MMBT3904-AQ - 40V NPN BJT, 200mA, SOT-23, AEC-Q101 | Diotec
MPN: MMBT3904-AQ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.18 | $0.18 |
| 10 | $0.16 | $1.60 |
| 100 | $0.12 | $12.00 |
| 500 | $0.09 | $45.00 |
| 1,000 | $0.07 | $70.00 |
MMBT3904-AQ Overview
A small-signal NPN BJT (bipolar junction transistor) is a three-terminal semiconductor device in which a small base current controls a much larger collector current, enabling both linear amplification and saturated switching. Within the broader component taxonomy, the MMBT3904 family sits under small-signal transistor -> BJT -> discrete semiconductor. The MMBT3904-AQ is the AEC-Q101-qualified derivative of the industry-standard MMBT3904, adding automotive-grade reliability screening, extended operating temperature range, and PPAP documentation to the classic MMBT3904 footprint and pinout.
Key features include a 40 V collector-emitter breakdown voltage (VCEO), 60 V collector-base breakdown voltage (VCBO), 6 V emitter-base breakdown voltage (VEBO), 300 MHz transition frequency (fT) measured at Vce=20 V and IC=10 mA, and DC current gain (hFE) of 100 to 300. The SOT-23 (TO-236) surface-mount package supports automated assembly and reflow soldering, while the AEC-Q101 qualification makes the part eligible for automotive electronics, industrial controls, and other high-reliability applications.
The device uses an epitaxial planar die construction, providing tight parametric distribution, low noise figure, and stable gain across the operating temperature range. As the NPN complement to the MMBT3906, the MMBT3904-AQ is widely used in complementary push-pull output stages, level shifters, and driver circuits for MOSFETs, IGBTs, and relay coils. The high fT and fast switching characteristics also enable RF small-signal stages and high-speed logic interface designs.
Typical applications include automotive body and chassis electronics, sensor signal conditioning, MOSFET/relay drivers, DC-DC converter control loops, level shifting between logic domains, general-purpose switching circuits, and small-signal amplification in industrial and consumer designs. The combination of 40 V rating, 200 mA collector current, and AEC-Q101 qualification covers most 12 V/24 V automotive bus applications.
When designing with the MMBT3904-AQ, observe the 350 mW power dissipation limit and derate appropriately at elevated ambient temperatures. Place base resistor and collector load components close to the device to minimize parasitic inductance, and verify that saturation and switching specifications are met under worst-case base drive conditions.
This page synthesizes distributor pricing across three channels, plug-compatible alternatives - cross-brand variants sourced from verified cross-reference data, and practical design notes not aggregated on the manufacturer product page.
Drop-in alternatives for MMBT3904-AQ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MMBT3904-AQ (same form factor and footprint) — differing in DC Current Gain (hFE), Transition Frequency (fT), Collector-Base Voltage (VCBO), Transistor Type, Operating Temperature Range.
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View Datasheet →MMBT3904-AQ Maximum Ratings & Electrical Characteristics
| Transistor Type | NPN |
| Package | SOT-23-3 (TO-236) |
| Mounting Type | Surface Mount |
| Collector-Emitter Voltage (Vceo) | 40 V |
| Collector-Base Voltage (Vcbo) | 60 V |
| Emitter-Base Voltage (Vebo) | 6 V |
| Continuous Collector Current (IC) | 200 mA |
| Power Dissipation (Pd) | 350 mW |
| Transition Frequency (ft) | 300 MHz (at VCE=20V, IC=10mA) |
| DC Current Gain (hFE) | 100 to 300 |
| Operating Temperature | -55C to +150C |
| Automotive Qualification | AEC-Q101 |
| RoHS Status | Compliant |
| Pin Configuration | Pin 1: Base, Pin 2: Emitter, Pin 3: Collector |
| Die Construction | Epitaxial planar |
MMBT3904-AQ Pin Configuration
| Pin 1 | Base — Control input - base current controls collector current |
| Pin 2 | Emitter — Emitter terminal (typically grounded or at lower potential) |
| Pin 3 | Collector — Collector terminal - main current path |
Typical Applications
MMBT3904-AQ is suitable for 7 applications: Automotive Sensor Signal Conditioning, MOSFET and Relay Driver, Logic Level Shifter, DC-DC Converter Control Loop, General-Purpose Switching Circuit, Small-Signal RF Amplifier, Complementary Push-Pull Output Stage.
