Introduction
The BD434 is a silicon epitaxial-base PNP medium-power transistor engineered for linear amplification and switching applications. It belongs to a complementary pairing family, designed to work alongside NPN devices like BD433 in push-pull and audio output stages. Its PNP polarity enables it to handle negative-half cycles or high-side switching in amplifier circuits.

This transistor is housed in a TO-126 (SOT-32 / JEDEC SOT-32) plastic package, offering moderate thermal dissipation when mounted on a heatsink or circuit board. Its construction delivers good balance among gain, saturation voltage, and robustness, making it suitable for moderate-power circuits.
BD434 PNP Transistor

In practice, BD434 is widely used in audio amplifier output stages, complementary driver circuits, and general power switching roles where symmetrical PNP conduction is needed. Because it complements BD433 (its NPN counterpart), it ensures symmetrical performance in push-pull layouts, helping to reduce distortion and balance output.
Pinout of BD434

Key Features
- PNP polarity for negative conduction / high-side switching
- Matched for complementary pairing with NPN devices
- Reliable performance in moderate-power amplifier / driver circuits
- Plastic package suitable for moderate heatsinking
- Good thermal and mechanical stability
- Widely used in audio and push-pull applications
Specifications/Characteristics
- Collector-Base Breakdown Voltage, VCBO = –22 V
- Collector-Emitter Breakdown Voltage, VCEO = –22 V
- Collector-Emitter Sustaining Voltage, VCE(sus) = –22 V
- Emitter-Base Breakdown Voltage, VEBO = –5 V
- Collector Current, Continuous IC = –4 A
- Collector Peak (Pulse) Current, ICM = –7 A
- Total Power Dissipation, Ptot = 36 W (case temperature = 25 °C)
- Maximum Junction Temperature, Tj = 150 °C
- Storage Temperature Range, Tstg = –65 to +150 °C
- DC Current Gain, hFE = 85 (at IC = 0.5 A)
- DC Current Gain, hFE = 40 (at IC = 10 mA)
- DC Current Gain, hFE = 50 (at IC = 2 A)
- Collector-Emitter Saturation Voltage, VCE(sat) = –0.58 V (IC = –2 A, IB = –0.2 A)
- Base-Emitter On Voltage, VBE(on) ≈ –1.1 to –1.2 V
- Transition Frequency, fT = 3 MHz
Pin Configuration
Pin# | Pin Name | Pin Description |
---|---|---|
1 | Emitter | Output / current source terminal |
2 | Collector | Main current sink terminal |
3 | Base | Control / bias input terminal |
Comparison of BD434 (PNP) vs BD433 (NPN) Complementary
- BD434 is a PNP transistor intended to complement BD433 (NPN), used in symmetrical amplifier or driver circuits. It conducts for negative polarity or high-side segments in push-pull operations.
- BD433, on the other hand, is the NPN side of the pair. It conducts positive cycles or lower-side segments in complementary stages.
- Because they are designed as complements, BD434 and BD433 share similar current, gain, power, and thermal characteristics (with reversed polarities), allowing them to operate together symmetrically in push-pull or class-AB amplifier designs.
More Circuit Layouts








Key Applications of BD434 PNP Transistor
- Push-pull amplifier output stages
- Audio amplifier driver circuits
- Complementary driver / output stage designs
- Switching / power regulation circuits requiring PNP conduction
- General-purpose PNP transistor applications in medium-power systems
NPN Complimentary Transistor
- The complementary NPN transistor for BD434 is BD433.
Equivalent Transistors of BD434 PNP Transistor
Possible equivalents or substitution options for BD434 include:
- BD436 (higher voltage PNP in same series)
- BD438 (even higher-voltage PNP sibling)
- Other PNP medium-power transistors such as TIP32C, MJE2955, or devices with matching current/voltage specs
- PNP power transistors in TO-126 / TO-220 packages with similar ratings
Datasheet of BD434 PNP Transistor
Click the following Button to download the datasheet of BD434 Transistor :
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