BD136 PNP Power Transistor

BD136 is a PNP transistor hence the collector and emitter will be closed (Forward biased) when the base pin is held at ground and will be opened (Reverse biased) when a signal is provided to base pin. This is where a PNP transistor differs from a NPN transistor, if you are looking for an equivalent NPN type check out BD135 transistor.

BD136 has a gain value of 40 to 250, this value determines the amplification capacity of the transistor. The maximum amount of current that could flow through the Collector pin is 1.5A, hence we cannot connect loads that consume more than 1.5A using this transistor. To bias a transistor we have to supply current to base pin, this current (IB) should be limited to 5mA and voltage across the base emitter pin should be 5V.

When this transistor is fully biased then it can allow a maximum of 1.5A to flow across the collector and emitter. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (V­CE) or Base-Emitter (VBE) could be 45V and 45V respectively. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region and the Base Emitter voltage could be around 500 mV.