Automotive Sensor Signal Conditioning
The MMBT3904-AQ is well suited for automotive sensor signal conditioning circuits where AEC-Q101 qualification is mandatory. The 300 MHz transition frequency preserves signal integrity for sensor bandwidths up to several MHz, while the 40V VCEO and 200mA collector current provide ample headroom for 12V/24V automotive bus interfaces. The high DC current gain (100-300) enables direct interface to low-current sensor outputs without additional driver stages. Placed at the front-end of a sensor amplifier with a base-bias resistor network, the -AQ variant adds automotive reliability to a standard MMBT3904 design with no PCB changes.
Recommended
MOSFET and Relay Driver
The MMBT3904-AQ serves as an effective low-side driver for small MOSFETs, IGBTs, and relay coils in automotive and industrial systems. With 200mA collector current capability and 40V VCEO, the device can sink typical logic-MOSFET gate currents directly or drive small relay coils through a base resistor. The AEC-Q101 qualification makes the part suitable for under-hood and chassis driver designs, and the SOT-23-3 footprint enables high-density driver arrays. For higher coil currents or PWM switching, pair the -AQ stage with a power MOSFET such as the Diotec DMP3098L.
Recommended
Logic Level Shifter
The MMBT3904-AQ functions as a compact logic level shifter between low-voltage microcontrollers (3.3V/1.8V) and 5V/12V automotive or industrial buses. The emitter-follower or common-emitter configurations both work well with this part due to its 300 MHz fT, which supports high-speed logic translation. The 40V VCEO provides headroom for 24V bus translation, and the 6V VEBO requires a base-clamping diode when driven by 5V logic with inductive loads. The AEC-Q101 qualification makes the -AQ variant the preferred choice for automotive ECU signal interfacing.
Recommended
DC-DC Converter Control Loop
In small isolated or non-isolated DC-DC converter control loops, the MMBT3904-AQ acts as an error amplifier or PWM driver transistor. The 300MHz fT ensures adequate bandwidth for switching frequencies up to several hundred kHz typical of small converters, while the 40V/200mA ratings handle most 12V/24V input rails. The AEC-Q101 qualification extends the part's use into automotive power supply designs for body controllers and sensor modules. Place the -AQ in the feedback network with appropriate compensation to maintain loop stability across temperature.
Recommended
General-Purpose Switching Circuit
The MMBT3904-AQ is a versatile general-purpose switch for indicator LED drivers, small solenoid drivers, and interface circuits. With a saturation voltage of typically 200mV at 50mA collector current and switching times in the nanosecond range, the -AQ variant handles most low-frequency switching tasks. The AEC-Q101 qualification makes the part suitable for automotive interior lighting, indicator drivers, and dashboard electronics where reliability data is required. The SOT-23 footprint and 350mW dissipation support high-density PCB layouts.
Recommended
Small-Signal RF Amplifier
The MMBT3904-AQ operates effectively as a small-signal RF amplifier for frequencies up to approximately 100 MHz in practical designs, well within its 300 MHz transition frequency. The low noise figure (typically 5 dB maximum at the rated operating point) and high DC current gain make it suitable for low-noise input stages in receivers, RF mixers, and IF amplifiers. The AEC-Q101 qualification supports automotive RF applications including keyless entry, tire pressure monitoring, and V2X transceivers. Place the -AQ in a properly impedance-matched network to realize the full bandwidth capability.
Recommended
Complementary Push-Pull Output Stage
Paired with the PNP MMBT3906-AQ, the MMBT3904-AQ forms a classic complementary push-pull amplifier stage for audio, motor drive, and power-conversion output stages. The matched hFE and transition frequency of the NPN/PNP pair ensure symmetric switching and low crossover distortion, while the 40V/200mA ratings handle most low-power output applications. The AEC-Q101 qualification of both halves extends the topology to automotive audio amplifiers, small motor drivers, and complementary driver stages in industrial designs.
