BUH50 Equivalent & Substitute Parts

Part Overview

The BUH50 is an NPN bipolar junction transistor manufactured by onsemi, designed for high-voltage switching applications. Rated at 500 V collector-emitter breakdown voltage with 4 A maximum collector current, the BUH50 operates in the SWITCHMODE™ series and is packaged in a Through Hole TO-220-3 configuration. The device is classified as obsolete, necessitating identification of functionally equivalent active alternatives for new designs and ongoing production requirements.

Key Parameters

Parameter	Value
Transistor Type	NPN
Voltage - Collector Emitter Breakdown (Max)	500 V
Current - Collector (Ic) (Max)	4 A
Power - Max	50 W
Frequency - Transition	4 MHz
Package / Case	TO-220-3
Mounting Type	Through Hole
Operating Temperature	-65°C ~ 150°C (TJ)

Substitute Part Grouping Explanation

Substitution of the BUH50 is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

Transistor Type: NPN configuration required
Voltage - Collector Emitter Breakdown: Minimum 500 V (equal or higher acceptable)
Current - Collector (Ic) (Max): Minimum 4 A (equal or higher acceptable)
Power - Max: Minimum 50 W (equal or higher acceptable)

Mechanical Compatibility Criteria:

Mounting Type: Through Hole required
Package / Case: TO-220-3 or compatible TO-220 variant

All three substitute parts meet or exceed the electrical specifications of the BUH50 while maintaining Through Hole TO-220 package compatibility. The substitutes provide enhanced performance characteristics including higher current ratings (5 A), improved power dissipation (40-100 W), and higher transition frequencies (15 MHz), with the exception of BUL1203E which specifies 550 V breakdown voltage.

Parameter Comparison

Parameter	BUH50	FJPF5021OTU	BUJ303A,127	BUL1203E
Manufacturer	onsemi	onsemi	WeEn Semiconductors	STMicroelectronics
Transistor Type	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	500 V	500 V	500 V	550 V
Current - Collector (Ic) (Max)	4 A	5 A	5 A	5 A
Power - Max	50 W	40 W	100 W	100 W
Frequency - Transition	4 MHz	15 MHz	Not Specified	Not Specified
Package / Case	TO-220-3	TO-220-3 Full Pack	TO-220-3	TO-220-3
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

FJPF5021OTU (onsemi): This substitute maintains identical voltage and package specifications to the BUH50 while providing 25% higher collector current (5 A vs. 4 A). The device is ROHS3 compliant and carries active product status. Transition frequency is elevated to 15 MHz. Power dissipation is rated at 40 W, which is lower than the BUH50; applications requiring the full 50 W power envelope should be evaluated against actual thermal requirements.

BUJ303A,127 (WeEn Semiconductors): This substitute offers the highest power dissipation rating at 100 W with 5 A collector current and 500 V breakdown voltage. ROHS3 compliance and active product status are confirmed. This option provides the greatest thermal margin and is suitable for applications with demanding power requirements.

BUL1203E (STMicroelectronics): This substitute provides 550 V breakdown voltage (50 V higher than BUH50), 5 A collector current, and 100 W power dissipation. ROHS3 compliance and active product status are confirmed. The elevated voltage rating accommodates applications with higher transient voltage stress.

All three substitutes are active products with ROHS3 compliance, addressing the obsolescence and regulatory status of the BUH50.

Frequently Asked Questions (FAQ)

Q: Can FJPF5021OTU directly replace BUH50 in existing designs?

A: FJPF5021OTU meets the electrical requirements of BUH50 with equal voltage rating (500 V) and higher current capability (5 A vs. 4 A). Both use TO-220-3 Through Hole packaging. The primary consideration is power dissipation: FJPF5021OTU is rated at 40 W versus BUH50's 50 W. Verify that actual circuit power dissipation does not exceed 40 W.

Q: What is the difference between TO-220-3 and TO-220F-3 packaging?

A: Both are Through Hole TO-220 variants with three leads. TO-220F-3 (used by FJPF5021OTU) indicates a full pack configuration. Mechanical compatibility with standard TO-220-3 footprints is maintained. Consult device datasheets for specific lead spacing and mounting hole requirements.

Q: Why does BUL1203E have a higher voltage rating (550 V) than BUH50 (500 V)?

A: The 550 V rating provides additional margin for transient overvoltage conditions. This higher rating does not prevent substitution; circuits designed for 500 V operation remain compatible. The higher voltage rating may reduce switching losses in high-voltage applications.

Q: Are all three substitutes RoHS compliant?

A: Yes. FJPF5021OTU, BUJ303A,127, and BUL1203E are all ROHS3 compliant. The BUH50 is RoHS non-compliant, making these substitutes necessary for applications requiring regulatory compliance.

Q: Which substitute offers the best thermal performance?

A: BUJ303A,127 and BUL1203E both provide 100 W power dissipation, double that of BUH50. FJPF5021OTU is rated at 40 W. Selection depends on actual circuit power dissipation requirements and thermal management design.

Q: Can these substitutes be used interchangeably in the same circuit?

A: All three substitutes meet the minimum electrical specifications of BUH50 and use compatible Through Hole TO-220 packaging. However, differences in power dissipation (40 W vs. 100 W) and transition frequency (4 MHz vs. 15 MHz) may affect circuit performance. Verify compatibility with specific application requirements before implementation.

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