BD140 — -80V -1.5A Medium-Power PNP Bipolar Junction Transistor (TO-126)

Overview

The BD140 is an iconic -80V -1.5A medium-power complementary silicon PNP bipolar junction transistor manufactured by STMicroelectronics, onsemi, and NXP. Housed in a through-hole TO-126 (SOT-32) plastic package with a central mounting screw hole, it is globally celebrated as the premier audio driver PNP transistor.

Featuring a collector-emitter breakdown voltage ( $V_{CEO}$ ) of $-80\text{V}$ , a continuous collector current rating of $-1.5\text{A}$ ( $-3.0\text{A}$ pulsed peak), a high transition frequency ( $f_T$ ) of $190\text{ MHz}$ , and linear gain tracking, the BD140 is the official complementary PNP pair to the BD139. Together, the BD139/BD140 complementary pair is the undisputed industry standard for hi-fi audio power amplifier push-pull driver stages, discrete Class-A headphone amplifiers (e.g. JLH 1969 / Lehmann clones), active audio preamplifiers, and dual-rail laboratory power supplies.

Quick reference


Transistor Type	Medium-Power Complementary Silicon PNP BJT
Package	TO-126 / SOT-32 (3-pin through-hole with mounting hole)
Collector-Emitter Breakdown ( $V_{CEO}$ )	$-80\text{ V}$ max
Collector-Base Breakdown ( $V_{CBO}$ )	$-80\text{ V}$ max ( $-100\text{ V}$ peak)
Continuous Collector Current ( $I_C$ )	$-1.5\text{ A}$ max ( $-3.0\text{ A}$ peak pulse)
Base Current ( $I_B$ )	$-0.5\text{ A}$ max
DC Current Gain ( $h_{FE}$ )	$40$ to $250$ (BD140-10: 63–160, BD140-16: 100–250)
Transition Frequency ( $f_T$ )	$190\text{ MHz}$ typ ( $> 50\text{ MHz}$ min)
Power Dissipation ( $P_D$ )	$12.5\text{ Watts}$ ( $T_C = 25^\circ\text{C}$ with heatsink) / $1.25\text{ W}$ in free air
Complementary NPN Pair	BD139 (80V NPN)

Pinout (TO-126 / SOT-32 Package - E-C-B Standard)

Looking at the printed front face of the TO-126 package with leads pointing downward:

text

        ┌───────────────┐
        │   O [Mount]   │
        ├──────────────┤
        │     BD140     │
        └─┬─────┬─────┬─┘
          1     2     3
          E     C     B

Pin	Name	Type	Description
1	`EMITTER (E)`	Emitter Terminal	Emitter (Connect to positive supply rail or output summing resistor)
2	`COLLECTOR (C)`	Collector Terminal	Collector (Connected to negative power rail; internally bonded to rear metal tab)
3	`BASE (B)`	Base Terminal	Base control input (Driven with audio VAS output signal)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Collector-Emitter Breakdown	$V_{(BR)CEO}$	-80	—	—	V	$I_C = -10\text{mA}, I_B = 0$
Collector-Base Breakdown	$V_{(BR)CBO}$	-80	—	—	V	$I_C = -100\ \mu\text{A}, I_E = 0$
Emitter-Base Breakdown	$V_{(BR)EBO}$	-5.0	—	—	V	$I_E = -10\ \mu\text{A}, I_C = 0$
Collector Cutoff Current	$I_{CBO}$	—	—	-100	nA	$V_{CB} = -30\text{V}, I_E = 0$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	40	—	250	—	$I_C = -150\text{mA}, V_{CE} = -2.0\text{V}$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	25	—	—	—	$I_C = -500\text{mA}, V_{CE} = -2.0\text{V}$
Collector Saturation Voltage	$V_{CE(sat)}$	—	—	-0.50	V	$I_C = -500\text{mA}, I_B = -50\text{mA}$
Base Saturation Voltage	$V_{BE(sat)}$	—	—	-1.00	V	$I_C = -500\text{mA}, I_B = -50\text{mA}$

Typical Application: Complementary Push-Pull Audio Buffer (Class AB)

text

                            +15V to +24V Positive Supply Rail
                                          │
                                   [Pin 2: COLLECTOR]
                                      BD139 (NPN)
  Audio Input (from Op-Amp)        [Pin 3: BASE]
           │                              │
           ├───[ 1N4148 Diode Bias 1 ]────┤
           │                              │
           │                       [Pin 1: EMITTER]
           │                              │
           │                              ├───[ 0.47Ω 2W Emitter Resistor ]───┐
           │                                                                  ├────► Audio Output (Speaker / Headphones)
           │                              ┌───[ 0.47Ω 2W Emitter Resistor ]───┘
           │                       [Pin 1: EMITTER]
           │                              │
           └───[ 1N4148 Diode Bias 2 ]────┤
                                      BD140 (PNP)
                                   [Pin 3: BASE]
                                          │
                                   [Pin 2: COLLECTOR]
                                          │
                            -15V to -24V Negative Supply Rail

Comparison: BD140 vs TIP42C vs 2N2907A

Parameter	2N2907A	BD140	TIP42C
Package	TO-92 / TO-18	TO-126 (Heatsinkable)	TO-220
$V_{CEO}$ Voltage	$-40\text{ V}$	$-80\text{ V}$	$-100\text{ V}$
Max Current ( $I_C$ )	$-600\text{ mA}$	$-1.5\text{ A}$	$-6.0\text{ A}$
Transition Freq ( $f_T$ )	$200\text{ MHz}$	$190\text{ MHz}$	$3\text{ MHz}$
Audio Linearity	Moderate	Excellent (Hi-Fi Standard)	Power Only

Common mistakes

Misidentifying the E-C-B pinout: Unlike American TO-92 transistors (E-B-C), TO-126 transistors place the Collector in the center (Emitter - Collector - Base).
Mounting to a heatsink without electrical insulation: The metal rear backing tab of the TO-126 is internally bonded to Pin 2 (Collector). In split-rail audio amplifiers, connecting the collector tab directly to an earthed heatsink will short out the negative power rail. Use a mica or sil-pad insulator and nylon mounting bushing.

Notes

Suffix Guide: -10 ( $h_{FE} = 63 \dots 160$ ) and -16 ( $h_{FE} = 100 \dots 250$ ) are the preferred gain classifications for balanced audio driver stages.

Interface	Current-Driven Base Junction
Package	SOT-32 / TO-126 (3-pin through-hole with mounting hole)