Equivalent & Substitute Parts for BUT11A

Part Overview

The BUT11A is an NPN bipolar junction transistor manufactured by onsemi, rated for 450 V collector-emitter breakdown voltage and 5 A maximum collector current in a TO-220-3 through-hole package. This device is classified as Last Time Buy, indicating discontinued production with limited inventory availability. The identification of equivalent and substitute parts addresses the need for alternative sourcing options for ongoing production requirements and long-term component availability planning.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	-
Voltage - Collector Emitter Breakdown (Max)	450	V
Current - Collector (Ic) (Max)	5	A
Power - Max	100	W
Vce Saturation (Max) @ Ib, Ic	1.5V @ 500mA, 2.5A	-
Current - Collector Cutoff (Max)	1	mA
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	-
Package / Case	TO-220-3	-
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution eligibility for the BUT11A is determined by the following critical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (mandatory match)
Voltage - Collector Emitter Breakdown (Max): 400 V minimum, 450 V or higher acceptable
Current - Collector (Ic) (Max): 5 A minimum required
Mounting Type: Through Hole (mandatory match)
Package / Case: TO-220-3 or compatible TO-220 variants
Operating Temperature: 150°C (TJ) minimum

Secondary Compatibility Factors:

Power dissipation rating: 80 W or higher acceptable
Vce Saturation characteristics: Lower saturation voltage preferred for efficiency
RoHS compliance status: ROHS3 Compliant or equivalent

Substitute parts are grouped into two categories: direct equivalents (matching all primary criteria) and functional alternatives (meeting minimum electrical requirements with acceptable parameter variations).

Parameter Comparison

Part Number	Manufacturer	Ic (Max) [A]	Vce Breakdown (Max) [V]	Power (Max) [W]	Vce Sat @ Ib, Ic	Package	Product Status
BUT11A	onsemi	5	450	100	1.5V @ 500mA, 2.5A	TO-220-3	Last Time Buy
BUT11AFTU	onsemi	5	450	40	1.5V @ 500mA, 2.5A	TO-220F-3	Active
BUL38D	STMicroelectronics	5	450	80	1.1V @ 750mA, 3A	TO-220	Active
BUL49D	STMicroelectronics	5	450	80	1.2V @ 800mA, 4A	TO-220	Active
BUL58D	STMicroelectronics	8	450	85	2V @ 1A, 5A	TO-220	Active
BUJD203A,127	WeEn Semiconductors	4	425	80	1V @ 600mA, 3A	TO-220AB	Active
MJE18008G	onsemi	8	450	125	700mV @ 900mA, 4.5A	TO-220	Active
BUL742C	STMicroelectronics	4	400	70	1.5V @ 1A, 3.5A	TO-220	Active
ST13005	STMicroelectronics	4	400	75	1V @ 1A, 4A	TO-220	Active
TSC742CZ C0G	Taiwan Semiconductor Corporation	5	420	70	1.5V @ 1A, 3.5A	TO-220	Active

Engineering Selection Recommendations

Direct Equivalent (Recommended Primary Substitute):

BUT11AFTU is the manufacturer-recommended equivalent from onsemi. This part maintains identical electrical specifications (5 A, 450 V, 1.5V saturation voltage) and shares the same base product number (BUT11). The primary difference is packaging format (TO-220F-3 full pack versus bulk TO-220-3) and reduced power rating (40 W versus 100 W). This part is in Active product status, ensuring long-term availability. Selection of BUT11AFTU is appropriate for applications where the 40 W power rating is sufficient.

High-Current Alternatives (5 A or Greater):

BUL38D and BUL49D from STMicroelectronics both provide 5 A collector current at 450 V breakdown voltage with 80 W power ratings. Both parts are in Active status with substantial inventory availability. BUL38D exhibits lower saturation voltage (1.1V) compared to the BUT11A baseline, offering improved efficiency characteristics. BUL49D provides comparable performance with slightly higher saturation voltage (1.2V).

