Diodes Incorporated MMST5551Q-7-F

Overview

MMST5551Q-7-F from Diodes Incorporated is a 160V NPN small-signal transistor in SOT323 package, rated for 200 mA continuous collector current, 200 mW power dissipation, and 100–300 MHz gain-bandwidth product. It delivers V_CE(sat) ≤ 0.20 V at I_C = 50 mA / I_B = 5 mA and h_FE = 80–250 across 1–50 mA, enabling low-power switching and amplification in space-constrained analog front-ends and signal conditioning circuits.

For engineers reviewing the MMST5551Q-7-F datasheet, MMST5551Q-7-F pinout, MMST5551Q-7-F application, or MMST5551Q-7-F equivalent, key selection criteria include its 160 V V_CEO, JEDEC-qualified reliability, ultra-small SOT323 footprint, and complementary pairing with MMST5401 for push-pull configurations in portable instrumentation and sensor interface stages.

Technical Context

This NPN bipolar junction transistor uses epitaxial planar die construction for stable h_FE and low leakage (I_CBO ≤ 50 nA at 120 V), supporting precision biasing and low-noise preamplification. Its f_T ≥ 100 MHz and NF ≤ 8.0 dB at 1 kHz make it suitable for RF front-end gain stages up to VHF band.

The device operates across –55°C to +150°C, with R_θJA = 625°C/W on minimum FR4 pad layout, and meets JEDEC high-reliability standards. ESD ratings include 4 kV HBM and 1 kV CDM, confirming robustness in automated assembly and field-deployed electronics.

Key Specifications

Pinout & Package

Package: SOT323 - ultra-small surface-mount plastic package (2.15 mm × 2.10 mm × 0.95 mm), moisture sensitivity level 1, matte tin-plated leads, 0.006 g weight.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC847BW and MMBT5551, MMST5551Q-7-F uniquely balances 160 V rating, SOT323 miniaturization, and JEDEC reliability-making it optimal for compact, high-voltage, and thermally constrained signal switching where alternatives compromise either voltage headroom, size, or qualification status.

Availability

MMST5551Q-7-F is available at Aetrix Electronics and suitable for portable medical sensors, industrial I/O modules, and FPGA clock buffer circuits requiring stable component supply, RoHS/Green compliance, and AEC-Q101-aligned reliability.

Supply support for MMST5551Q-7-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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and the Americas.

MMST5551Q-7-F belongs to Diodes' high-reliability small-signal transistor product line, engineered for space-efficient, low-power amplification and switching in automotive body electronics, industrial controls, and portable instrumentation.

FAQ

Is MMST5551Q-7-F pin-compatible with standard SOT323 transistors like BC847 series?

No-while both use SOT323, MMST5551Q-7-F has emitter-base-collector pinout (1-E, 2-B, 3-C), whereas BC847BW uses emitter-collector-base (1-E, 2-C, 3-B). Incorrect PCB layout causes functional failure. Always verify top-view marking and pin 1 orientation using Diodes' package drawing DS30173 Rev. 10-2, page 5.

What is the maximum allowable collector current at 100°C ambient temperature?

Derating begins at 25°C: P_D = 200 mW with R_θJA = 625°C/W. At T_A = 100°C, max power drops to 100 mW. Using V_CE(sat) ≈ 0.15 V, max I_C = 100 mW / 0.15 V ≈ 670 mA-but absolute maximum rating caps I_C at 200 mA regardless of temperature. So 200 mA remains the hard limit.

Does MMST5551Q-7-F meet AEC-Q101 requirements for automotive use?

Yes-the MMST5551Q-7-F is qualified to AEC-Q101 Rev. D for stress testing including HTGB, HTRB, and ESD. It is manufactured in IATF 16949-certified facilities and supports PPAP documentation. Note: The "Q" suffix denotes automotive qualification; non-Q variants (e.g., MMST5551-7-F) are not AEC-Q101 certified.

Can MMST5551Q-7-F replace MMBT5551 in existing SOT23 designs?

No-SOT323 (MMST5551Q-7-F) and SOT23 (MMBT5551) have different footprints, pad layouts, and thermal characteristics. Direct replacement requires PCB redesign. While electrical specs align, R_θJA increases from ~350°C/W (SOT23) to 625°C/W (SOT323), demanding stricter thermal validation in high-duty-cycle applications.