BETACollector limit100 V · absolute VCEO
NPN power transistor
TIP31C Specifications
Review TIP31C electrical specifications, operating conditions and package details.
Package view
Key specifications
The 3 A limit does not promise 3 A from any control output. The saturation test uses 375 mA base current, and allowable dissipation depends on case temperature or the specified PCB.
DC collector limit3 A magnitude · thermal limits apply
DC gain minimum25 IC 1 A · VCE 4 V magnitudes
Junction limit150 °C · absolute
Package details
TIP31CG · TO-220AB
| Property | Details |
|---|---|
| Manufacturer | onsemi |
| Part number | TIP31CG |
| Package | TO-220AB |
| Connections | 3 pins |
| Mounting | Through-hole |
| Lead pitch | 2.54 mm |
| Package code | 221A style 1 |
| Thermal reference | 40 W at case 25°C; 2 W at ambient 25°C |
Device and package scope
Two separately documented selections
Manufacturer specifications 5 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Through-hole | TIP31CG · TO-220 | TIP31A/D Rev. 17, June 2024 |
| Surface-mount | MJD31CT4G · DPAK | MJD31/D Rev. 21, May 2026 |
| Polarity | NPN | Manufacturer tables use magnitudes; reverse voltage/current signs for PNP |
| Terminals | B1 · C2 · E3 | Tab/contact 4 is electrically collector |
| SMD relationship | Electrically similar manufacturer counterpart | Different power and leakage limits; check the selected package |
No specifications match. Try a parameter name or a unit.
Pin function is preserved when the package changes.
Absolute voltage and current limits
Magnitudes; individual stress limits
Manufacturer specifications 5 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Collector-emitter / collector-base | 100 / 100 V | Selected C-voltage grades only |
| Emitter-base reverse voltage | 5 V | Do not apply a reverse drive without limiting it |
| DC / peak collector current | 3 / 5 A | Thermal and pulse restrictions also apply |
| Base current | 1 A | Absolute maximum |
| Junction and storage | −65 to +150°C | Both selected references |
No specifications match. Try a parameter name or a unit.
These are not simultaneous operating targets.
Gain and on-state characteristics
TC 25°C; pulse ≤300 µs, duty ≤2%
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| hFE at IC 1 A | 25 minimum | VCE 4 V |
| hFE at IC 3 A | 10–50 | VCE 4 V |
| Collector-emitter saturation | 1.2 V maximum | IC 3 A; IB 375 mA |
| Base-emitter on voltage | 1.8 V maximum | IC 3 A; VCE 4 V |
| Current gain-bandwidth | 3 MHz minimum | IC 500 mA; VCE 10 V; test 1 MHz |
| Small-signal gain | 20 minimum | IC 500 mA; VCE 10 V; 1 kHz |
No specifications match. Try a parameter name or a unit.
Active-region gain does not replace a saturation base-current budget.
Off-state characteristics
Maximum magnitudes at TC 25°C
Manufacturer specifications 5 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| TO-220 ICEO | 0.3 mA | VCE 60 V; base open |
| DPAK ICEO | 50 µA | VCE 60 V; base open |
| TO-220 ICES | 200 µA | VCE 100 V; VEB 0 |
| DPAK ICES | 20 µA | VCE 100 V; VEB 0 |
| Emitter leakage | 1 mA | VBE reverse 5 V; collector open |
No specifications match. Try a parameter name or a unit.
Leakage can matter even when the load is meant to be off.
Package-specific thermal limits
The boundary condition changes the rating
Manufacturer specifications 7 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| TO-220 power / derating | 40 W / 0.32 W per °C | Case 25°C / above 25°C |
| TO-220 ambient power | 2 W | Ambient 25°C; derate 0.016 W/°C |
| TO-220 RθJC / RθJA | 3.125 / 62.5°C/W | Maximum reference values |
| DPAK power / derating | 15 W / 0.12 W per °C | Case 25°C / above 25°C |
| DPAK ambient power | 1.56 W | FR-4, 165 mm², 1 oz copper; derate 0.012 W/°C |
| DPAK RθJC / RθJA | 8.3 / 80°C/W | Specified mounting and minimum-pad conditions |
| Safe operating area | Check manufacturer curves | Voltage, current, duration and starting temperature together |
No specifications match. Try a parameter name or a unit.
The package image is not a heatsink rating.
12 V resistor-load switch
Explicit illustrative assumptions
Manufacturer specifications 7 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Load | 100 Ω, at least 3 W | Supply to collector |
| Base resistor / return | 330 Ω / 10 kΩ | Return resistor goes from base to emitter |
| Buffered driver | 0 V off / 5 V on | Must source about 12.7 mA |
| Assumed junctions | |VBE| 0.8 V; |VCE| 0.2 V | Teaching assumptions, not guaranteed test points |
| Base current | 12.65 mA | (5−0.8)/330−0.8/10000 |
| Collector current / forced ratio | 118 mA / 9.33 | (12−0.2)/100; IC/IB |
| Transistor / load loss | 33.7 mW / 1.392 W | Include base contribution; allow resistor thermal margin |
No specifications match. Try a parameter name or a unit.
Inductive loads require a suitable clamp and a separate transient check.
Connections by function
Select a pin for its function, connection guidance and electrical notes.