onsemi MMBT3906K

Overview

MMBT3906K from Fairchild Semiconductor is a PNP epitaxial silicon general-purpose transistor in SOT-23 package, rated for −40 V V_CEO, −200 mA I_C, 350 mW P_C, with h_FE = 60–300 at I_C = −0.1 to −100 mA, and f_T = 250 MHz. It serves as a low-power switching or linear amplification device in bias networks, level shifters, and discrete logic interfaces.

For engineers reviewing the MMBT3906K datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP polarity, SOT-23 terminal mapping (1=Base, 2=Emitter, 3=Collector), guaranteed −40 V breakdown ratings, h_FE min/max across five collector current points, and 250 MHz f_T performance under standard test conditions.

Technical Context

The MMBT3906K is a discrete bipolar junction transistor with epitaxial base construction, optimized for general-purpose linear and switching operation. Its DC current gain spans 60–300 depending on I_C (−0.1 mA to −100 mA) and V_CE = −1 V, and it delivers V_CE(sat) ≤ −0.4 V at I_C = −50 mA / I_B = −5 mA.

It exhibits t_ON = 70 ns and t_OFF = 300 ns under defined resistive-switching conditions (V_CC = −3 V, I_C = −10 mA), with Cob = 4.5 pF at V_CB = −5 V and NF = 4 dB in audio-band noise testing (I_C = −100 µA, V_CE = −5 V, R_S = 1 kΩ).

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads; 1.90 mm × 1.30 mm footprint, 1.14 mm max height, and 0.95 mm lead pitch. Marked "2AK" on top surface.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose transistor applications.

Compared with BC807-40 and PN2907A, the MMBT3906K offers balanced gain-bandwidth trade-off and SOT-23 compatibility for space-constrained automated assembly, while maintaining broad bias flexibility across −0.1 mA to −100 mA operating range.

Availability

MMBT3906K is available at Aetrix Electronics and suitable for LED driver circuits, level-shifting interfaces, discrete logic inverters, and current mirror references requiring stable component supply and consistent parametric performance.

Supply support for MMBT3906K includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The MMBT3906K belongs to Fairchild's general-purpose bipolar transistor product line, designed for cost-sensitive, high-volume applications requiring reliable DC switching and linear amplification in consumer, industrial, and computing equipment.

FAQ

What is the pin configuration of the MMBT3906K?

The MMBT3906K uses a standard SOT-23 package with pin 1 as Base, pin 2 as Emitter, and pin 3 as Collector. This configuration is confirmed in the official Fairchild MMBT3906K Rev. B datasheet mechanical drawing and marking diagram. The top-side marking "2AK" identifies the device and aligns with this pinout. No alternate pin mappings are documented for the MMBT3906K.

Does the MMBT3906K support switching at 1 MHz?

Yes, the MMBT3906K supports reliable 1 MHz switching in common-emitter configurations. Its t_ON = 70 ns and t_OFF = 300 ns enable clean transitions at this frequency, and its f_T = 250 MHz confirms sufficient gain-bandwidth for stable closed-loop behavior. Real-world performance depends on proper base drive strength and load impedance, but the MMBT3906K datasheet validates operation under these conditions.

What is the minimum h_FE of the MMBT3906K at I_C = −10 mA?

The minimum h_FE of the MMBT3906K at I_C = −10 mA and V_CE = −1 V is 100, as specified in the Electrical Characteristics table of the Fairchild MMBT3906K Rev. B datasheet. This value is guaranteed across the operating temperature range and forms the basis for conservative bias network design. The MMBT3906K also guarantees h_FE ≥ 60 at I_C = −100 mA, supporting wide dynamic range use.

Can the MMBT3906K replace the MMBT3904 in a circuit?

No, the MMBT3906K cannot directly replace the NPN MMBT3904 because they have opposite polarity: MMBT3906K is PNP while MMBT3904 is NPN. Swapping them would invert logic states and likely cause circuit failure. To substitute, redesign the bias network and signal path - for example, flipping supply connections and inverting control signals. The MMBT3906K and MMBT3904 share the same SOT-23 package and pinout order, but their electrical roles are complementary, not interchangeable.

Is the MMBT3906K RoHS compliant?

Yes, the MMBT3906K is RoHS compliant. Fairchild Semiconductor declared RoHS compliance for the MMBT3906K family prior to its acquisition by ON Semiconductor, and the Rev. B datasheet reflects lead-free SOT-23 packaging and termination. All currently distributed MMBT3906K units meet EU Directive 2011/65/EU requirements, including restrictions on lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE.