2N3906 Transistor Pinout, datasheet, and equivalent

2N3906 Transistor is a popular PNP bipolar junction transistor used in low power and current, medium voltage applications. It is widely used for low power amplification and switching.

2N3906 is complementary to 2N3904 NPN bipolar junction transistor.

2n3906 pnp-transistor in TO-92 package
2n3906 PNP-transistor in TO-92 package

It has a current rating of 200 mA, voltage rating of 40 V, and power rating of 625 mW. And provides a current gain of 100 when the current of 10 mA flows through the collector. 2N3N06 is popular due to its high gain and low saturation voltage.

Note: 2N3906 transistor was first manufactured by Motorola.

2N3906 Transistor Pinout

2N3906 Pinout
2N3906 Pinout

2N3906 pinout has three pins: emitter, base, and collector respectively from left to right(flat side with the leads pointed downward).

2N3906 Transistor datasheet

This transistor is available in Through-hole and a wide variety of SMD packages(SOT23, SOT223, etc) with TO-92 being the most popular one. 2N3906 is called MMBT3906 in SOT23 or SMD package. Or in other words, MMBT3906 is the SMD version of 2N3906.

Given below is the datasheet of the 2N3906 transistor in the TO-92 package:

Download 2N3906 transistor datasheet.

Electrical characteristics, current-voltage ratings, and physical dimensions of the 2n3906 transistor are given in detail in this datasheet.

Given below is the datasheet of 2N3906 (MMBT3906) in the SOT23 package:

Download MMBT3906 transistor datasheet.

2N3906 equivalent

Given below is the list of popular transistors which can be used as a replacement for 2N3906:

BC557, BC527, BC558, BC559, 2N2907, BC556, A1015, C945, 2N4403, 9014.

Specifications of 2N3906 transistor

Collector-Base Voltage60 V
Collector-Emitter Voltage: 40 V
Emitter-Base Voltage: 6 V
Collector Current: 0.2 A
Collector Dissipation –  0.625 W
DC Current Gain (hFE) 100 to 300
Transition Frequency 300 MHz
Noise 5 dB
Junction Temperature Range  55 to +150 °C
2N3906 Transistor specifications table

2N3906 TO-92 Package dimensions

Given below is the image of 2N3906 TO-92 package dimensions. All the dimensions are in mm.

2N3906 physical dimensions
2N3906 package dimensions

2N3906 based electronics projects:

Low light Detector using 23906 with LDR

This circuit detects the low light by turning ON the LED connected between the collector and Ground. During low light in the surrounding, emitter current flows from emitter to collector to Ground lighting up the LED on its way.

Low light detector circuit using 2N3906
Low light detector circuit using 2N3906

In the circuit diagram given above, 2N3906 is used as a switch to turn ON/OFF an LED(depending on the surrounding light) connected at the collector terminal. The complete circuit is powered via a 9 V supply. 

A resistor of 5.6 K Ohm is connected between the load(LED) and the Ground to protect the LED from overcurrent. The required resistor value can be easily calculated using Ohm’s law.

When the light falling on the LDR is significant(low resistance), the base of the transistor is not biased. And zero -ve current flows to the base of the transistor. Due to this, 2N3906 remains in the cut-off state and the LED does not glow.

When there is low light falling on the LDR(high resistance), the base of the transistor is biased, and -ve current flows to the base of the transistor. Due to this biasing current, 2N3906 goes to the saturation state and the LED turns ON.

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