Recommended
Recommended Products Summary
Engineering reference data for MMBT3904-AQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MMBT3904 | MMBT3904LT1G | MMBT3904-TP | MMBT3904-7-F | MMBT3904 |
|---|---|---|---|---|---|---|
| Brand | Diotec Semiconductor | Diotec Semiconductor | onsemi | Micro Commercial Components | Diodes Incorporated | Good-Ark Semiconductor |
| Package | SOT-23-3 (TO-236) | SOT-23-3 (TO-236) - same | SOT-23-3 (TO-236) - same | SOT-23-3 (TO-236) - same | SOT-23-3 (TO-236) - same | SOT-23-3 (TO-236) - same |
| Transistor Type | NPN | NPN | NPN | NPN | NPN | NPN |
| VCEO (V) | 40 V | 40 V | 40 V | 40 V | 40 V | 40 V |
| Collector Current (mA) | 200 mA | 200 mA | 200 mA | 200 mA | 200 mA | 200 mA |
| Power Dissipation (mW) | 350 mW | 350 mW | 225 mW (lower) | 350 mW | 350 mW | 200 mW (lower) |
| Transition Frequency (MHz) | 300 MHz | 300 MHz | 300 MHz | 300 MHz | 300 MHz | 300 MHz |
| DC Current Gain (hFE) | 100 to 300 | 100 to 300 | 100 to 300 | 100 to 300 | 100 to 300 | 100 to 300 |
| AEC-Q101 Qualified | Yes | No (commercial) | No (commercial) | No (commercial) | No (commercial) | No (commercial) |
| Operating Temperature | -55C to +150C | -55C to +150C | -55C to +150C | -55C to +150C | -55C to +150C | -55C to +150C |
Key Differentiators
- AEC-Q101 automotive qualification with full PPAP (vs MMBT3904 (Diotec, non-automotive))
- 350mW power dissipation rating (vs Good-Ark MMBT3904)
- Standard JEDEC SOT-23 pinout across full MMBT3904 family (vs Cross-brand alternatives (onsemi, Diodes Inc, MCC))
Design Notes
Estimated: at maximum rated collector current of 200mA with VCE at saturation (~200mV), the device dissipates approximately 40mW - well below the 350mW absolute maximum. However, at higher VCE values such as 30V (linear operation), power dissipation reaches 6W if 200mA is forced, far exceeding the package capability. Always operate the MMBT3904-AQ in either full saturation (switching) or in the linear region with collector current limited to a safe value per Pd/VCE derating curves. For continuous operation above 100mA, provide at least 100mm^2 of copper pour on the collector lead pad to lower junction-to-ambient thermal resistance below the JEDEC 2oz 1-inch-square reference.
The SOT-23-3 footprint is JEDEC standard; pin 1 is Base, pin 2 is Emitter, and pin 3 is Collector when viewed from above with the marking dot at the top-left. Place base bias resistors within 5mm of the base pin to minimize parasitic oscillation risk at high frequencies. The collector pad can be extended with thermal vias to a copper pour on the opposite PCB side for additional heatsinking. Do not route noisy digital or switching traces under the collector pad - the exposed thermal mass can couple switching transients into sensitive analog stages.
Do not exceed the 6V emitter-base breakdown voltage (VEBO) - reverse-biasing the base-emitter junction above this value (which can happen during inductive load switching without a flyback path) destroys the transistor. Add a base-emitter resistor (typically 10k) when the base is driven from a high-voltage node that could be reversed, and place a flyback diode across inductive loads. Also, verify that the 60V collector-base rating is not exceeded during inductive turn-off transients - even brief overshoots can degrade the junction. The AEC-Q101 qualification of the -AQ variant does not relax any of these electrical limits; it only documents that the part is screened to automotive stress profiles.
Compliance Information
RoHS compliant per Diotec product page and OnlineComponents listing. AEC-Q101 qualified (suffix -AQ denotes automotive grade). Lead-free reflow compatible per JEDEC J-STD-020.