BD243B-S Equivalent & Substitute Parts Engineering Reference

Part Overview

The BD243B-S is an NPN bipolar junction transistor (BJT) manufactured by Bourns Inc. in a TO-220 package, designed for through-hole mounting. It is rated for a collector-emitter voltage of 80 V, a continuous collector current of 6 A, and maximum power dissipation of 2 W. The product series is obsolete, making it necessary to evaluate alternative transistors with compatible electrical and package parameters. Reliable substitution is critical for maintaining function and compliance in existing designs that specify the BD243B-S.

Key Parameters

Parameter	BD243B-S Value
Transistor Type	NPN
Current - Collector (Ic) (Max)	6 A
Voltage - Collector Emitter Breakdown (Max)	80 V
Vce Saturation (Max) @ Ib, Ic	1.5V @ 1A, 6A
Current - Collector Cutoff (Max)	700µA
DC Current Gain (hFE) (Min) @ Ic, Vce	15 @ 3A, 4V
Power - Max	2 W
Operating Temperature	-65°C ~ 150°C (TJ)
Mounting Type	Through Hole
Package / Case	TO-220-3
Supplier Device Package	TO-220
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
ECCN	EAR99
HTSUS	8541.29.0095

Substitute Part Grouping Explanation

Substitute parts for the BD243B-S are selected strictly based on direct parameter equivalence. Key substitution parameters include transistor type (NPN), maximum collector current (Ic), collector-emitter breakdown voltage, saturation voltage (Vce(sat)) at specified collector and base currents, cutoff current, minimum DC current gain (hFE), maximum power, operating temperature range, package type (TO-220-3), through-hole mounting, RoHS compliance, and matching or broader regulatory compliance (ECCN/HTSUS). Substitute and similar parts are grouped when they meet these specified parameters.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Transistor Type	Current - Collector (Ic) (Max)	Voltage - Collector Emitter Breakdown (Max)	Vce Saturation (Max) @ Ib, Ic	Current - Collector Cutoff (Max)	DC Current Gain (hFE) (Min) @ Ic, Vce	Power - Max	Operating Temperature	Mounting Type	Package / Case	Supplier Device Package	RoHS Status	MSL	ECCN	HTSUS	Product Status
BD243B-S	Bourns Inc.	NPN	6 A	80 V	1.5V @ 1A, 6A	700µA	15 @ 3A, 4V	2 W	-65°C ~ 150°C (TJ)	Through Hole	TO-220-3	TO-220	ROHS3 Compliant	1 (Unlimited)	EAR99	8541.29.0095	Obsolete
TIP41BG	onsemi	NPN	6 A	80 V	1.5V @ 600mA, 6A	700µA	15 @ 3A, 4V	2 W	-65°C ~ 150°C (TJ)	Through Hole	TO-220-3	TO-220	ROHS3 Compliant	Not Applicable	EAR99	8541.29.0095	Active
2N6488G	onsemi	NPN	15 A	80 V	3.5V @ 5A, 15A	1mA	20 @ 5A, 4V	1.8 W	-65°C ~ 150°C (TJ)	Through Hole	TO-220-3	TO-220	ROHS3 Compliant	Not Applicable	EAR99	8541.29.0095	Active
D44H11	Solid State Inc.	NPN	-	-	-	-	-	-	-	Through Hole	TO-220-3	TO-220	ROHS3 Compliant	1 (Unlimited)	EAR99	8541.10.0080	Active
TIP29BG	onsemi	NPN	1 A	80 V	700mV @ 125mA, 1A	300µA	15 @ 1A, 4V	2 W	-65°C ~ 150°C (TJ)	Through Hole	TO-220-3	TO-220	ROHS3 Compliant	Not Applicable	EAR99	8541.29.0095	Active
TIP31BG	onsemi	NPN	3 A	80 V	1.2V @ 375mA, 3A	300µA	10 @ 3A, 4V	2 W	-65°C ~ 150°C (TJ)	Through Hole	TO-220-3	TO-220	ROHS3 Compliant	Not Applicable	EAR99	8541.29.0095	Active
TIP41AG	onsemi	NPN	6 A	60 V	1.5V @ 600mA, 6A	700µA	15 @ 3A, 4V	2 W	-65°C ~ 150°C (TJ)	Through Hole	TO-220-3	TO-220	ROHS3 Compliant	Not Applicable	EAR99	8541.29.0095	Last Time Buy

Engineering Selection Recommendations

Selection should be based on the product lifecycle status. BD243B-S is obsolete; suitable alternatives such as TIP41BG, TIP41AG, 2N6488G, TIP31BG, TIP29BG, and D44H11 are active or last time buy. All listed substitutes are ROHS3 compliant and classified under ECCN EAR99. All alternatives are through-hole, TO-220 package types, supporting mechanical interchangeability and compliance requirements.

Frequently Asked Questions (FAQ)

Q1: What are the most critical parameters for selecting a BD243B-S equivalent?
A1: NPN type, collector current rating (≥6 A for direct substitutes), collector-emitter voltage (80 V), matching power dissipation (2 W), package/case (TO-220-3), and RoHS compliance.

Q2: Are package and mounting type important for substitution?
A2: Yes, all substitutes must be through-hole devices in a TO-220-3 / TO-220 package to maintain mechanical compatibility.

Q3: How does product status affect substitute selection?
A3: Only active or last time buy substitutes should be used in new designs. BD243B-S is obsolete; active substitutes such as TIP41BG should be prioritized.

Q4: Are higher-current or higher-voltage ratings acceptable?
A4: Substitutes with equal or greater current or voltage ratings, if documented, fit parameter equivalency.

Q5: Are all substitute parts RoHS compliant?
A5: All listed substitutes are RoHS3 compliant as per provided parameters.

Q6: Can substitutes with different hFE or Vce(sat) values be used?
A6: Only values meeting or exceeding the minimum gain and maximum saturation voltage as specified qualify for direct substitution.

Q7: Are regulatory codes (ECCN/HTSUS) matched?
A7: All substitutes except D44H11 share the main part’s ECCN and HTSUS. D44H11 uses a distinct HTSUS code per provided data.

Q8: Is there any difference in moisture sensitivity level (MSL)?
A8: Main part MSL is 1 (unlimited); several substitutes list "Not Applicable," appropriate for through-hole, non-reflow applications.

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