BF422 NPN Transistor TO-92
The BF422 is a high-voltage NPN transistor supplied in a TO-92 plastic package, engineered for applications that require substantial collector-emitter voltage handling in a compact through-hole form. Its rugged construction and thermal characteristics let it tolerate elevated junction temperatures and high voltages while remaining suitable for consumer and professional electronics.
Electrically, the BF422 is optimized for tasks such as video output and general high-voltage switching: it offers a collector-emitter breakdown rating and collector-base rating up to the datasheet limits, conservative continuous collector current capability, and moderate collector dissipation. These attributes let designers use it in stages that must drive moderate currents at relatively high voltages without resorting to larger packages.
Mechanically packaged in the standard TO-92 outline with three leads (emitter, collector, base), the BF422 is easy to prototype on perfboard or integrate into PCBs with simple pad layouts. Its balance of voltage rating, gain, transition frequency, and low feedback capacitance make it a compact choice where footprint, cost and moderate performance are priorities.
Features:
- High collector-base and collector-emitter breakdown voltages.
- Low feedback capacitance for improved high-frequency performance.
- Packaged in space-saving TO-92 plastic.
- Suitable complements available (BF421/BF423) for complementary stages.
- Moderate DC current gain (hFE at specified conditions).
- Designed for Class-B video output and similar high-voltage stages.
Specifications:
| Specification | Detail |
|---|---|
| Part number: | BF422 (NPN, TO-92) |
| Collector-Base breakdown V(BR)CBO: | 250 V |
| Collector-Emitter breakdown V(BR)CEO: | 250 V |
| Emitter-Base breakdown V(BR)EBO: | 5 V |
| Collector continuous current (IC): | 100 mA |
| Collector power dissipation (Pc): | ≈ 0.83 W |
| Thermal resistance, RthJA: | 151 °C/W |
| DC current gain (hFE): | ≈ 50 (VCE = 20 V, IC = 25 mA) |
| VCE(sat): | ≈ 0.6 V (IC = 30 mA, IB = 5 mA) |
| Transition frequency (fT): | ≈ 60 MHz (VCE = 10 V, IC = 10 mA) |
| Feedback capacitance (Cre): | ≈ 1.6 pF (VCE = 30 V, IC = 0, f = 1 MHz) |
| Collector cutoff (ICBO) / Emitter cutoff (IEBO): | ICBO ≈ 0.01 µA (VCB = 200 V); IEBO ≈ 0.05 µA (VEB = 5 V) |
| Operating / Storage temp.: | −55 °C to +150 °C |
| Package: | TO-92 plastic (3-lead) |
Pinout Diagram:

Footprint Diagram:

Applications:
- Class-B video output stages.
- High-voltage switching.
- General-purpose amplifier stages.
- Complementary push-pull output stages (with BF421/BF423).
Package Contents:
- 1x BF422 NPN Transistor TO-92



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