2SA1943RTU Equivalent & Substitute Parts

Part Overview

The 2SA1943RTU is an obsolete PNP bipolar junction transistor manufactured by onsemi, rated for 250 V collector-emitter breakdown voltage and 17 A maximum collector current. This device is packaged in TO-264-3 configuration for through-hole mounting applications requiring high-current switching or amplification in power electronics circuits. Due to its obsolete product status, equivalent and substitute parts are necessary for design continuity and procurement of new inventory.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	250	V
Current - Collector (Ic) (Max)	17	A
Power - Max	150	W
Frequency - Transition	30	MHz
Operating Temperature Range	-50 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-264-3	—

Substitute Part Grouping Explanation

Substitution of the 2SA1943RTU is determined by the following critical parameters: transistor type (PNP), collector-emitter breakdown voltage rating, maximum collector current capacity, power dissipation capability, transition frequency, and mounting configuration. Substitute parts must maintain electrical compatibility within the specified operating ranges while meeting the through-hole mounting requirement.

The substitute parts are grouped into two categories:

Manufacturer Recommended Equivalent: Parts that share identical electrical specifications and packaging with the main part, differing only in product status or packaging format.

Similar Substitute Parts: Parts that maintain functional compatibility through equivalent or superior electrical ratings, though with variations in specific parameters such as voltage rating, current capacity, or package type.

Parameter Comparison

Parameter	2SA1943RTU	2SA1943OTU	MJL1302AG	2SA1943-O(Q)
Manufacturer	onsemi	onsemi	onsemi	Toshiba Semiconductor and Storage
Product Status	Obsolete	Active	Active	Active
Transistor Type	PNP	PNP	PNP	PNP
Voltage - Collector Emitter Breakdown (Max)	250 V	250 V	260 V	230 V
Current - Collector (Ic) (Max)	17 A	17 A	15 A	15 A
Vce Saturation (Max) @ Ib, Ic	3V @ 800mA, 8A	3V @ 800mA, 8A	3V @ 1A, 10A	3V @ 800mA, 8A
Current - Collector Cutoff (Max)	5µA	5µA	50µA	5µA
DC Current Gain (hFE) (Min) @ Ic, Vce	55 @ 1A, 5V	80 @ 1A, 5V	75 @ 5A, 5V	80 @ 1A, 5V
Power - Max	150 W	150 W	200 W	150 W
Frequency - Transition	30 MHz	30 MHz	30 MHz	30 MHz
Operating Temperature Range	-50 to 150°C	-50 to 150°C	-65 to 150°C	—
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-264-3	TO-264-3	TO-264	TO-3P(L)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

2SA1943OTU (Manufacturer Recommended Equivalent): This part is the direct active equivalent to the 2SA1943RTU. It maintains identical electrical specifications, voltage rating, current capacity, power dissipation, and TO-264-3 packaging. The primary distinction is active product status and tube packaging format. This part is the preferred replacement for obsolete 2SA1943RTU inventory.

MJL1302AG (Similar Substitute): This part provides superior voltage rating (260 V versus 250 V) and increased power dissipation capability (200 W versus 150 W). However, maximum collector current is reduced to 15 A compared to 17 A. The collector cutoff current is higher at 50µA. This part is suitable for applications where the 17 A current requirement can be accommodated within the 15 A rating, or where the enhanced voltage and power ratings provide design margin. Package compatibility is maintained through TO-264 configuration.

2SA1943-O(Q) (Similar Substitute): This Toshiba-manufactured part maintains identical saturation voltage and current gain characteristics. Voltage rating is reduced to 230 V, and maximum collector current is 15 A. The TO-3P(L) package differs from the TO-264-3 configuration, requiring board layout and thermal management evaluation. This part is suitable for applications with lower voltage requirements and where package transition is feasible.

All substitute parts maintain ROHS3 compliance and through-hole mounting capability. Selection should be based on specific application voltage and current requirements, thermal management constraints, and package compatibility with existing board designs.

Frequently Asked Questions (FAQ)

Q: Can 2SA1943OTU directly replace 2SA1943RTU without circuit modification?

A: Yes. The 2SA1943OTU maintains identical electrical specifications, voltage rating, current capacity, power dissipation, and package configuration. Direct substitution is supported without circuit modification.

Q: What are the limitations of using MJL1302AG as a substitute?

A: The MJL1302AG has a maximum collector current rating of 15 A compared to the 2SA1943RTU's 17 A. Applications requiring the full 17 A capability must verify operation within the 15 A limit. The collector cutoff current is also higher at 50µA. Voltage rating and power dissipation are superior, providing design margin in those parameters.

Q: Is the 2SA1943-O(Q) package compatible with existing PCB designs?

A: The 2SA1943-O(Q) uses TO-3P(L) packaging, which differs from the TO-264-3 package of the 2SA1943RTU. Board layout, mounting hole spacing, and thermal management must be re-evaluated for this package transition. Direct mechanical substitution is not possible without PCB modification.

Q: What is the significance of the DC current gain difference between substitute parts?

A: The 2SA1943RTU specifies minimum hFE of 55 at 1A, 5V. The 2SA1943OTU and 2SA1943-O(Q) specify minimum hFE of 80 at the same conditions, indicating improved current gain. The MJL1302AG specifies hFE of 75 at 5A, 5V, measured at higher collector current. Higher current gain provides improved switching efficiency and reduced base drive requirements.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance status, consistent with the original 2SA1943RTU specification.

Q: What thermal considerations apply when substituting packages?

A: The TO-264-3 and TO-264 packages share similar thermal characteristics. The TO-3P(L) package has different thermal resistance and mounting geometry. Applications requiring thermal analysis must account for package-specific thermal resistance values when transitioning to the 2SA1943-O(Q).

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