Diodes Incorporated MMSTA55-7-F

Overview

MMSTA55-7-F from Diodes Incorporated is a PNP small-signal surface-mount transistor in SOT-323 package, rated for -60 V V_CEO, -500 mA I_C, 200 mW P_D, with h_FE ≥100 at -10 mA/-1.0 V, and f_T = 50 MHz - used in low-power switching and amplification stages of portable audio bias networks and LED driver current sinks.

For engineers reviewing the MMSTA55-7-F datasheet, MMSTA55-7-F pinout, MMSTA55-7-F application, or MMSTA55-7-F equivalent, key selection criteria include verified PNP polarity, SOT-323 thermal resistance (R_θJA = 625 °C/W), V_CE(SAT) ≤ -0.25 V at -100 mA/-10 mA, ESD-safe handling per J-STD-020C Level 1, and RoHS-compliant matte tin plating.

Technical Context

This discrete PNP bipolar junction transistor employs epitaxial planar die construction for stable gain and low leakage. Its complementary NPN counterpart is MMSTA05-7-F, enabling matched pair design in differential amplifiers and push-pull output stages.

Rated for operation from -55 °C to +150 °C, it delivers consistent h_FE across temperature (Fig. 3) and maintains V_BE(SAT) ≤ -1.2 V under -100 mA load, supporting reliable saturation in low-voltage logic-level switching circuits.

Key Specifications

Pinout & Package

Package: SOT-323 - ultra-small surface-mount plastic case (2.0–2.2 mm × 1.15–1.35 mm × 0.25–0.40 mm height), UL 94V-0 rated, moisture sensitivity Level 1, lead-free matte tin plating 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 BC807-40LT1G and PN2907A, MMSTA55-7-F offers optimal balance of ultra-compact SOT-323 size, guaranteed -60 V rating, and production-proven reliability in high-volume portable designs - making it preferred where board area and voltage margin are co-critical.

Availability

MMSTA55-7-F is available at Aetrix Electronics and suitable for portable audio bias networks, LED driver current sinks, and low-voltage logic-level switches requiring stable component supply and long-term manufacturing continuity.

Supply support for MMSTA55-7-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, specializing in high-reliability, cost-optimized components for consumer, industrial, and automotive markets.

The MMSTA55-7-F belongs to Diodes' small-signal transistor product line, engineered specifically for space-constrained, low-power linear and switching applications in battery-operated electronics.

FAQ

What is the maximum junction temperature for MMSTA55-7-F?

The MMSTA55-7-F has an operating junction temperature range of -55 °C to +150 °C, as specified in the Absolute Maximum Ratings table. This rating applies under continuous operation with proper PCB thermal management per Diodes Inc. AP02001 layout guidelines.

Is MMSTA55-7-F pin-compatible with MMSTA56-7-F?

Yes - both share identical SOT-323 package and pinout (Emitter-Base-Collector). However, MMSTA56-7-F has higher -80 V V_CEO/V_CBO ratings and same -500 mA I_C, making it a direct upgrade for higher-voltage applications without layout change.

Does MMSTA55-7-F require derating above 25°C ambient?

Yes - its maximum power dissipation decreases linearly above 25°C, with full derating to zero at 150°C ambient (Fig. 1). At 70°C ambient, allowable P_D drops to ~120 mW based on R_θJA = 625 °C/W and T_J(max) = 150°C.

Can MMSTA55-7-F be used in avalanche mode?

No - the device is not characterized or rated for avalanche operation. Its V_(BR)CEO = -60 V is a breakdown limit, not a controlled energy-dissipating mode. Operation beyond this voltage risks irreversible damage.