. ±30V). Circuit designs must verify that application current requirements do not exceed 500mA and that gate drive voltages remain within ±20V limits.

Q: What are the key differences between these two devices?

A: The primary differences are: (1) Continuous drain current: FQD2N40TM supports 1.4A while TN2640K4-G supports 500mA; (2) Maximum gate voltage: FQD2N40TM allows ±30V while TN2640K4-G allows ±20V; (3) Gate threshold voltage: FQD2N40TM has 5V threshold at 250µA while TN2640K4-G has 2V threshold at 2mA; (4) Input capacitance: TN2640K4-G has higher Ciss (225pF vs. 150pF); (5) Product status: FQD2N40TM is obsolete while TN2640K4-G is active production.

Q: Are there packaging differences between these parts?

A: Both devices use the TO-252-3 DPAK (2 Leads + Tab) surface mount package with identical mechanical dimensions and pin assignments. The TN2640K4-G is supplied in Tape & Reel packaging suitable for automated pick-and-place assembly, while the FQD2N40TM packaging format is not specified in available documentation.

Q: What compliance certifications apply to each device?

A: The FQD2N40TM carries REACH Unaffected status and EAR99 export classification. The TN2640K4-G is RoHS3 compliant, REACH Unaffected, and carries EAR99 export classification. Both devices have identical HTSUS codes (8541.29.0095).

Q: Which device should be selected for new production designs?

A: The TN2640K4-G should be selected for new production designs due to its active production status, superior availability (20,495 units in stock), RoHS3 compliance, and Tape & Reel packaging for automated assembly. The FQD2N40TM should be reserved for legacy system maintenance where the higher current rating (1.4A) or extended gate voltage range (±30V) is specifically required.

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