BD243CTU Equivalent & Substitute Parts

Part Overview

The BD243CTU is an NPN bipolar junction transistor manufactured by onsemi, rated for 100 V collector-emitter breakdown voltage and 6 A maximum collector current in a TO-220-3 through-hole package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The BD243CTU delivers 65 W maximum power dissipation and operates at junction temperatures up to 150°C.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	100	V
Current - Collector (Ic) (Max)	6	A
Power - Max	65	W
Vce Saturation (Max) @ Ib, Ic	1.5V @ 1A, 6A	V
Current - Collector Cutoff (Max)	700	µA
DC Current Gain (hFE) (Min) @ Ic, Vce	15 @ 3A, 4V	—
Operating Temperature (Max)	150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-220-3	—

Substitute Part Grouping Explanation

Substitution of the BD243CTU is determined by strict equivalence across the following electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN
Voltage - Collector Emitter Breakdown (Max): 100 V minimum
Current - Collector (Ic) (Max): 6 A minimum
Package / Case: TO-220-3 compatible
Mounting Type: Through Hole

Substitution Categories:

Direct Equivalents maintain all primary electrical parameters (100 V, 6 A) and identical package specifications. These parts are pin-compatible and functionally interchangeable without circuit modification.

Similar Parts share the same voltage rating (100 V) and package type (TO-220-3) but differ in maximum collector current or power dissipation. These parts are suitable for applications where the lower current or power rating is acceptable.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) [A]	Vce Breakdown (Max) [V]	Power (Max) [W]	Vce Sat @ Ib, Ic	Package	Frequency - Transition
BD243CTU	onsemi	Obsolete	6	100	65	1.5V @ 1A, 6A	TO-220-3	—
BD243CG	onsemi	Active	6	100	65	1.5V @ 1A, 6A	TO-220-3	3MHz
TIP41CG	onsemi	Active	6	100	2	1.5V @ 600mA, 6A	TO-220-3	3MHz
TIP41C	NTE Electronics, Inc	Active	6	100	2	1.5V @ 600mA, 6A	TO-220-3	3MHz
TIP41C-BP	Micro Commercial Co	Active	6	100	2	1.5V @ 600mA, 6A	TO-220-3	3MHz
TIP29CG	onsemi	Active	1	100	2	700mV @ 125mA, 1A	TO-220-3	3MHz
TIP31CG	onsemi	Active	3	100	2	1.2V @ 375mA, 3A	TO-220-3	3MHz
BD911	NTE Electronics, Inc	Active	15	100	90	3V @ 2.5A, 10A	TO-220-3	3MHz

Engineering Selection Recommendations

Direct Replacement (Recommended for Obsolescence Mitigation):

BD243CG is the primary direct equivalent to BD243CTU. Both parts are manufactured by onsemi, share identical electrical specifications (100 V, 6 A, 65 W), and use the TO-220-3 package. BD243CG holds Active product status and is RoHS3 compliant, providing long-term availability and regulatory compliance advantages over the obsolete BD243CTU.

Functional Equivalents (6 A Rating):

TIP41CG, TIP41C, and TIP41C-BP maintain the 6 A collector current and 100 V voltage rating required for direct electrical substitution. These parts are manufactured by onsemi, NTE Electronics, and Micro Commercial Co respectively, all with Active product status. Power dissipation is reduced to 2 W compared to the BD243CTU's 65 W rating; this reduction is acceptable in applications where thermal design does not depend on the higher power capability. All three parts are RoHS3 compliant.

Current-Limited Alternatives (Lower Current Ratings):

TIP29CG (1 A) and TIP31CG (3 A) share the 100 V voltage rating and TO-220-3 package but provide reduced collector current capacity. These parts are suitable only for applications where the lower current rating meets circuit requirements.

Higher Current Alternative:

BD911 provides 15 A collector current and 90 W power dissipation, exceeding the BD243CTU specifications. This part is suitable for applications requiring higher current handling or thermal performance. BD911 is manufactured by NTE Electronics with Active product status but is RoHS non-compliant.

Frequently Asked Questions (FAQ)

Q: Can BD243CG directly replace BD243CTU without circuit modification?

A: Yes. BD243CG is a direct equivalent manufactured by onsemi with identical electrical parameters (100 V, 6 A, 65 W) and the same TO-220-3 package. Pin configuration and functional characteristics are identical. The primary difference is product status: BD243CG is Active while BD243CTU is Obsolete.

Q: What is the difference between BD243CG and TIP41CG?

A: Both parts share 100 V voltage rating, 6 A collector current, and TO-220-3 package. The key difference is maximum power dissipation: BD243CG is rated for 65 W while TIP41CG is rated for 2 W. In applications where power dissipation does not exceed 2 W, TIP41CG is functionally equivalent. In high-power applications, BD243CG is the appropriate choice.

Q: Are TIP41C and TIP41CG interchangeable?

A: TIP41C (NTE Electronics) and TIP41CG (onsemi) share identical electrical specifications and TO-220-3 package configuration. The primary difference is manufacturer and packaging format: TIP41C is supplied in Bag packaging while TIP41CG is supplied in Tube packaging. Both are Active products and RoHS3 compliant.

Q: Can TIP29CG or TIP31CG replace BD243CTU?

A: TIP29CG and TIP31CG are not direct replacements. TIP29CG is limited to 1 A collector current and TIP31CG to 3 A, both below the BD243CTU's 6 A rating. These parts are suitable only for applications where the lower current rating is acceptable and the circuit design does not require 6 A capability.

Q: Is BD911 a suitable replacement for BD243CTU?

A: BD911 exceeds BD243CTU specifications with 15 A collector current and 90 W power dissipation. It is suitable for applications requiring higher current or power handling. However, BD911 is RoHS non-compliant, which may restrict use in regulated applications. Electrical substitution is feasible but requires verification that the higher specifications do not introduce design complications.

Q: What is the significance of the TO-220-3 package designation?

A: TO-220-3 specifies a three-lead through-hole package with standardized pin spacing and mounting configuration. All listed substitute parts use TO-220-3 or compatible variants (TO-220, TO-220AB), ensuring mechanical compatibility with existing PCB layouts and heat sink mounting arrangements.

Q: Why does BD243CTU show no transition frequency while other parts specify 3 MHz?

A: The BD243CTU datasheet does not provide transition frequency specification. Substitute parts including BD243CG, TIP41CG, TIP41C, TIP41C-BP, TIP29CG, TIP31CG, and BD911 all specify 3 MHz transition frequency. This parameter indicates switching speed capability; the absence of specification in BD243CTU does not indicate incompatibility with the specified substitutes.

Q: What compliance certifications should I verify for new designs?

A: For new designs, RoHS3 compliance is the primary regulatory requirement. BD243CG, TIP41CG, TIP41C, TIP41C-BP, TIP29CG, and TIP31CG are all RoHS3 compliant. BD911 is RoHS non-compliant and should be avoided in applications subject to RoHS regulations. All listed parts are REACH Unaffected or REACH compliant.

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