BD243A-S Equivalent & Substitute Parts Engineering Reference

Part Overview

The BD243A-S (Bourns Inc.) is a Bipolar (BJT) NPN transistor featuring 60V collector-emitter breakdown voltage and 6A maximum collector current in a standard TO-220 through-hole package. It is classified as obsolete, necessitating the identification of substitute or equivalent transistors for ongoing designs and maintenance. Selecting suitable alternatives ensures compatibility with existing footprints, electrical specifications, and compliance requirements.

Key Parameters

Manufacturer Part Number	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	Package / Case	Mounting Type	RoHS Status	Product Status
BD243A-S	NPN	6 A	60 V	1.5V @ 1A, 6A	700µA	15 @ 3A, 4V	2 W	-65°C ~ 150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Obsolete

Substitute Part Grouping Explanation

Substitution for BD243A-S is determined strictly according to the following key parameters: Transistor Type, Maximum Collector Current (Ic), Maximum Collector-Emitter Breakdown Voltage (Vce), Maximum Vce Saturation, Maximum Collector Cutoff Current, Minimum DC Current Gain (hFE), Maximum Power Dissipation, Operating Temperature Range, Package/Case, and RoHS Compliance. Candidates must match or exceed critical electrical and mechanical specifications as outlined in the part input, and maintain compatible package mounting for direct PCB replacement.

Parameter Comparison

Manufacturer Part Number	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	Package / Case	Mounting Type	RoHS Status	Product Status
BD243A-S	NPN	6 A	60 V	1.5V @ 1A, 6A	700µA	15 @ 3A, 4V	2 W	-65°C ~ 150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Obsolete
TIP41AG	NPN	6 A	60 V	1.5V @ 600mA, 6A	700µA	15 @ 3A, 4V	2 W	-65°C ~ 150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Last Time Buy
D44H8	NPN	10 A	60 V	1V @ 400mA, 8A	10µA	40 @ 4A, 1V	50 W	150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Active
2ST31A	NPN	3 A	60 V	1.2V @ 375mA, 3A	300µA	100 @ 20mA, 4V	40 W	150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Active
MJE3055T	NPN	10 A	60 V	8V @ 3.3A, 10A	700µA	20 @ 4A, 4V	75 W	-55°C ~ 150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Active
MJE3055TG	NPN	10 A	60 V	8V @ 3.3A, 10A	700µA	20 @ 4A, 4V	75 W	-55°C ~ 150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Active
TIP29AG	NPN	1 A	60 V	700mV @ 125mA, 1A	300µA	15 @ 1A, 4V	2 W	-65°C ~ 150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Active
TIP31A	NPN	3 A	60 V	1.2V @ 375mA, 3A	300µA	25 @ 1A, 4V	40 W	-65°C ~ 150°C (TJ)	TO-220-3	Through Hole	ROHS3 Compliant	Active

Engineering Selection Recommendations

For replacement of the obsolete BD243A-S, selection must be based on equivalent or improved collector current and voltage ratings, TO-220-3 package compatibility, and matching NPN transistor polarity. All substitute parts listed are ROHS3 compliant. Substitute parts with 'Active' or 'Last Time Buy' status are suitable for ongoing or new designs where compliance and long-term sourcing are required.

Frequently Asked Questions (FAQ)

Q1: Which key parameters must match for a substitute BJT transistor in TO-220 package?
A1: Transistor Type, Maximum Collector Current (Ic), Maximum Collector-Emitter Breakdown Voltage (Vce), Maximum Vce Saturation, Collector Cutoff Current, Minimum DC Current Gain (hFE), Power Dissipation, Operating Temperature Range, Package/Case, and Compliance status must be identical or superior.

Q2: Are all substitutes provided in a TO-220-3 package for direct PCB compatibility?
A2: All listed substitute part numbers are supplied in the TO-220-3 package and are suitable for through-hole mounting.

Q3: Should RoHS compliance be considered when selecting substitutes?
A3: RoHS compliance is necessary when required by regulatory or facility mandates; all substitutes listed are ROHS3 compliant.

Q4: What is the significance of 'Product Status' in part selection?
A4: 'Product Status' denotes ongoing availablility. Only 'Active' or 'Last Time Buy' substitutes are suitable for sustainable sourcing and current industry practices.

Q5: Can substitute parts with differing collector current or power ratings be used?
A5: Substitutes must meet or exceed the application’s minimum electrical requirements. Selection should be made based solely on the parameters explicitly provided.

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