Diodes Incorporated MMST5401-7

Overview

MMST5401-7 from Diodes Incorporated is a PNP small-signal surface-mount transistor in SOT-323 package, rated for V_CEO = −150 V, I_C = −200 mA, and P_D = 200 mW. It delivers h_FE = 50–240 at I_C = −1.0 to −50 mA and f_T ≥ 100 MHz, enabling medium-power switching and amplification in space-constrained DC-DC bias networks and signal inversion stages.

For engineers reviewing the MMST5401-7 datasheet, MMST5401-7 pinout, MMST5401-7 application, or MMST5401-7 equivalent, key selection criteria include its high-voltage PNP capability, SOT-323 thermal resistance (R_JA = 625 °C/W), low V_CE(SAT) (−0.2 V @ −10 mA/−1 mA), complementary pairing with MMST5551, and RoHS-compliant lead-free plating.

Technical Context

This epitaxial planar PNP transistor operates in linear amplification and saturated switching modes, with breakdown ratings supporting −150 V collector-emitter blocking and −5.0 V emitter-base reverse tolerance. Its f_T range (100–300 MHz) and h_fe = 40–200 at 1 mA enable RF preamp and broadband switching up to ~100 MHz.

Thermal derating follows a defined curve: maximum power drops linearly from 200 mW at 25 °C ambient to zero at 150 °C, based on FR-4 PCB mounting per AP02001 layout. C_obo = 6.0 pF at −10 V V_CB supports stable high-frequency biasing without parasitic resonance.

Key Specifications

Pinout & Package

Package: SOT-323 - ultra-small surface-mount plastic case (2.0 × 1.25 × 0.9 mm), UL 94V-0 rated, moisture sensitivity Level 1, matte tin lead finish over Alloy 42 leadframe.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT5401 and BC807-40, MMST5401-7 uniquely balances −150 V blocking, SOT-323 miniaturization, and 100+ MHz bandwidth-making it the sole option for high-voltage, space-constrained switching where thermal mass is intentionally minimized.

Availability

MMST5401-7 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, isolated DC-DC converter bias networks, RF front-end preamplifiers, and compact logic-level translation circuits requiring stable component supply and long-term manufacturability.

Supply support for MMST5401-7 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, headquartered in Plano, Texas, with design centers across Asia and manufacturing in China, Taiwan, and Malaysia.

The MMST5401 belongs to Diodes' small-signal transistor product line, engineered specifically for high-voltage, low-power switching and amplification in space-constrained industrial and communications equipment.

FAQ

What is the maximum safe operating voltage for MMST5401-7 in common-emitter configuration?

The absolute maximum collector-emitter voltage (V_CEO) is −150 V at T_A = 25 °C. Derating is required above 25 °C ambient: voltage rating decreases linearly to −120 V at 100 °C. Operation must remain within the Safe Operating Area (SOA) boundary defined by simultaneous V_CE, I_C, and P_D limits shown in Figure 1 of DS30170 Rev. 6-2.

Can MMST5401-7 be used as a direct replacement for BC856 in SOT-323 footprint designs?

No. BC856 has V_CEO = −65 V and h_FE = 110–220, making it unsuitable for −150 V applications. While both are SOT-323 PNP transistors, MMST5401-7's higher breakdown voltage and broader gain range require circuit-level verification of bias stability and SOA compliance before substitution.

Does MMST5401-7 support lead-free reflow soldering per JEDEC J-STD-020?

Yes. The device uses matte tin plating over Alloy 42 leadframe and is qualified for lead-free reflow per JEDEC J-STD-020C Level 1 (peak temperature 260 °C, 10-second dwell). No special pre-bake is required due to its Level 1 moisture sensitivity rating.

How does the SOT-323 package affect thermal performance compared to SOT-23?

SOT-323 has higher thermal resistance: R_JA = 625 °C/W versus ~350 °C/W for SOT-23 on identical FR-4 layout. This means a 100 mW dissipation raises junction temperature ~62.5 °C above ambient in SOT-323, limiting continuous use to lower-power applications unless enhanced copper pour or forced airflow is applied.