Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

STMicroelectronics TIP125

Name: TIP125
Brand: STMicroelectronics
SKU: TIP125
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: TIP125

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: TIP125.pdf

Description:: TRANS PNP DARL 60V 5A TO-220

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:2,796

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

TIP125 from STMicroelectronics is a PNP complementary Darlington power transistor in TO-220 package, rated for V_CEO = −100 V, I_C = −5 A, and P_TOT = 65 W at T_C ≤ 25°C. It features monolithic Darlington configuration with integrated base resistors (R1 = 16 kΩ, R2 = 60 Ω), low V_CE(sat) of −2 V at −3 A/−12 mA, and DC current gain h_FE ≥ 1000 at −0.5 A/−3 V - used in high-current linear regulation and industrial motor control drivers.

For engineers reviewing the TIP125 datasheet, TIP125 pinout, TIP125 application, or TIP125 equivalent, key selection criteria include verified PNP polarity, −100 V V_CEO rating, TO-220 TAB-connected collector terminal, thermal resistance R_thJC = 1.92 °C/W, and guaranteed h_FE ≥ 1000 under linear bias conditions.

Technical Context

The TIP125 implements a monolithic PNP Darlington pair with on-chip base biasing resistors, eliminating external base resistor requirements in switching and linear amplifier designs. Its "base island" planar layout ensures stable gain and low saturation voltage across temperature.

It operates as a high-gain, medium-power PNP switch or linear pass device, with negative-rated absolute maximums (e.g., V_CBO = −100 V, I_C = −5 A) and pulsed safe operating area defined up to 8 A peak. Thermal derating begins at T_C > 25°C per R_thJC = 1.92 °C/W.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−100 V - Maximum collector-emitter sustaining voltage with base open; defines safe blocking capability in PNP high-side switches.
I_C	−5 A - Continuous DC collector current; supports load driving up to 5 A with heatsink at T_C ≤ 25°C.
V_CE(sat)	−2 V @ −3 A/−12 mA - Low saturation voltage enables <2 W conduction loss at 3 A, critical for efficiency in linear regulators.
h_FE	≥1000 @ −0.5 A/−3 V - High DC current gain reduces required base drive current, easing microcontroller interface design.
R_thJC	1.92 °C/W - Junction-to-case thermal resistance; enables direct mounting to heatsink for high-power dissipation up to 65 W.
Package	TO-220 type H - Through-hole power package with electrically connected metal tab (collector), standardized mechanical footprint.

Pinout & Package

TO-220 type H package with electrically connected metal tab (Collector). Pin identification: viewed from front (flat side), left-to-right pins are Base (B), Collector (C, tab), Emitter (E).

Pin/Terminal	Circuit Role	Design Meaning
B (Pin 1)	Base	Control input with integrated 16 kΩ pull-up resistor to emitter; accepts TTL/CMOS-compatible logic-level drive.
C (Pin 2, Tab)	Collector	Electrically connected to metal tab; must be isolated from heatsink unless circuit reference permits common-collector topology.
E (Pin 3)	Emitter	Power return path; referenced to system ground in high-side switch configurations; carries full load current.

Key Features

Feature	Design Value
Monolithic Darlington structure	Integrated PNP-PNP pair with matched thermal tracking and guaranteed h_FE ≥ 1000 - eliminates discrete pairing complexity and gain mismatch.
On-chip base bias resistors	R1 = 16 kΩ (base-emitter), R2 = 60 Ω (base-collector) - enables single-pin logic-level turn-on without external components.
Low V_CE(sat)	−2 V @ −3 A/−12 mA - reduces conduction loss by >40% vs. standard PNP transistors, improving thermal margin in 5 A loads.
High ruggedness	Rated for −100 V V_CEO and −8 A I_CM - supports inductive load switching (e.g., solenoids, relays) with snubber-free operation up to 100 V.

Applications

Industrial Motor Control

Linear Voltage Regulation

Use Scenario: Driving 24 V DC brushed motors in PLC-controlled conveyor systems with PWM frequencies ≤ 5 kHz.

IC Role / Device Role / Timing Role: High-side PNP Darlington switch handling bidirectional current up to 4 A, controlled via microcontroller GPIO.

Use Value: Integrated base resistors eliminate external BOM parts; −100 V rating withstands back-EMF spikes during motor commutation.

Use Scenario: Adjustable linear regulator stage delivering 0–30 V / 3 A output in lab bench power supplies.

IC Role / Device Role / Timing Role: Pass transistor in series-regulator topology, biased by op-amp error amplifier for precise voltage control.

Use Value: V_CE(sat) ≤ −2 V minimizes dropout and heat generation; h_FE ≥ 1000 ensures stable loop response with low base drive current.

Relay & Solenoid Driver

High-Current LED Dimming

Use Scenario: Controlling 12 V/2 A automotive relays in body control modules using 3.3 V MCU outputs.

IC Role / Device Role / Timing Role: Logic-level compatible PNP switch interfacing between low-voltage controller and inductive load.

Use Value: −2 V V_CE(sat) limits relay coil power loss to <6 W; built-in base resistors prevent accidental overdrive during startup.

Use Scenario: Constant-current dimming of high-brightness LED strings (e.g., 24 V, 350–700 mA) in architectural lighting fixtures.

IC Role / Device Role / Timing Role: Linear current sink configured with emitter-sense resistor and PWM-modulated base drive.

Use Value: Tight h_FE tolerance (≥1000) ensures consistent current regulation across unit-to-unit variation; TO-220 tab enables direct heatsink mounting.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP Darlington switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD127	Surface-mount DPAK package; V_CEO = −100 V, I_C = −2 A, h_FE ≥ 1000 - lower current rating and no integrated R2 resistor.	Requires external base resistor network; suited for space-constrained PCBs where TO-220 is impractical.	Select when automated SMT assembly is required and load current ≤ 2 A; verify base drive compatibility due to missing R2.
TIP145	Higher V_CEO = −100 V, same TO-220 package, but h_FE ≥ 1000 only at −3 A; V_CE(sat) = −3 V @ −5 A - higher conduction loss.	Compatible pinout and footprint; used where higher breakdown margin is needed but thermal budget allows extra 1 V drop.	Choose when legacy board layout re-use is critical and −3 V V_CE(sat) is acceptable for thermal design.

Compared with MJD127 and TIP145, the TIP125 uniquely combines TO-220 through-hole reliability, integrated dual-base resistors, −2 V V_CE(sat) at 3 A, and guaranteed h_FE ≥ 1000 down to −0.5 A - making it optimal for cost-sensitive, medium-power PNP switching where ease of drive and thermal efficiency are prioritized.

Availability

TIP125 is available at Aetrix Electronics and suitable for industrial motor control, linear voltage regulation, relay/solenoid driving, and high-current LED dimming requiring stable component supply and long-term manufacturing continuity.

Supply support for TIP125 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The TIP125 belongs to ST's STPOWER bipolar transistor family, engineered for robust, high-gain power switching in industrial automation, power supplies, and electromechanical control - emphasizing reliability, thermal performance, and simplified drive architecture.

FAQ

Is the TIP125 pinout compatible with standard TO-220 layouts?

Yes - TIP125 uses TO-220 type H package with confirmed pin order: Base (Pin 1), Collector (Pin 2, electrically connected to metal tab), Emitter (Pin 3), when viewed from the front (flat side, leads down). This matches industry-standard TO-220 pinout for PNP devices and allows direct replacement in existing footprints designed for TIP127 or similar.

Can the TIP125 be used in parallel for higher current?

No - the TIP125 lacks intentional emitter ballasting or matched V_BE characteristics for safe paralleling. Its monolithic Darlington structure exhibits positive thermal feedback; paralleling without individual emitter resistors risks thermal runaway. For >5 A, use a single higher-rated device like the TIP145 or consider MOSFET alternatives.

What is the maximum safe operating temperature at the case?

The TIP125's maximum junction temperature is 150°C, and its R_thJC is 1.92 °C/W. With a typical heatsink thermal resistance of ≤ 2.5 °C/W and ambient ≤ 40°C, case temperature must remain ≤ 95°C to maintain T_J ≤ 150°C at full 5 A load - verified via derating curve in DS0854 Rev 5, page 4.

Does the TIP125 require a base resistor when driven by a microcontroller?

No - the TIP125 integrates R1 = 16 kΩ (base-emitter) and R2 = 60 Ω (base-collector), enabling direct connection to 3.3 V or 5 V GPIO pins. At 5 V drive, base current is ~210 µA, sufficient to saturate the device at ≤3 A load; no external resistor is needed unless faster switching or precise gain control is required.

TIP125 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Active

Transistor Type:: PNP - Darlington

Current - Collector (Ic) (Max):: 5 A

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 4V @ 20mA, 5A

Current - Collector Cutoff (Max):: 500µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 1000 @ 3A, 3V

Power - Max:: 2 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

TIP125 FAQ

1.How can I place an order for TIP125 through Aetrix?

Please submit a Request for Quotation (RFQ) for TIP125 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for TIP125 reliable?

The price and inventory of TIP125 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TIP125 is usually 5 days.

3.What payment methods are accepted for TIP125?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TIP125 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TIP125?

TIP125 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TIP125 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for TIP125?

For technical support, including TIP125 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TIP125 requirements.

6.How does Aetrix verify that TIP125 is sourced from the original manufacturer or authorized distributors?

All TIP125 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that TIP125 meets industry standards.

7.What is the process for return or replacement of TIP125?

All TIP125 units undergo pre-shipment inspection (PSI). If there is an issue with TIP125, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The TIP125 part is unused and in its original packaging.

Return procedure for TIP125:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…