TIP31 NPN Power Transistor
TIP31 NPN Power Transistor

TIP31 Transistor specs

  • It is NPN Transistor
  • DC Current Gain range is 10 to 50hFE
  • Collector current (IC) is 3A
  • Collector to base Voltage (VCB) is 40V
  • Collector to emitter voltage (VCE) is 40v
  • Emitter to base voltage (VEB) is 5V
  • Junction temperature (TJ) is 150°C
  • Base Current (IB) is 1A
  • Transition frequency (FT) is 3MHz

TIP31 Transistor pinout

Pin Number Pin Name Description
1 Base The base terminal triggers the device
2 Collector Current flow through the collector
3 Emitter Current flows through the emitter


TIP31 transistor pinout diagram
TIP31 transistor pinout diagram

TIP31 Transistor package

TIP31 NPN transistor package
TIP31 NPN transistor package
  • The package used at the TIP31 transistor in TO-220.
  • It is a type of power transistor package, at the package, we can see two sections.
  • First is the front portion, which is made with the plastic and epoxy material mixture, this gives the transistor less expensive and compactness.
  • And the back end is made with metal material, which is acts as a heat sink for the transistor.
  • The hole at the package is used to attach the external heat sink and support the circuit to attach it with the PCB.

C1815 transistor

TIP31 Transistor Description

The transistor TIP31 is known as the medium power, high current transistor device and this is why they had applications on power circuits.

The current gain of the TIP31 transistor will start from 10 to 50hFE, this is an important value when we use this transistor in amplifier applications, and the TIP31 transistor had low current gain. 

The maximum collector current on the TIP31 transistor is 3A, which means the allowable load current for the TIP31 transistor, this is an important factor in amplifier and voltage regulator applications.

The base current of this transistor is 2A, the maximum allowable base voltage to trigger the transistor ON.

The power dissipation on the TIP31 transistor is 40W, this particular value indicates the power dissipation of the transistor device, and we need to give the main role for the package for this.

The transition frequency on this transistor is 3MHZ, it is an important factor in switching applications.

The junction temperature of the TIP31 transistor is 150°C.

TIP31 Transistor datasheet 

TIP31 NPN transistor datasheet 
TIP31 NPN transistor datasheet

If you need the datasheet in pdf please click this link

Tip31 transistor Equivalent 

  • The equivalent transistor for the TIP31 device will be BDT31, TIP120, TIP31G, BDT31B, and TIP122.
  • Each one in this is perfect equivalent transistors for TIP31, but most of them had higher voltage and current value than TIP31.
  • So at the replacement, we need to stick to the electrical characteristics.
  • Other than this, they are known as the best equivalent for the TIP31 transistor device.

TIP31 vs TIP41 vs TIP31c vs TIP120

  • The table below is the comparison between TIP31 vs TIP31c and TIP41 vs TIP120.
  • The comparison table had the information’s about the electrical characteristics of each transistor in the list.
  • This comparison of the similar transistor is really helpful for replacement purposes.
Characteristics Tip31 Tip41 Tip31c Tip120
Collector to base voltage (VCB)40V40V100V60V
Collector to emitter voltage (VCE) 40V40V100V60V
Emitter to base voltage (VEB)5V5V5V5V
Collector current (IC)3A6A3A5A
Power dissipation 40W65W40W65W
Junction temperature (TJ)150°C150°C150°C150°C
Transition frequency (FT)3MHZ3MHZ3MHZ-
Noise (N)----
Gain (hFE)10 to 50hFE15to 75hFE10 to 50hFE1000hFE
Package TO-220TO-220TO-220TO-220

Tip31 transistor uses

  • At audio amplifier circuits
  • At switching applications
  • Voltage regulator circuits
  • Power supply circuits
  • Battery charger circuits

Tip31 transistor amplifier circuit

Tip31 transistor amplifier circuit
Tip31 transistor amplifier circuit
  • The figure shows the amplifier circuits based on op-amp and a complementary transistor network.
  • The important point of this amplifier circuit is that the input signal is fully responsible for the working of the op-amp and push-pull network.
  • The combined operation of NE55534 and tip31 and tip32 make the audio output. 

TIP31 LED music circuit

TIP31 LED music circuit
TIP31 LED music circuit
  • The figure shows a circuit for an LED music circuit using a TIP31 transistor.
  • Most of the music LED circuits had one channel, but here we have two channels.
  • So the working is simple, the signal from the mic is used to trigger both the transistor.
  • Then the transistors amplify the signal and forwarded it to the LEDs.
  • The LED stars glow with the music we play.

Tip31 transistor price

  • The TIP31 transistor is a medium power high current transistor device, which had more applications at power electronic circuits.
  • The price for a TIP41 transistor is 13rsrupees per piece or 0.18USD dollars.

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