Basic Product Information
Part Number: MMBT3904LT1G
| Field |
Value |
| Manufacturer |
onsemi (formerly ON Semiconductor / Fairchild) |
| Device Type |
MMBT3904LT1G |
| Package |
SOT-23-3 (TO-236-3, SC-59), 2.90mm x 1.30mm x 1.00mm |
| Model Interpretation |
MMBT = Surface-mount general purpose BJT family, 3904 = Industry-standard NPN small-signal transistor (SMD equivalent of 2N3904), L = Lead-free / RoHS compliant, T1 = Tape & Reel packaging (10,000 pcs/reel), G = Green / Halogen-free molding compound |
| Compliance |
RoHS3 Compliant, Lead-Free, Halogen-Free (RFB), REACH Unaffected, ECCN: EAR99 |
| Grade |
Industrial; S-prefix version (SMMBT3904LT1G) qualified to AEC-Q101 for automotive |
| SMD Marking |
1AM |
| MSL Rating |
Level-1 (Unlimited floor life at 260°C peak reflow) |
Core Electrical Parameters
| Parameter |
Value |
Unit |
| Transistor Polarity |
NPN |
— |
| Collector-Emitter Voltage (VCEO) |
40 |
V |
| Collector-Base Voltage (VCBO) |
60 |
V |
| Emitter-Base Voltage (VEBO) |
6.0 |
V |
| Continuous Collector Current (IC) |
200 |
mA |
| Pulse Collector Current |
900 |
mA |
| Total Power Dissipation (PT) |
225 (FR-5 board) / 300 (ideal) |
mW |
| Thermal Resistance (RθJA) |
556 |
°C/W |
| DC Current Gain (hFE) @ IC=0.1mA, VCE=1V |
40 min |
— |
| DC Current Gain (hFE) @ IC=1mA, VCE=1V |
70 min |
— |
| DC Current Gain (hFE) @ IC=10mA, VCE=1V |
100–300 |
— |
| DC Current Gain (hFE) @ IC=50mA, VCE=1V |
60 min |
— |
| DC Current Gain (hFE) @ IC=100mA, VCE=1V |
30 min |
— |
| Collector-Emitter Saturation Voltage (VCE(sat)) @ IB=1mA, IC=10mA |
0.2 max |
V |
| Collector-Emitter Saturation Voltage (VCE(sat)) @ IB=5mA, IC=50mA |
0.3 max |
V |
| Base-Emitter Saturation Voltage (VBE(sat)) @ IB=1mA, IC=10mA |
0.65–0.85 |
V |
| Base-Emitter Saturation Voltage (VBE(sat)) @ IB=5mA, IC=50mA |
0.95 max |
V |
| Collector Cutoff Current (ICEX) @ VCE=30V, VEB=3V |
50 max |
nA |
| Base Cutoff Current (IBL) @ VCE=30V, VEB=3V |
50 max |
nA |
| Current-Gain Bandwidth Product (fT) @ IC=10mA, VCE=20V |
300 min |
MHz |
| Output Capacitance (Cobo) @ VCB=5V, f=1MHz |
4.0 max |
pF |
| Input Capacitance (Cibo) @ VEB=0.5V, f=1MHz |
8.0 max |
pF |
| Noise Figure (NF) @ VCE=5V, IC=100µA, RS=1kΩ, f=1kHz |
5.0 max |
dB |
| Switching Delay Time (td) |
35 max |
ns |
| Switching Rise Time (tr) |
35 max |
ns |
| Switching Storage Time (ts) |
200 max |
ns |
| Switching Fall Time (tf) |
50 max |
ns |
| Operating Temperature Range |
-55 to +150 |
°C (TJ) |
Core Features & Advantages
The MMBT3904LT1G is the industry’s most widely deployed NPN general-purpose small-signal transistor in SOT-23 surface-mount packaging — the direct SMD equivalent of the legendary 2N3904 through-hole transistor. Its ubiquity in modern electronics stems from a combination of reliable performance, aggressive pricing, and unmatched supply chain depth.
- Primary Function: General-purpose NPN BJT for low-power amplification and switching applications up to 300 MHz
- Key Advantages:
- Industry-Standard Pinout and Specifications: The 3904 platform has been in continuous production for over five decades. Every major semiconductor manufacturer (onsemi, Diodes Inc., Nexperia, Infineon, MCC, Diotec) produces pin-compatible equivalents, ensuring multi-source availability and eliminating sole-supplier risk in production BOMs.
- Extremely Low Procurement Cost: Volume pricing at the $0.01–$0.02 level per unit makes this one of the cheapest active components available. TI direct price: $0.0125 at 1ku. Farnell/element14: $0.019 at 5ku. This cost structure enables liberal use across signal conditioning, level shifting, and logic interface circuits without budget impact.
