BLD128D Datasheet – 400V, 5A, NPN Transistor, TO-220

This post explains for the transistor.

The Part Number is BLD128D.

The function of this semiconductor is 400V, 5A, NPN Transistor.

The package is TO-220 Type

Manufacturer: SI Semiconductors


BLD128D datasheet pdf


The BLD128D is 400V, 5A, Silicon NPN transistor in a TO-220 Plastic Package.

A NPN transistor is a type of bipolar junction transistor (BJT) that consists of two n-type semiconductor materials separated by a single p-type material.

The NPN transistor is used to amplify or switch electronic signals and is widely used in many electronic circuits. It works by controlling the current flow between the collector and emitter terminals through the base terminal.


1. High voltage capability

2. High speed switching

3. Wide SOA,ROHS compliant


Absolute maximum ratings ( Ta=25°C )

1. Collector to Base Voltage: Vcbo = 700 V

2. Collector to Emitter Voltage: Vceo = 400 V

3. Emitter to Base Voltage: Vebo = 9 V

4. Collector Current: Ic = 5 A

5. Collector Dissipation : Pc = 2W

6. Junction Temperature: Tj = 150°C

7. Storage Temperature: Tsg = -55 ~ +150°C



1. Fluorescent lamp, electronics ballast,

2. Electronic transformer, switch mode power supply .


BLD128D pinout

BLD128D PDF Datasheet

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