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Best Alternatives to MMBT3904

Package: TO-236-3, SC-59, SOT-23-3Good-Ark SemiconductorBipolar (BJT)Series: -Package: Tape & Reel (TR) Cut Tape (CT) Digi-Reel®Current - Collector (Ic) (Max): 200 mAVoltage - Collector Emitter Breakdown (Max): 40 VCurrent - Collector Cutoff (Max): 50nA

MMBT3904 is an active SOT-23 NPN small-signal BJT. Several candidates match the role, but none have verified pinout evidence here.

AI replacement insight

Electrical riskmedium

Some candidates have lower fT or current.

Package riskmedium

SOT-23 matches, pinout is missing.

Firmware risklow

Discrete BJT has no firmware.

Sourcing risklow

Kept candidates are active.

Can it be replaced directly?

Direct replacement for MMBT3904 should use only Datasheet verified or Strong match candidates; many approved options still require engineering review.

Best replacement path

Review BC817-40 first for switching loads if 100MHz fT is acceptable.

Main risk

Pinout and dynamic performance are not verified.

Recommended alternatives

3
BC817-40 package
BC817-40

Nexperia USA Inc.

Needs validationmedium risk

BC817-40 is a strong SOT-23 NPN candidate when 100MHz fT is acceptable.

View details

Alternative comparison matrix

Feature / factorMMBT3904BC817-40MMBTA06MMBTA44Compatibility / risk
PackageSOT-23SOT-23SOT-23SOT-23SOT-23 — same package; MMBTA06: same package; MMBTA44: same package; BC850B: same package
Pinout3 pins3 pins3 pins3 pins3 pins — pin functions not shown; MMBTA06: pin functions missing; MMBTA44: pin functions missing; BC850B: pin functions missing
Voltage40V45V80V400V45V / 80V / 400V — meets 1.1x rule; MMBTA06: ample margin; MMBTA44: much higher VCEO; BC850B: meets margin
Current200mA500mA500mA200mA500mA / 200mA / 100mA — higher Ic; MMBTA06: higher Ic; MMBTA44: same Ic; BC850B: derating required
ApplicationfT 300MHzfT 100MHzfT 100MHzmissingfT 100MHz / missing / fT 300MHz — not for fast RF; MMBTA06: slower part; MMBTA44: speed unknown; BC850B: speed aligned

Application & sourcing insights

Questions & answers

Verified drop-in options for MMBT3904 are limited in the current batch. Review candidates marked Strong match or Datasheet verified, and validate package, pinout, and electrical limits before committing a BOM change.