BD543C-S Equivalent & Substitute Parts

Part Overview

The BD543C-S is an NPN bipolar junction transistor manufactured by Bourns Inc., rated for 100 V collector-emitter breakdown voltage and 8 A maximum collector current in a TO-220 through-hole package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The 2 W power rating and specified operating temperature range of -65°C to 150°C define its application envelope for medium-power switching and amplification circuits.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	100	V
Current - Collector (Ic) (Max)	8	A
Power - Max	2	W
Vce Saturation (Max)	1	V @ 1.6A, 8A
DC Current Gain (hFE) (Min)	15	@ 5A, 4V
Current - Collector Cutoff (Max)	700	µA
Operating Temperature	-65 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-220-3	—

Substitute Part Grouping Explanation

Substitution of the BD543C-S is determined by matching the following critical electrical and mechanical parameters:

Primary Matching Criteria:

Transistor Type: NPN
Voltage - Collector Emitter Breakdown (Max): 100 V minimum
Current - Collector (Ic) (Max): 8 A or greater
Package / Case: TO-220-3
Mounting Type: Through Hole

Secondary Compatibility Factors:

Operating Temperature Range: -65°C to 150°C preferred for full compatibility
Vce Saturation characteristics within acceptable switching performance
DC Current Gain (hFE) sufficient for intended circuit operation

Substitute parts are grouped into three categories based on current rating alignment:

Category A - Direct Current Rating Match (8 A): Parts with 8 A maximum collector current provide direct functional equivalence.

Category B - Higher Current Rating (≥8 A): Parts rated above 8 A offer enhanced current handling capability and are suitable for applications requiring design margin or future uprating.

Category C - Lower Current Rating (<8 A): Parts rated below 8 A are listed for reference but require circuit redesign validation to confirm adequate current capacity.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) [A]	Vce(br)max [V]	Power [W]	Vce Sat [V]	hFE (Min)	Temp Range [°C]	Status
BD543C-S	Bourns Inc.	8	100	2	1.0 @ 1.6A, 8A	15 @ 5A, 4V	-65 to 150	Obsolete
BD239C	STMicroelectronics	2	100	2	0.7 @ 0.2A, 1A	15 @ 1A, 4V	-65 to 150	Active
BD241C	STMicroelectronics	3	100	40	1.2 @ 0.6A, 3A	10 @ 3A, 4V	-65 to 150	Active
BD243CG	onsemi	6	100	65	1.5 @ 1A, 6A	15 @ 3A, 4V	-65 to 150	Active
BD911	NTE Electronics, Inc	15	100	90	3.0 @ 2.5A, 10A	40 @ 0.5A, 4V	-65 to 150	Active
KSC2334Y	Fairchild Semiconductor	7	100	1.5	0.6 @ 0.5A, 5A	120 @ 3A, 5V	-65 to 150	Active
KSC2334YTU	onsemi	7	100	1.5	0.6 @ 0.5A, 5A	120 @ 3A, 5V	-65 to 150	Active
MJE15028G	onsemi	8	120	50	0.5 @ 0.1A, 1A	20 @ 4A, 2V	-65 to 150	Active
TIP29C	NTE Electronics, Inc	1	100	2	0.7 @ 0.125A, 1A	15 @ 1A, 4V	-65 to 150	Active
TIP29CG	onsemi	1	100	2	0.7 @ 0.125A, 1A	15 @ 1A, 4V	-65 to 150	Active
TIP31C	Fairchild Semiconductor	3	100	40	1.2 @ 0.375A, 3A	10 @ 3A, 4V	-65 to 150	Active

Engineering Selection Recommendations

Direct Substitutes (Recommended Priority):

The MJE15028G offers the closest functional match to the BD543C-S. It maintains the 8 A collector current rating, 100 V+ breakdown voltage specification, and full -65°C to 150°C operating temperature range. The MJE15028G is manufactured by onsemi with active product status and ROHS3 compliance. The elevated power rating (50 W vs. 2 W) and improved thermal characteristics provide design margin for thermal management.

Higher Current Capacity Alternatives:

The BD911 provides 15 A maximum collector current with 100 V breakdown voltage and active product status. This part accommodates applications requiring increased current headroom. However, the elevated Vce saturation voltage (3.0 V) and RoHS non-compliance status require circuit validation before selection.

Near-Equivalent Current Rating Options:

The BD243CG and KSC2334Y/KSC2334YTU devices provide 6 A and 7 A maximum collector current respectively, approaching the BD543C-S specification. Both maintain 100 V breakdown voltage and full temperature range operation. The KSC2334 variants offer superior DC current gain (120 vs. 15), which may reduce base drive requirements in switching applications.

Lower Current Rating Parts (Limited Substitution):

The BD239C, BD241C, TIP29C, TIP29CG, and TIP31C are listed with collector current ratings below 8 A. These parts are suitable only for applications where the circuit design can accommodate reduced current capacity or where the original design included safety margin above the 8 A specification.

Compliance and Availability:

All recommended substitutes maintain ROHS3 compliance except BD911. All active-status parts are currently in production with documented inventory availability. The BD543C-S obsolete status necessitates transition to one of these active alternatives for new production and long-term supply assurance.

Frequently Asked Questions (FAQ)

Q: Can the MJE15028G directly replace the BD543C-S in all applications?

A: The MJE15028G matches the critical electrical parameters: 8 A collector current, 100 V+ breakdown voltage, TO-220-3 package, and -65°C to 150°C operating range. The higher power rating (50 W) and improved saturation characteristics provide enhanced performance. Mechanical fit and pinout are identical. Verification of thermal management is recommended due to the increased power dissipation capability.

Q: What is the difference between KSC2334Y and KSC2334YTU?

A: Both parts are electrically identical NPN transistors with 7 A maximum collector current and 100 V breakdown voltage. The primary difference is packaging: KSC2334Y is supplied in bulk, while KSC2334YTU is supplied in tube format. Both are manufactured to the same electrical specifications and are suitable for the same applications.

Q: Why is the BD911 listed if it has higher Vce saturation voltage?

A: The BD911 meets the core substitution criteria: NPN type, 100 V breakdown voltage, TO-220-3 package, and exceeds the 8 A current requirement with 15 A rating. The elevated Vce saturation (3.0 V vs. 1.0 V) affects switching loss and heat dissipation. Applications with low-impedance loads or high switching frequency require circuit analysis to confirm acceptable performance.

Q: Are parts with lower current ratings (TIP29C, BD239C) suitable substitutes?

A: Parts rated below 8 A are not direct substitutes for the BD543C-S. They are listed for reference in applications where the original design included current margin or where circuit redesign is acceptable. The TIP29C and BD239C are limited to 1 A and 2 A respectively, requiring significant circuit modification.

Q: What is the significance of the operating temperature range in substitution?

A: The BD543C-S specifies -65°C to 150°C operation. All recommended substitutes maintain this full range, ensuring compatibility in temperature-critical applications. Parts with reduced temperature ranges (such as those limited to -40°C or 0°C minimum) are not suitable for low-temperature operation without circuit redesign.

Q: Does package type affect substitution compatibility?

A: All listed substitutes use the TO-220-3 through-hole package, ensuring mechanical and electrical pin compatibility. Packaging format (tube, bulk, bag) affects handling and storage but does not impact electrical substitution. The TO-220-3 case outline is standardized across all parts.

Q: What compliance certifications should be verified for new designs?

A: All recommended active-status substitutes maintain ROHS3 compliance, suitable for applications subject to RoHS Directive requirements. The BD911 is RoHS non-compliant and requires compliance verification before selection in regulated applications. REACH status is documented for each part where applicable.

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