2N4403 — -40V -600mA General-Purpose PNP BJT (TO-92)

Overview

The 2N4403 (and its surface-mount version MMBT4403) is a general-purpose PNP bipolar junction transistor manufactured by onsemi, Fairchild, STMicroelectronics, and Central Semiconductor. Housed in a through-hole TO-92 plastic package with standard Emitter - Base - Collector (E-B-C) pinout, it serves as the official PNP complement to the 2N4401.

Sharing the same physical footprint and $40\text{V}$ breakdown voltage as the classic 2N3906, the 2N4403 delivers a continuous collector current rating of $-600\text{ mA}$ (three times the current of the 2N3906). Featuring a high transition frequency ( $f_T$ ) of $200\text{ MHz}$ and low saturation voltage ( $V_{CE(sat)} \le -0.4\text{V}$ at $-150\text{mA}$ ), it is the premier choice for high-side $5\text{V}/12\text{V}$ relay and lamp switching, complementary push-pull audio drivers, discrete H-bridges, and fast saturation switches.

Quick reference


Transistor Type	Higher-Current General-Purpose Silicon PNP BJT
Package	TO-92 (3-pin through-hole) / SOT-23 (MMBT4403)
Collector-Emitter Breakdown ( $V_{CEO}$ )	$-40\text{ V}$ max
Collector-Base Breakdown ( $V_{CBO}$ )	$-40\text{ V}$ max
Continuous Collector Current ( $I_C$ )	$-600\text{ mA}$ max
DC Current Gain ( $h_{FE}$ )	$100$ to $300$ ( $I_C = -150\text{mA}, V_{CE} = -2.0\text{V}$ ) / $\ge 20$ at $-500\text{mA}$
Transition Frequency ( $f_T$ )	$200\text{ MHz}$ min
Total Power Dissipation ( $P_D$ )	$625\text{ mW}$ ( $T_A = 25^\circ\text{C}$ )
Complementary NPN Pair	2N4401 (40V 600mA NPN)

Pinout (TO-92 Package - E-B-C Standard)

Looking at the flat front face with leads pointing downward:

text

        ┌─────────┐
        │  TO-92  │
        │ 2N4403  │
        └─┬───┬───┬─┘
          1   2   3
          E   B   C

Pin	Name	Type	Description
1	`EMITTER (E)`	Emitter Terminal	Emitter (Connect to positive supply rail or emitter resistor)
2	`BASE (B)`	Base Terminal	Base control input (Driven with base current via series resistor)
3	`COLLECTOR (C)`	Collector Terminal	Collector output (Connected to high-side switched DC load)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Collector-Emitter Breakdown	$V_{(BR)CEO}$	-40	—	—	V	$I_C = -1.0\text{mA}, I_B = 0$
Collector-Base Breakdown	$V_{(BR)CBO}$	-40	—	—	V	$I_C = -100\ \mu\text{A}, I_E = 0$
Emitter-Base Breakdown	$V_{(BR)EBO}$	-5.0	—	—	V	$I_E = -100\ \mu\text{A}, I_C = 0$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	30	—	—	—	$I_C = -0.1\text{mA}, V_{CE} = -1.0\text{V}$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	100	—	300	—	$I_C = -150\text{mA}, V_{CE} = -2.0\text{V}$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	20	—	—	—	$I_C = -500\text{mA}, V_{CE} = -2.0\text{V}$
Collector Saturation Voltage	$V_{CE(sat)}$	—	—	-0.40	V	$I_C = -150\text{mA}, I_B = -15\text{mA}$
Collector Saturation Voltage	$V_{CE(sat)}$	—	—	-0.75	V	$I_C = -500\text{mA}, I_B = -50\text{mA}$
Base Saturation Voltage	$V_{BE(sat)}$	-0.75	—	-0.95	V	$I_C = -150\text{mA}, I_B = -15\text{mA}$

Typical Application Circuit: High-Side 12V 400mA Solenoid Switch

text

  +12V DC Supply ─────────────────────────────────┬─────────► [Pin 1: EMITTER]
                                                  │              2N4403 (PNP)
                                           [ 10kΩ Pull-Up ]      [Pin 3: COLLECTOR] ──► [ + 400mA Load - ] ──┐
                                                  │                 │                                         │
                                                  ├─────────► [Pin 2: BASE]                                   │
                                                  │                                                           │
                                            [ COLLECTOR ]                                                     │
  MCU GPIO (3.3V / 5V) ───[ 1kΩ Resistor ]──► Base of 2N3904 (NPN)                                            │
                                            [ EMITTER ]                                                       │
                                                  │                                                           │
  Common Ground (0V) ─────────────────────────────┴───────────────────────────────────────────────────────────┴── Ground Return

Comparison: 2N4403 vs 2N3906 vs 2N2907A

Parameter	2N3906	2N4403	2N2907A
Max Current ( $I_C$ )	$-200\text{ mA}$	$-600\text{ mA}$	$-600\text{ mA}$
$V_{CEO}$ Voltage	$-40\text{ V}$	$-40\text{ V}$	$-60\text{ V}$
Gain at 150mA	Drops severely ( $< 30$ )	High ( $100 \dots 300$ )	High ( $100 \dots 300$ )
Transition Freq ( $f_T$ )	$250\text{ MHz}$	$200\text{ MHz}$	$200\text{ MHz}$
Complementary NPN	2N3904	2N4401	2N2222A

Common mistakes

Driving directly from an MCU pin on supplies above VCC_MCU: If the emitter of the 2N4403 is connected to $+12\text{V}$ , an MCU GPIO driving $+5\text{V}$ leaves $V_{EB} = 7\text{V}$ , forward-biasing the base-emitter junction and driving destructive current into the microcontroller's internal ESD protection diodes. Always use an intermediate NPN pull-down transistor or open-drain buffer for supplies $> 5\text{V}$ .

Notes

Suffix Guide: 2N4402 is a lower gain ( $h_{FE} = 50 \dots 150$ ) variant; 2N4403 is the full performance part; MMBT4403 is the SOT-23 surface-mount package.

Interface	Current-Driven Base Junction
Package	TO-92 Plastic (through-hole) / SOT-23 (MMBT4403)