2SD720 bipolar transistor — Specifications & Equivalents

About the 2SD720

The 2SD720 is an NPN bipolar transistor with a collector–emitter voltage (V_CEO) rating of 400 V, a continuous collector current (I_C) of 7 A and a DC current gain (h_FE) of minimum 400. It can dissipate up to 100 W and is rated to a junction temperature of 135 °C. It is supplied in the TO3 package.

At a glance

• Type: NPN bipolar transistor
• Max collector–emitter voltage (V_CEO): 400 V
• Max collector current (I_C): 7 A
• DC current gain (h_FE): minimum 400
• Power dissipation (P_D): 100 W
• Max junction temperature (T_J): 135 °C
• Package: TO3
• Manufacturer: Multi-source (JIS registered part number)

Typical applications

Judging from its ratings the 2SD720 is generally applied in power output and driver stages and high-voltage switching such as offline converters and lamp drivers.

The quoted current gain of minimum 400 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 400 V, V_CBO 400 V and V_EBO 10 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 100 W, and that figure assumes the datasheet's mounting and ambient conditions — derate it for your own thermal design.

Choosing a replacement for the 2SD720

A drop-in substitute for the 2SD720 must be the same NPN type and offer a collector–emitter rating of at least 400 V, a collector current rating of at least 7 A and current gain in the same ballpark as minimum 400.

Mechanically, check the replacement against the TO3 footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.

Because 2SD720 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 2SD720?

The 2SD720 is an NPN bipolar junction transistor (BJT). It is rated for 400 V collector-emitter and 7 A continuous collector current.

What is the maximum voltage of the 2SD720?

Maximum collector-emitter voltage (Vceo) is 400 V, and collector-base (Vcbo) is 400 V.

How much current can the 2SD720 handle?

Continuous collector current is rated at 7 A, with dissipation limited to 100 W.

What is the hFE of the 2SD720?

DC current gain (hFE) is quoted as minimum 400. Size base drive from the minimum value so the transistor saturates fully across production spread.

What package does the 2SD720 come in?

It is listed in TO3. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the 2SD720?

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.