BD540A-S Equivalent & Substitute Parts Reference

Part Overview

The BD540A-S, manufactured by Bourns Inc., is a PNP Bipolar Junction Transistor (BJT) rated for 60 V collector-emitter breakdown and 5 A maximum collector current, provided in a TO-220-3 through-hole package. It is classified as obsolete, making it necessary to consider equivalent or substitute transistors for maintenance, repair, or new designs that require continuity of performance and fit. Alternative models must match essential electrical, thermal, and mechanical parameters to ensure form, fit, and function equivalence.

Key Parameters

Parameter	BD540A-S
Transistor Type	PNP
Voltage - Collector Emitter Breakdown (Max)	60 V
Current - Collector (Ic) (Max)	5 A
Vce Saturation (Max) @ Ib, Ic	1.5V @ 1A, 5A
Current - Collector Cutoff (Max)	300µA
DC Current Gain (hFE) (Min) @ Ic, Vce	12 @ 3A, 4V
Power - Max	2 W
Mounting Type	Through Hole
Package / Case	TO-220-3
Supplier Device Package	TO-220
Operating Temperature	-65°C ~ 150°C (TJ)
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the BD540A-S are identified strictly based on matching or exceeding the following key electrical and mechanical parameters:

Transistor type (PNP)
Collector-emitter breakdown voltage (Vce) minimum 60 V
Maximum collector current (Ic) at least 5 A
Power dissipation capability (≥2 W)
Package and mounting compatibility (TO-220-3, through-hole)
Operational temperature range suitable for the same applications
Similar device package for physical interchangeability

All listed substitutes are within the transistors, bipolar (BJT) category and maintain mechanical compatibility with TO-220-3 through-hole mounting.

Parameter Comparison

Parameter	BD540A-S	TIP42A	TIP42AG	MJE2955T	MJE2955TG
Transistor Type	PNP	PNP	PNP	PNP	PNP
Voltage - Collector Emitter Breakdown (Max)	60 V	60 V	60 V	60 V	60 V
Current - Collector (Ic) (Max)	5 A	6 A	6 A	10 A	10 A
Vce Saturation (Max) @ Ib, Ic	1.5V @ 1A, 5A	1.5V @ 600mA, 6A	1.5V @ 600mA, 6A	8V @ 3.3A, 10A	8V @ 3.3A, 10A
Current - Collector Cutoff (Max)	300µA	700µA	700µA	700µA	700µA
DC Current Gain (hFE) (Min) @ Ic, Vce	12 @ 3A, 4V	15 @ 3A, 4V	15 @ 3A, 4V	20 @ 4A, 4V	20 @ 4A, 4V
Power - Max	2 W	2 W	2 W	75 W	75 W
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3
Operating Temperature	-65°C ~ 150°C (TJ)	150°C (TJ)	-65°C ~ 150°C (TJ)	-55°C ~ 150°C (TJ)	-55°C ~ 150°C (TJ)
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

Selection between listed substitute parts should account for the product status (the BD540A-S is obsolete, alternatives are active), and environmental compliance requirements such as RoHS. For applications that require RoHS3 compliance, TIP42AG and MJE2955TG are appropriate choices, while TIP42A and MJE2955T are not RoHS compliant. All substitutes ensure package and electrical compatibility based on provided parameters.

Frequently Asked Questions (FAQ)

Q1: What are the most critical parameters when choosing a substitute for the BD540A-S?
A1: The most critical parameters are transistor type (PNP), collector-emitter breakdown voltage (minimum 60 V), maximum collector current (minimum 5 A), package/case (TO-220-3), mounting type (through-hole), and power dissipation.

Q2: Are all substitute transistors physically interchangeable with the BD540A-S?
A2: All listed substitute parts use the TO-220-3 through-hole package ensuring mechanical interchangeability.

Q3: Are the substitute parts RoHS compliant?
A3: Only TIP42AG and MJE2955TG are ROHS3 compliant, matching the compliance status of the original BD540A-S. TIP42A and MJE2955T are not RoHS compliant.

Q4: Is there a difference in electrical performance among these substitute parts?
A4: All substitutes meet or exceed the key electrical parameters (such as voltage, current, and power), though some provide higher current or gain.

Q5: Can the substitute parts be used without modification to the board layout?
A5: All specified substitutes are in TO-220-3 packages for through-hole mounting, providing direct fit compatibility with footprints designed for the BD540A-S.

Q6: Why is it necessary to select an active or RoHS compliant substitute?
A6: The BD540A-S is obsolete and may not be available for purchase; RoHS compliance may be required for regulatory or environmental reasons in certain applications.

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