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TIP120 NPN Darlington Transistor

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by adom

NPN Darlington power transistor, 60 V / 5 A, with high current gain in a TO-220 package.

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TIP120

STMicroelectronics · Bipolar Transistor (BJT) · TO-220

The TIP120 is an NPN Darlington power transistor rated for 60 V and 5 A continuous collector current. Its Darlington pair gives a high current gain (2500 typical), so a small base current from an MCU or logic pin can switch large loads like motors, relays, solenoids, and lamps. It comes in a TO-220 package with integrated base-emitter resistors and a clamp diode is often paired externally for inductive loads.

Pinout

Pin Name Type Function
1 B input Base of the NPN Darlington pair. Drives the input transistor through an internal 7 kΩ base-emitter shunt (R1); a second 70 Ω resistor (R2) shunts the output stage. Max continuous base current IB = 0.12 A; VBE(on) ≤ 2.5 V at IC = 3 A, VCE = 3 V.
2 C passive Collector of the NPN Darlington output transistor. Electrically common with the TAB (mounting/heat-sink flange). Rated VCEO = 60 V, IC(cont) = 5 A, IC(peak) = 8 A; VCE(sat) ≤ 2 V at IC = 3 A. Includes an internal collector-emitter clamp diode (anode = emitter, cathode = collector) for inductive-load flyback protection.
3 E passive Emitter of the NPN Darlington output transistor; the low-side current-return terminal. Typically tied to ground/common in a low-side switching topology. Carries the full collector current in the on state.

Key specifications

Parameter Value
Type NPN Darlington power transistor
Collector-emitter voltage (VCEO) 60 V
Collector current (IC) 5 A continuous (8 A peak)
DC current gain (hFE) 1000 min, 2500 typ at 3 A
Power dissipation 65 W
VCE(sat) 2.0 V at 3 A
Operating temperature -65 C to 150 C

CAD (KiCad official)

  • Symbol: tip120.kicad_sym
  • Footprint: tip120.kicad_mod
  • 3D model: TO-220 body from KiCad Package_TO_SOT_THT/TO-220-3_Vertical.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: STMicroelectronics datasheet (13 pp, sha256 e726b0e3ab76c110, retrieved 2026-08-17, tier: manufacturer)
  • Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF