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TO-220 · TIP120
ActiveNPN Darlington Power Transistor
TIP120
STMicroelectronics · TO-220 · NPN Darlington Power Transistor
Price on Request
Get a competitive quote within 24 hours. Volume discounts available. Shenzhen stock ships in 1-2 business days.
Overview
The TIP120 is STMicroelectronics' NPN epitaxial Darlington power transistor in TO-220, and its monolithic two-transistor gain stage is the reason it can be driven straight from a microcontroller pin. Ratings are 60V collector-emitter and collector-base, 5V emitter-base, 5A continuous collector current, 8A peak, and 120mA of base current, with 65W of dissipation at TC = 25°C (only 2W free-air at TA = 25°C).
DC current gain is a minimum of 1000 at both IC = 0.5A and IC = 3A with VCE = 3V, so a few milliamps of base current switches several amps of load. The trade-off is the Darlington saturation voltage: 2.0V maximum at IC = 3A with IB = 12mA, and 4.0V maximum at 5A with 20mA, which means several watts of dissipation at full current and makes a heatsink mandatory. Base-emitter on-voltage is about 2.5V, and junction-to-case thermal resistance is 1.92°C/W.
Typical duty includes solenoid and valve drivers, motor on-off control, lamp and heater switching, and linear pass elements where high gain matters more than efficiency. Because TO-220 power parts are profitable to fake, remarked and lower-gain clones circulate; verify hFE at IC = 3A (genuine reads above 1000) and curve-trace VCE(sat) at 3A/12mA before releasing volume. We ship ST-branded TIP120 from authorized channel with certificate of conformance. For efficient switching above a few amps, compare against a logic-level MOSFET such as the IRF3205.
Key Features
- 60V / 5A (8A peak) NPN Darlington in TO-220
- hFE 1000 min at IC = 3A - MCU-direct drive
- 65W dissipation at TC = 25°C, RθJC 1.92°C/W
- Monolithic base-emitter speed-up resistors
- Complementary family with TIP125/126/127
Typical Applications
- Solenoid, valve and relay bank drivers
- DC motor on-off and direction control
- Lamp, heater and high-current load switching
- Linear pass element in simple regulators
- Audio and industrial driver stages
- Microcontroller-direct load switching without a driver IC
Specifications
- Device Type / Polarity
- NPN Darlington
- Collector-Emitter Voltage (VCEO)
- 60 V
- Continuous Collector Current (IC)
- 5 A
- Peak Collector Current (ICM)
- 8 A
- DC Current Gain hFE min (VCE = 3 V, IC = 3 A)
- 1000
- VCE(sat) max (IC = 3 A, IB = 12 mA)
- 2.0 V
- VCE(sat) max (IC = 5 A, IB = 20 mA)
- 4.0 V
- Power Dissipation (PC, TC = 25 °C)
- 65 W
- Pins
- 3
- RoHS
- Compliant
Procurement Tips
For new switching designs above 2A, cost out a logic-level MOSFET before committing to TIP120; where you keep the Darlington, buy ST-branded parts from authorized channel and require an hFE-at-3A sample report per lot.
Frequently Asked Questions
TIP120 vs a MOSFET like IRF3205 - which for a 4A load?
The MOSFET. TIP120 saturates at 2-4V, so at 4A it dissipates 8-16W and needs a large heatsink; an IRF3205 at 8mΩ dissipates about 0.13W at 4A. Choose TIP120 when you need high gain from a weak drive or linear operation; choose a MOSFET for efficient switching.
Can I drive TIP120 directly from a 5V Arduino pin?
Yes for moderate loads. hFE of 1000 means 5mA of base current supports about 5A in principle, but an Arduino pin safely sources about 20-40mA, so use a 220Ω-1kΩ base resistor. Remember VBE is about 1.4-2.5V, and add a base-emitter pulldown to guarantee turn-off.
Why does my TIP120 get so hot even when on?
Because a Darlington never truly saturates: VCE(sat) is 2V at 3A and 4V at 5A. At 3A that is 6W in the package, which without a heatsink drives the junction far past 150°C. Fit a heatsink sized for the real dissipation, or switch to a MOSFET.
TIP120 vs TIP122 - what changes?
Same Darlington family, different voltage: TIP120 is 60V, TIP121 is 80V, TIP122 is 100V. Current, gain and package are identical, so TIP122 is a drop-in upgrade where you need more breakdown margin on inductive or 48V rails.
Is the TIP120 counterfeit-prone and how do I check?
Yes, TO-220 power parts are profitable to remark. Verify hFE at IC = 3A, VCE = 3V (genuine reads above 1000), curve-trace VCE(sat) at 3A/12mA (under 2V), and inspect the laser mark, lead finish and package weight. Clones often show hFE of a few hundred and high saturation. We test samples per lot.
What is the MOQ and lead time?
MOQ is 1 tube (50 pcs) for ST TIP120 in stock, or 1,000 pcs for volume pricing; 10 pcs loose for prototypes. Shenzhen stock ships in 1-2 days; ST authorized-channel replenishment is 10-16 weeks.
Do I need a flyback diode with inductive loads?
Yes, always. Switching a solenoid or motor without a clamp lets the inductive kickback exceed the 60V VCEO rating and destroy the device. Add a 1N4007 or fast Schottky across the coil, oriented to conduct when the transistor turns off.
Alternatives & Equivalents
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