IRFU120 N-Channel MOSFET 100V 7.7A TO-251AA Equivalent & Substitute Parts

Part Overview

The IRFU120 is an N-Channel MOSFET manufactured by Vishay Siliconix, rated for 100V drain-to-source voltage with 7.7A continuous drain current at 25°C. The device is packaged in TO-251AA (IPAK) through-hole configuration and is designed for general-purpose switching applications requiring moderate power dissipation (2.5W at Ta, 42W at Tc).

The IRFU120 is classified as obsolete. Equivalent and substitute parts are available from active product lines, making substitution necessary for new designs and ongoing procurement. Substitute parts maintain electrical compatibility while offering improved availability and compliance status.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	100	V
Continuous Drain Current (Id) @ 25°C	7.7	A (Tc)
Drive Voltage (Max Rds On)	10	V
Rds On (Max) @ Id, Vgs	270	mOhm @ 4.6A, 10V
Gate Threshold Voltage Vgs(th) (Max) @ Id	4	V @ 250µA
Gate Charge (Qg) (Max) @ Vgs	16	nC @ 10V
Maximum Gate Voltage (Vgs)	±20	V
Input Capacitance (Ciss) (Max) @ Vds	360	pF @ 25V
Power Dissipation (Max)	2.5 / 42	W (Ta) / W (Tc)
Operating Temperature Range (TJ)	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-251-3 Short Leads, IPak, TO-251AA	—
Technology	MOSFET (Metal Oxide)	—

Substitute Part Grouping Explanation

Substitute parts for the IRFU120 are selected based on strict electrical and mechanical compatibility criteria. All substitute parts must satisfy the following requirements:

Mandatory Compatibility Criteria:

FET Type: N-Channel
Technology: MOSFET (Metal Oxide)
Drain-to-Source Voltage (Vdss): 100V (equal or greater)
Continuous Drain Current (Id): Equal to or greater than 7.7A
Gate Threshold Voltage (Vgs(th)): 4V @ 250µA (matching specification)
Maximum Gate Voltage (Vgs): ±20V (equal or greater)
Mounting Type: Through Hole
Package / Case: TO-251-3 Short Leads, IPak, TO-251AA (mechanical compatibility)

Substitute Parts Identified:

IRFU120PBF (Vishay Siliconix) – Parametric equivalent with identical electrical specifications and active product status
IRFU120NPBF (Infineon Technologies) – Enhanced performance substitute with higher drain current (9.4A) and improved thermal characteristics
STU6NF10 (STMicroelectronics) – Functional substitute with lower drain current (6A) for applications not requiring full 7.7A capacity

Parameter Comparison

Parameter	IRFU120	IRFU120PBF	IRFU120NPBF	STU6NF10
Manufacturer	Vishay Siliconix	Vishay Siliconix	Infineon Technologies	STMicroelectronics
Product Status	Obsolete	Active	Active	Active
Vdss (V)	100	100	100	100
Id @ 25°C (A)	7.7	7.7	9.4	6.0
Rds On (Max) @ 10V (mOhm)	270 @ 4.6A	270 @ 4.6A	210 @ 5.6A	250 @ 3A
Vgs(th) (Max) @ 250µA (V)	4	4	4	4
Gate Charge Qg (Max) @ 10V (nC)	16	16	25	14
Ciss (Max) @ 25V (pF)	360	360	330	280
Vgs (Max) (V)	±20	±20	±20	±20
Power Dissipation (Max) (W)	2.5 (Ta) / 42 (Tc)	2.5 (Ta) / 42 (Tc)	48 (Tc)	30 (Tc)
Operating Temperature (°C)	-55 to 150	-55 to 150	-55 to 175	-65 to 175
Package / Case	TO-251AA	TO-251AA	IPAK (TO-251AA)	TO-251 (IPAK)
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Inventory Status	2106 Pcs	15165 Pcs	110300 Pcs	15426 Pcs

Engineering Selection Recommendations

IRFU120PBF (Vishay Siliconix) – Direct Parametric Equivalent

IRFU120PBF is the primary substitute for IRFU120. It maintains identical electrical specifications (100V, 7.7A, 270mOhm Rds On, 16nC gate charge) and mechanical compatibility (TO-251AA package). The part is in active production status with superior availability (15165 units in stock versus 2106 for the obsolete IRFU120). IRFU120PBF is ROHS3 compliant, addressing regulatory requirements for new designs. This part is recommended for direct replacement in existing applications without circuit modification.

IRFU120NPBF (Infineon Technologies) – Enhanced Performance Substitute

IRFU120NPBF is suitable for applications where improved performance margins are beneficial. It provides higher continuous drain current (9.4A versus 7.7A) and superior on-resistance (210mOhm versus 270mOhm at comparable conditions), resulting in lower power dissipation and improved thermal performance (48W Tc versus 42W Tc). The extended operating temperature range (-55°C to 175°C versus -55°C to 150°C) provides additional thermal margin. Gate charge is higher (25nC versus 16nC), which may affect switching speed in high-frequency applications. IRFU120NPBF is ROHS3 compliant with exceptional inventory availability (110300 units). This part is recommended for new designs or applications requiring enhanced current capacity and thermal performance.

STU6NF10 (STMicroelectronics) – Functional Substitute for Current-Limited Applications

STU6NF10 is suitable only for applications where the required drain current does not exceed 6A. The part maintains 100V Vdss rating and TO-251 (IPAK) package compatibility. STU6NF10 offers lower gate charge (14nC) and input capacitance (280pF), which may provide faster switching characteristics in low-current circuits. Power dissipation is rated at 30W Tc. The extended operating temperature range (-65°C to 175°C) exceeds IRFU120 specifications. STU6NF10 is ROHS3 compliant with adequate inventory (15426 units). This part is recommended only for applications where 6A continuous drain current is sufficient and switching speed is a priority.

Frequently Asked Questions (FAQ)

Q1: Can IRFU120PBF be used as a direct replacement for IRFU120 without circuit modification?

Yes. IRFU120PBF is a parametric equivalent with identical electrical specifications (100V Vdss, 7.7A Id, 270mOhm Rds On, 16nC Qg) and mechanical compatibility (TO-251AA package). No circuit changes are required. The primary difference is product status (active versus obsolete) and RoHS compliance (ROHS3 compliant versus non-compliant).

Q2: What are the key differences between IRFU120NPBF and IRFU120?

IRFU120NPBF provides higher drain current (9.4A versus 7.7A), lower on-resistance (210mOhm versus 270mOhm), and higher power dissipation capability (48W Tc versus 42W Tc). Gate charge is higher (25nC versus 16nC), which may increase switching losses in high-frequency applications. Operating temperature range is extended to 175°C. All parts maintain 100V Vdss and TO-251AA package compatibility.

Q3: When should STU6NF10 be selected instead of IRFU120PBF or IRFU120NPBF?

STU6NF10 should be selected only when the application requires drain current not exceeding 6A. The lower gate charge (14nC) and input capacitance (280pF) may provide faster switching characteristics in low-current, high-frequency circuits. For applications requiring the full 7.7A rating, IRFU120PBF or IRFU120NPBF are required.

Q4: Are all substitute parts mechanically compatible with the original IRFU120 PCB layout?

Yes. All substitute parts (IRFU120PBF, IRFU120NPBF, STU6NF10) use TO-251-3 Short Leads, IPak, or TO-251AA package configurations with identical pin spacing and through-hole mounting. No PCB modification is required for mechanical installation.

Q5: What is the RoHS compliance status of each substitute part?

IRFU120PBF, IRFU120NPBF, and STU6NF10 are all ROHS3 compliant. The original IRFU120 is RoHS non-compliant. For applications subject to RoHS regulations, any of the three substitute parts satisfy compliance requirements.

Q6: Which substitute part offers the best thermal performance?

IRFU120NPBF offers the best thermal performance with 48W Tc power dissipation rating and lower on-resistance (210mOhm). This results in lower junction temperature rise under identical load conditions compared to IRFU120 (42W Tc) or STU6NF10 (30W Tc).

Q7: How do gate charge differences affect circuit performance?

Gate charge (Qg) determines the energy required to switch the MOSFET. IRFU120 and IRFU120PBF require 16nC, IRFU120NPBF requires 25nC, and STU6NF10 requires 14nC. Higher gate charge increases switching losses and may require higher gate drive current. Lower gate charge reduces switching losses and gate drive requirements. Selection depends on the gate driver circuit capability and switching frequency.

Q8: What inventory considerations should guide part selection?

IRFU120NPBF has the highest inventory availability (110300 units), followed by IRFU120PBF (15165 units) and STU6NF10 (15426 units). The original IRFU120 has limited inventory (2106 units) and is obsolete. For long-term supply chain security, IRFU120NPBF is recommended.

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