STMicroelectronics TIP127

Overview

TIP127 from STMicroelectronics is a PNP monolithic 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 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 relay/actuator switching.

For engineers reviewing the TIP127 datasheet, TIP127 pinout, TIP127 application, or TIP127 equivalent, key selection criteria include its complementary PNP polarity, −100 V V_CEO rating, integrated bias network, thermal resistance (R_thJC = 1.92 °C/W), and safe operating area for DC and pulsed loads up to 8 A peak.

Technical Context

The TIP127 implements a planar "base island" Darlington structure with monolithically integrated input resistors-R1 provides base current limiting and R2 enables turn-off acceleration. Its negative voltage/current ratings reflect PNP operation: V_CBO = −100 V, V_EBO = −5 V, and I_CM = −8 A peak.

Thermal performance is defined by R_thJC = 1.92 °C/W and R_thJA = 62.5 °C/W, supporting high-power dissipation when mounted on heatsinks. Electrical behavior includes low saturation voltage (−2 V typ. at −3 A), high DC gain (≥1000), and fast switching with delay/rise times under 100 ns at −2 A load.

Key Specifications

Pinout & Package

TO-220 type H package with electrically isolated metal tab (pin 2). Pin 1 is emitter (E), pin 2 is collector (C, connected to tab), pin 3 is base (B). Tab must be insulated from chassis unless circuit design requires collector-to-chassis connection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD127 and BDX54C, the TIP127 uniquely combines through-hole robustness, integrated biasing, and 65 W thermal capability-making it optimal for industrial control boards requiring field-replaceable, heatsink-mounted high-current switches without layout redesign.

Availability

TIP127 is available at Aetrix Electronics and suitable for industrial relay drivers, DC motor reversing circuits, linear voltage regulators, and high-voltage LED dimming requiring stable component supply and long-term production continuity.

Supply support for TIP127 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, specializing in power management, analog, MEMS, and microcontrollers.

The TIP127 belongs to ST's STPOWER bipolar transistor family, engineered for rugged industrial switching and linear regulation where high gain, low saturation, and thermal reliability are essential.

FAQ

Is the TIP127 pin-compatible with the TIP122?

No-TIP127 is PNP while TIP122 is NPN; their pinouts are mirror-symmetric but not interchangeable. Pin 1 is emitter for both, but polarity reversal means connecting them identically will cause reverse-bias failure. Use only as complementary pairs in H-bridges or dual-rail designs.

Can the TIP127 operate without a heatsink?

Only at very low duty cycles and ambient temperatures ≤25°C. At 5 A continuous, junction temperature exceeds 150°C within seconds without heatsinking. R_thJA = 62.5 °C/W mandates a heatsink for any sustained load above ~0.5 A, per thermal calculations in DS0854 Section 2.

What is the purpose of the internal R1 and R2 resistors?

R1 (16 kΩ) limits base current during turn-on; R2 (60 Ω) provides a discharge path for stored base charge during turn-off, reducing storage time and improving switching speed. This eliminates external base resistors in most logic-driven applications.

Does the metal tab connect to collector internally?

Yes-the TO-220 type H package bonds the collector directly to the metal tab (pin 2). The tab is electrically isolated from the mounting surface per ECOPACK specifications, but must be insulated from chassis unless circuit design intentionally references collector to ground or heatsink potential.