B857 PDF Datasheet – 50V, PNP Transistor, 2SB857

This post explains for the transistor.

The Part Number is 2SB857, B857.

The Package is TO-220AB Type

The function of this semiconductor is 50V, 4A, PNP Transistor.

Manufacturer: Renesas

Preview images :B857 pdf datasheet


B857 is -50V, -4A, Silicon PNP Triple Diffused Transistor. A PNP transistor is a type of bipolar junction transistor (BJT) with a different structure and polarity compared to an NPN transistor.


1. Structure: A PNP transistor has a sandwich-like structure, consisting of a thin N-type layer (base) sandwiched between two P-type layers (emitter and collector).

2. Current flow: When a small current is applied to the base terminal, it allows a much larger current to flow from the emitter to the collector. This is called amplification or gain, and it makes the PNP transistor useful as an electronic switch or amplifier.

3. Voltage levels: The voltage levels in a PNP transistor are opposite to those in an NPN transistor. In a NPN transistor, the base-emitter junction is forward-biased and the collector-base junction is reverse-biased.

B857 pinout transistor

Absolute maximum ratings ( Ta=25°C )

1. Collector to Base Voltage: Vcbo = – 70 V

2. Collector to Emitter Voltage: Vceo = – 50 V

3. Emitter to Base Voltage: Vebo = – 5 V

4. Collector Current: Ic = – 4 A

5. Collector Dissipation : Pc = 40 W

6. Junction Temperature: Tj = 150°C

7. Storage Temperature: Tsg = -45 ~ +150°C



1. Low frequency power amplifier complementary pair with 2SD1133 and 2SD1134


B857 PDF Datasheet