- Broad hFE Range (100–300) at 10mA: The wide gain spread accommodates both precision amplifier circuits (binning for matched pairs) and general-purpose switching where exact gain is non-critical. At 10mA collector current and 1V VCE, the guaranteed minimum hFE of 100 provides ample drive margin for most small-signal loads.
- 300 MHz Transition Frequency: Sufficient bandwidth for RF front-end stages, IF amplifiers, and oscillator circuits well into the VHF range. The combination of low output capacitance (4.0 pF max Cobo) and high fT makes the MMBT3904LT1G suitable for small-signal RF applications up to approximately 100 MHz in practical circuits.
- Low Leakage and Low Noise: Collector cutoff current of only 50 nA maximum and noise figure of 5.0 dB maximum at 1 kHz ensure clean signal handling in sensitive analog paths such as sensor interfaces, microphone preamplifiers, and medical instrumentation front-ends.
- Compact SOT-23 with MSL-1 Rating: The 2.9mm x 1.3mm footprint occupies minimal board area in high-density designs. MSL-1 (unlimited floor life) eliminates bake-out requirements before reflow soldering, simplifying SMT production logistics for this high-volume component.
Typical Application Scenarios
- Industry: Consumer Electronics / Industrial Control / Automotive (S-prefix version) / Medical Devices / Telecommunications / IoT
- Equipment: Signal conditioning circuits, LED driver switches, logic-level translators, sensor interface amplifiers, relay drivers, DC-DC converter feedback networks, oscillator circuits, audio preamplifiers
- Use Cases:
- General-purpose low-side switching for indicator LEDs, small relays, and buzzer drivers where 200 mA collector current is sufficient — the MMBT3904LT1G replaces MOSFETs in cost-sensitive designs where gate drive voltage is readily available from logic outputs
- Signal amplification and buffering in sensor acquisition chains (thermistors, photodiodes, strain gauges) where the low 50 nA leakage current and 5.0 dB noise figure preserve signal integrity
- Level shifting and voltage translation between 3.3V and 5V logic domains in mixed-voltage systems, exploiting the 40V VCEO rating for wide voltage margin
- RC oscillator and crystal oscillator circuits requiring a general-purpose NPN device with 300 MHz fT and predictable hFE for stable oscillation conditions
Market Reference Price
| Market |
Price Range |
Currency |
| Huaqiangbei Spot |
$0.005 – $0.015 |
USD |
| Overseas B2B |
$0.012 – $0.120 |
USD |
Note: This is one of the lowest-cost active components in the industry. onsemi direct pricing: $0.0125/pc at 1ku (10,000-reel). DigiKey: 1pc $0.12, 3,000pc $0.024/pc. Farnell/element14: $0.019/pc at 5ku. Huaqiangbei spot market pricing can reach sub-cent levels for bulk orders but authenticity verification is essential. Device is in Active/Production status with no supply risk — global distributor inventory exceeds 120 million units. Contact suppliers for volume discounts.
Related Models Comparison
| Model |
Difference |
Target Application |
| MMBT3904LT3G |
Same die, 3,000 pcs/reel (vs. 10,000 for T1G); unit pricing slightly higher at lower volumes |
Small-to-medium volume production where 3k reel is preferred |
| SMMBT3904LT1G |
Automotive AEC-Q101 qualified version; identical electrical specs; qualified to Grade 1 (-40°C to +125°C ambient); higher unit price ($0.0123 vs $0.0125 at 1ku) |
Automotive applications requiring AEC-Q101 compliance (ECUs, body electronics, sensor interfaces) |
| MMBT3904-7-F |
Diodes Inc. second-source equivalent; slightly higher power dissipation (310 mW vs 225 mW); pin-compatible; slightly higher unit cost |
Multi-source BOM designs where Diodes Inc. is an approved vendor |
| MMBT2222A |
Higher current capability (600 mA IC); higher VCEO (75V); lower fT (300 MHz typical but wider gain spread); same SOT-23 package |
Applications requiring higher collector current or voltage than MMBT3904 can provide |
| PMBT3904 (Nexperia) |
Nexperia (formerly NXP) second-source; virtually identical specifications; different hFE binning options available |
BOMs specifying Nexperia as preferred vendor |
| 2N3904 |
Through-hole TO-92 equivalent; identical electrical characteristics; 625 mW power dissipation (higher due to larger package); not surface-mount |
Prototyping, breadboarding, and legacy through-hole designs |
| BC847C |
Higher hFE (420–800 at 2mA); lower VCEO (45V); lower noise; same SOT-23 package; different pinout (EBC vs CBE for MMBT3904) |
Low-noise amplifier stages requiring higher gain; note pinout difference requires PCB change |
