2SA1943 bipolar transistor — Specifications & Equivalents

About the 2SA1943

The 2SA1943 is a PNP bipolar transistor with a collector–emitter voltage (V_CEO) rating of 250 V, a continuous collector current (I_C) of 17 A and a DC current gain (h_FE) of minimum 55. It can dissipate up to 150 W. It is supplied in the TO264 package.

At a glance

• Type: PNP bipolar transistor
• Max collector–emitter voltage (V_CEO): 250 V
• Max collector current (I_C): 17 A
• DC current gain (h_FE): minimum 55
• Power dissipation (P_D): 150 W
• Package: TO264
• Manufacturer: Multi-source (JIS registered part number)

Typical applications

Judging from its ratings the 2SA1943 is generally applied in power output and driver stages.

The quoted current gain of minimum 55 determines the base drive needed: divide your target collector current by the minimum h_FE, not the typical figure, when sizing the base resistor.

Biasing and absolute maximum ratings

Absolute-maximum breakdown limits are V_CEO 250 V, V_CBO 250 V and V_EBO 5 V (magnitudes). The emitter–base rating is the easiest to overlook and is often only a few volts, so protect the junction against reverse drive.

Dissipation is capped at 150 W, and that figure assumes the datasheet's mounting and ambient conditions — derate it for your own thermal design.

Choosing a replacement for the 2SA1943

A drop-in substitute for the 2SA1943 must be the same PNP type and offer a collector–emitter rating of at least 250 V, a collector current rating of at least 17 A and current gain in the same ballpark as minimum 55.

Mechanically, check the replacement against the TO264 footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.

Because 2SA1943 is a JIS-registered part number rather than one vendor's proprietary series, it is produced by several manufacturers. Datasheet figures vary slightly between them, so check the datasheet of the brand you actually buy — this also makes like-for-like sourcing easier.

Where the application switches inductive loads or runs near the voltage limit, keep extra headroom rather than choosing a part that only just meets the original numbers.

Frequently asked questions

What is the 2SA1943?

The 2SA1943 is a PNP bipolar junction transistor (BJT). It is rated for 250 V collector-emitter and 17 A continuous collector current.

What is the maximum voltage of the 2SA1943?

Maximum collector-emitter voltage (Vceo) is 250 V, and collector-base (Vcbo) is 250 V.

How much current can the 2SA1943 handle?

Continuous collector current is rated at 17 A, with dissipation limited to 150 W.

What is the hFE of the 2SA1943?

DC current gain (hFE) is quoted as minimum 55. Size base drive from the minimum value so the transistor saturates fully across production spread.

What package does the 2SA1943 come in?

It is listed in TO264. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the 2SA1943?

This page lists 17 candidate equivalents matched on electrical ratings and package. Any replacement should meet or exceed the original voltage, current and dissipation figures and use a compatible drive level.