BUL58D provides 8 A collector current at 450 V, exceeding the BUT11A current rating. This part is suitable for applications requiring higher current capacity with the same voltage rating. Power rating of 85 W accommodates higher current operation.

MJE18008G from onsemi offers 8 A at 450 V with 125 W power rating and includes transition frequency specification (13 MHz), indicating suitability for switching applications. This part is in Active status with high inventory availability.

Lower-Current Alternatives (4 A):

BUJD203A,127 from WeEn Semiconductors provides 4 A at 425 V, meeting minimum voltage requirements with reduced current capacity. This part is suitable for applications where 4 A collector current is acceptable.

BUL742C and ST13005 from STMicroelectronics both operate at 400 V breakdown voltage, below the BUT11A specification. These parts are suitable only for applications with reduced voltage requirements.

TSC742CZ C0G from Taiwan Semiconductor Corporation provides 5 A at 420 V with 70 W power rating. This part meets current requirements with slightly reduced voltage margin.

Compliance and Availability:

All substitute parts listed maintain ROHS3 compliance or equivalent RoHS certification. All parts are in Active product status except the main part (Last Time Buy), ensuring continued availability for future procurement. Inventory levels for substitute parts range from 673 to 34,090 units, providing adequate supply for production planning.

Frequently Asked Questions (FAQ)

Q: Can BUT11AFTU be used as a direct replacement for BUT11A?

A: BUT11AFTU is the manufacturer-recommended equivalent with identical electrical specifications (5 A, 450 V, saturation voltage). The primary difference is packaging format (TO-220F-3 full pack versus bulk TO-220-3). Electrical performance is equivalent. Power rating reduction from 100 W to 40 W requires verification that application 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 packages with three leads. The TO-220F-3 designation indicates full pack configuration, typically used for tube packaging. The TO-220-3 standard designation applies to bulk packaging. Mechanical dimensions and electrical performance are equivalent.

Q: Can BUL58D or MJE18008G be used in place of BUT11A?

A: Both parts provide higher current capacity (8 A versus 5 A) at the same 450 V breakdown voltage. These parts are suitable for applications where the BUT11A is used, provided that circuit design accommodates the higher current rating. Both parts are in Active status with superior availability compared to the Last Time Buy BUT11A.

Q: Are there voltage derating considerations when selecting ST13005 or BUL742C?

A: ST13005 and BUL742C operate at 400 V breakdown voltage, compared to 450 V for BUT11A. These parts are suitable only for applications where the circuit operates below 400 V. For circuits designed for 450 V operation, these parts do not meet voltage requirements.

Q: What is the significance of transition frequency in MJE18008G?

A: MJE18008G includes transition frequency specification (13 MHz), indicating this part is optimized for switching applications. The BUT11A does not include transition frequency specification. MJE18008G is suitable for high-frequency switching circuits where transition frequency is a design parameter.

Q: How do saturation voltage differences affect circuit performance?

A: Lower saturation voltage reduces power dissipation in saturated switching applications. BUL38D exhibits 1.1V saturation versus 1.5V for BUT11A, resulting in approximately 27% lower saturation voltage. For linear amplifier applications, saturation voltage differences have minimal impact. For switching applications, lower saturation voltage improves efficiency.

Q: Is RoHS compliance maintained across all substitute parts?

A: All substitute parts listed maintain ROHS3 compliance or equivalent RoHS certification status. No compliance degradation occurs when selecting any listed substitute part.

Q: What inventory considerations apply to BUT11A sourcing?

A: BUT11A is classified as Last Time Buy with 2,368 units in stock. All substitute parts are in Active status with inventory ranging from 673 to 34,090 units. For long-term production planning, selection of Active status parts (BUL38D, BUL49D, BUL58D, MJE18008G, or BUT11AFTU) ensures continued availability.

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