Diodes Incorporated MMDT3946-7R-F

Overview

MMDT3946-7R-F from Diodes Incorporated is a complementary NPN/PNP small-signal transistor pair in a single SOT363 package, integrating a 3904-type NPN (V_CEO = 40 V, I_C = 200 mA) and 3906-type PNP (V_CEO = −40 V, I_C = −200 mA), with h_FE up to 300 and f_T of 300 MHz (NPN) / 250 MHz (PNP), used in dual-rail biasing, level-shifting, and discrete logic interface circuits.

For engineers reviewing the MMDT3946-7R-F datasheet, MMDT3946-7R-F pinout, MMDT3946-7R-F application, or MMDT3946-7R-F equivalent, key selection criteria include complementary gain matching across temperature, ultra-small footprint for space-constrained PCBs, low V_CE(sat) (0.20 V / −0.25 V at I_C/I_B = 10), RoHS-compliant matte tin terminations, and J-STD-020 Level 1 moisture sensitivity.

Technical Context

This dual-transistor device implements two independent silicon epitaxial planar junction transistors - one NPN (3904-type) and one PNP (3906-type) - sharing no internal connection. Each transistor operates with separate base, emitter, and collector terminals, enabling fully independent biasing and switching control in push-pull, phase-splitter, or complementary amplifier topologies.

The NPN exhibits f_T = 300 MHz at V_CE = 20 V, I_C = 20 mA, while the PNP delivers f_T = 250 MHz at V_CE = −20 V, I_C = −10 mA. Both transistors support DC and pulsed operation up to 200 mW total device power dissipation, with thermal resistance R_θJA = 625 °C/W on 0.6 mm FR-4 with minimum copper pad layout.

Key Specifications

Pinout & Package

Package: SOT363 - ultra-compact 6-pin surface-mount plastic package (2.15 mm × 2.10 mm × 0.95 mm), UL 94V-0 rated, matte tin-plated terminals, 0.006 g weight, J-STD-020 Level 1 moisture sensitivity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar complementary small-signal transistor pair applications.

Compared with DMBT3946-7-F and BC846BPDW1T1G, MMDT3946-7R-F offers optimal balance of speed (300 MHz f_T), low saturation voltage, and cost-effective RoHS/Green compliance for consumer and general-purpose embedded designs.

Availability

MMDT3946-7R-F is available at Aetrix Electronics and suitable for LED driver modules, portable audio amplifiers, logic-level translators, and relay interface boards requiring stable component supply and full traceability.

Supply support for MMDT3946-7R-F 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability, industry-standard components for power management, signal integrity, and protection.

MMDT3946 belongs to Diodes' complementary transistor family designed for space-constrained, dual-rail analog and digital interface applications where matched NPN/PNP characteristics and green compliance are essential.

FAQ

What is the maximum continuous power dissipation for MMDT3946-7R-F?

The total device power dissipation is rated at 200 mW under standard conditions: mounted on minimum recommended pad layout on a single-sided 0.6 mm FR-4 PCB, measured in still air at T_A = +25°C. Derating begins linearly above +25°C at 0.32 mW/°C, reaching zero at +150°C.

Can MMDT3946-7R-F replace two discrete SOT23 transistors in existing designs?

Yes - the SOT363 footprint matches the combined area of two adjacent SOT23 devices, and pin assignments (E1/B1/C1/E2/B2/C2) follow industry-standard complementary pair layout. No PCB redesign is needed if pad spacing aligns with Diodes' suggested SOT363 layout (C = 0.65 mm, e = 0.65 mm).

Does MMDT3946-7R-F meet automotive qualification standards?

No - the standard MMDT3946-7R-F is not AEC-Q101 qualified. Diodes offers the automotive-compliant variant MMDT3946Q under a separate datasheet, which includes extended temperature screening, enhanced reliability testing, and PPAP documentation support.

How does the h_FE matching between NPN and PNP sections compare across temperature?

Both transistors exhibit parallel h_FE vs. temperature curves: h_FE decreases ~0.5%/°C above +25°C and increases ~0.7%/°C below, maintaining within ±20% tracking from −55°C to +150°C per DS30123 Rev.15 Figures 8 and 12, enabling stable complementary bias in wide-temperature environments.