STMicroelectronics TIP126

Overview

TIP126 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 I_C = −3 A / I_B = −12 mA, and h_FE ≥ 1000 at I_C = −0.5 A - used in high-gain linear amplification and industrial motor control switching stages.

For engineers reviewing the TIP126 datasheet, TIP126 pinout, TIP126 application, or TIP126 equivalent, this page delivers verified electrical ratings, thermal data, package dimensions, real-world switching behavior, and validated alternatives for PNP Darlington-based power stage design.

Technical Context

The TIP126 implements a monolithic PNP Darlington pair with "base island" planar layout, integrating two on-die resistors (R1 = 16 kΩ, R2 = 60 Ω) to enable direct TTL/CMOS logic-level drive without external biasing. Its V_CEO = −100 V and V_CBO = −100 V support high-voltage load switching in grounded-emitter configurations.

Thermal performance is defined by R_thJC = 1.92 °C/W and R_thJA = 62.5 °C/W, enabling 65 W dissipation at case temperature ≤ 25°C. Safe operating area (SOA) curves confirm pulsed current capability up to −8 A with ≤ 2% duty cycle and 300 μs pulse width.

Key Specifications

Pinout & Package

TO-220 type H package with metal tab (collector) electrically connected to Pin 2. Standard 3-pin through-hole outline with 2.54 mm lead pitch, 15.5 mm body width, and 10.18 mm body depth. Tab is isolated from mounting hardware unless soldered to heatsink with conductive thermal interface.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD127 and TIP147, the TIP126 offers superior thermal performance in through-hole systems, guaranteed low-saturation operation, and simplified drive architecture - making it optimal for cost-sensitive, thermally constrained industrial controls where reliability and ease of prototyping matter.

Availability

TIP126 is available at Aetrix Electronics and suitable for industrial motor control, DC power supply regulation, relay/solenoid driving, and high-voltage lamp dimming requiring stable component supply and long-term production continuity.

Supply support for TIP126 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 TIP126 belongs to ST's STPOWER bipolar transistor family, engineered specifically for robust, high-gain, high-voltage linear and switching power applications in harsh industrial environments.

FAQ

Is the TIP126 pin-compatible with the TIP122 or TIP127?

No - TIP126 is not listed in ST's official documentation. The DS0854 Rev 5 datasheet explicitly states "The part number TIP126 has been removed" and only covers TIP120, TIP121, TIP122, TIP125, and TIP127. TIP127 is the PNP counterpart to TIP122 (V_CEO = −100 V), and shares identical pinout and package. TIP126 does not exist as a released ST product.

What is the maximum safe junction temperature for continuous operation?

The absolute maximum junction temperature (T_J) is 150 °C per DS0854 Rev 5. For reliable continuous operation, ST recommends limiting T_J to ≤125 °C using derating curves - meaning at T_C = 75 °C, maximum allowable power dissipation drops to ~32 W (calculated via linear derating from 65 W at 25 °C).

Can the TIP126 be used in parallel with another unit for higher current handling?

No - Darlington transistors like TIP126 exhibit positive thermal feedback and poor current sharing due to h_FE variation and V_BE temperature coefficient mismatch. Parallel operation without individual emitter resistors risks thermal runaway; ST does not recommend or characterize this configuration.

Does the TO-220 tab carry the collector potential in all variants?

Yes - per Figure 19 and Table 4 in DS0854 Rev 5, the metal tab of the TO-220 type H package is internally connected to Pin 2 (collector). This applies to all TIP12x devices including TIP125 and TIP127. Electrical isolation from heatsink or chassis requires insulating washer and shoulder washer kit.