TIP127 — -100V -5A PNP Power Darlington Transistor (TO-220)

Overview

The TIP127 (along with TIP125 and TIP126) is a -100V -5A complementary silicon PNP power Darlington transistor manufactured by STMicroelectronics, onsemi, and Texas Instruments. Housed in an industry-standard TO-220AB through-hole package, it serves as the official PNP complement to the iconic TIP122 (and TIP120/TIP121 series).

Monolithically integrating two cascaded PNP transistors in a Darlington configuration with built-in base-emitter bleed resistors and an integrated anti-parallel damper protection diode, the TIP127 provides high current gain ( $h_{FE} \ge 1000$ ). It allows high-current $3\text{A} \dots 5\text{A}$ high-side inductive loads to be switched on $24\text{V} \dots 48\text{V}$ power rails using a modest base pull-down current of just a few milliamps. The TIP127 is standard equipment in discrete high-power H-bridge bidirectional DC motor drivers, high-side automotive relay switches, audio amplifier power stages, and industrial solenoid controllers.

Quick reference


Transistor Type	Monolithic PNP Silicon Power Darlington BJT
Package	TO-220AB (3-pin through-hole)
Collector-Emitter Breakdown ( $V_{CEO}$ )	$-100\text{ V}$ max (TIP127) / $-60\text{ V}$ max (TIP125)
Collector-Base Breakdown ( $V_{CBO}$ )	$-100\text{ V}$ max (TIP127) / $-60\text{ V}$ max (TIP125)
Continuous Collector Current ( $I_C$ )	$-5.0\text{ A}$ max ( $-8.0\text{ A}$ pulsed)
Base Current ( $I_B$ )	$-0.12\text{ A}$ ( $-120\text{ mA}$ )
DC Current Gain ( $h_{FE}$ )	$1000$ min ( $1000 \dots 5000$ at $I_C = -3.0\text{A}, V_{CE} = -3.0\text{V}$ )
Collector Saturation ( $V_{CE(sat)}$ )	$-2.0\text{ V}$ max at $I_C = -3.0\text{A}$ ( $-4.0\text{ V}$ max at $-5.0\text{A}$ )
Total Power Dissipation ( $P_D$ )	$65\text{ Watts}$ ( $T_C = 25^\circ\text{C}$ with heatsink) / $2.0\text{ W}$ free air
Integrated Components	Base-Emitter Bleed Resistors + Flywheel Clamping Diode
Complementary NPN Pair	TIP122 (100V NPN) / TIP120 (60V NPN)

Pinout (TO-220AB Package - B-C-E Standard)

Looking at the front labeled face with leads pointing downward:

text

        ┌──────────────┐
        │  O  [Metal]  │ ── Tab is internally connected to Pin 2 (Collector)
        ├──────────────┤
        │    TIP127    │
        └─┬────┬────┬──┘
          1    2    3
          B    C    E

Pin	Name	Type	Description
1	`BASE (B)`	Base Input	Base control input (Driven LOW to turn ON via small NPN driver)
2 (Tab)	`COLLECTOR (C)`	Power Collector	Collector output (Connected to load; internally bonded to metal tab)
3	`EMITTER (E)`	Power Emitter	Emitter terminal (Connected to positive supply rail, e.g. $+24\text{V} \dots +48\text{V}$ )

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Collector-Emitter Breakdown	$V_{(BR)CEO}$	-100	—	—	V	$I_C = -30\text{mA}, I_B = 0$ (TIP127)
Collector-Emitter Breakdown	$V_{(BR)CEO}$	-60	—	—	V	$I_C = -30\text{mA}, I_B = 0$ (TIP125)
Collector-Base Breakdown	$V_{(BR)CBO}$	-100	—	—	V	$I_C = -1.0\text{mA}, I_E = 0$ (TIP127)
Emitter-Base Breakdown	$V_{(BR)EBO}$	-5.0	—	—	V	$I_E = -2.0\text{mA}, I_C = 0$
Collector Cutoff Current	$I_{CEO}$	—	—	-500	µA	$V_{CE} = -50\text{V}, I_B = 0$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	1000	—	—	—	$I_C = -0.5\text{A}, V_{CE} = -3.0\text{V}$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	1000	—	—	—	$I_C = -3.0\text{A}, V_{CE} = -3.0\text{V}$
Collector Saturation Voltage	$V_{CE(sat)}$	—	—	-2.0	V	$I_C = -3.0\text{A}, I_B = -12\text{mA}$
Base-Emitter On Voltage	$V_{BE(on)}$	—	—	-2.5	V	$I_C = -3.0\text{A}, V_{CE} = -3.0\text{V}$

Typical Application Circuit: Discrete Full H-Bridge DC Motor Driver

In an H-bridge, two high-side TIP127 (PNP) Darlington transistors pair with two low-side TIP122 (NPN) Darlington transistors:

text

                            +24V Motor Power Rail
                                      │
                 ┌────────────────────┴────────────────────┐
                 │                                         │
          [Pin 3: EMITTER]                          [Pin 3: EMITTER]
            TIP127 (Left High)                        TIP127 (Right High)
  NPN ───►[Pin 1: BASE]                             [Pin 1: BASE]◄─── NPN
          [Pin 2: COLLECTOR]                        [Pin 2: COLLECTOR]
                 │                                         │
                 ├─────────[ + DC Motor - ]────────────────┤
                 │                                         │
          [Pin 2: COLLECTOR]                        [Pin 2: COLLECTOR]
            TIP122 (Left Low)                         TIP122 (Right Low)
  MCU ───►[Pin 1: BASE]                             [Pin 1: BASE]◄─── MCU
          [Pin 3: EMITTER]                          [Pin 3: EMITTER]
                 │                                         │
                 └────────────────────┬────────────────────┘
                                      │
                                  GND (0V)

Voltage Breakdown Family Guide

Part Number	Polarity	$V_{CEO}$ Voltage	Complementary NPN
TIP125	PNP Darlington	$-60\text{ V}$	TIP120
TIP126	PNP Darlington	$-80\text{ V}$	TIP121
TIP127	PNP Darlington	$-100\text{ V}$ (Most Popular)	TIP122

Common mistakes

Forgetting the ~2V Darlington saturation loss: Like its NPN twin, $V_{CE(sat)} \approx 2.0\text{V}$ under load. Dissipated power ( $P = 2.0\text{V} \times 3\text{A} = 6\text{W}$ ) requires a heatsink for continuous currents above $1.5\text{A}$ .
Connecting base directly to MCU on 24V supply: Never connect Pin 1 (Base) directly to an MCU GPIO when the Emitter is tied to $+24\text{V}$ . Use a small NPN transistor (e.g. 2N3904) to pull the base LOW.

Notes

Suffix Guide: TIP127 is standard TO-220; TIP127G denotes lead-free RoHS compliance.

Interface	Direct MCU Logic Gate Drive Compatible with Open-Collector Driver (hFE >= 1000)
Package	TO-220AB (3-pin through-hole)