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A TIP31 is a standard type of NPN bipolar junction transistor used for medium power applications. A TIP31 is complementary to a TIP32 PNP bipolar transistor. TIP31 transistors are designated as TIP31A, TIP31B, TIP31 to indicate increasing collector-base and collector-emitter breakdown voltage ratings. The TIP31 is packaged in a TO-220 case. TIP stands for Texas Instruments (Plastic) Power [1][2] transistor. 31 is an arbitrary identifier. The series was listed in a December 1968 data sheet from Texas Instruments [3]


These ratings are for the Fairchild TIP31 series. Other manufacturers may have other ratings for this part. These are absolute maximum ratings and should not be exceeded.

Model Vcb Vce Ice Power (Tc = 25°C)
TIP31 40 40 3A 40W
TIP31A 60 60 3A 40W
TIP31B 80 80 3A 40W
TIP31C 100 100 3A 40W

These characteristics apply to all types of TIP31 transistors (A, B, C). The characteristics are very similar between models, however differences may apply depending on temperature and/or manufacturing process.

Parameter Manufacturer
Fairchild [4] Samsung Semi.[5] Micro Electronics [6]
Vce saturation 1.2V 1.2V 1.2V
Vbe saturation 1.8V 1.8V 1.8V
Small signal DC current gain (Hfe) 25 25 20
Hfe bandwidth product 3.0 MHz 3.0 MHz 3.0 MHz


  1. ^ Transistors
  2. ^ Transistor markings
  3. ^ The Power Semiconductor Data Book for Design Engineers First Edition, Texas Instruments Incorporated, publication no. CC-404 70977-22-IS, no date, page 5-327
  4. ^ [1]
  5. ^ [2]
  6. ^ [3]