Nexperia USA Inc. PMST5550,135

Overview

PMST5550 from Nexperia is an NPN high-voltage transistor in SOT323 (SC-70) package, rated for 140 V V_CEO, 300 mA I_C, and 60 minimum h_FE at 1 mA, designed for switching and amplification in telephony line interface circuits.

For engineers reviewing the PMST5550 datasheet, PMST5550 pinout, PMST5550 application, or PMST5550 equivalent, key selection criteria include high-voltage capability (140 V), low-current operation (≤300 mA), SC-70 footprint compatibility, and verified thermal resistance (625 K/W) on FR4 PCBs.

Technical Context

This discrete NPN bipolar junction transistor operates with open-base collector-emitter breakdown up to 140 V and supports pulsed peak collector current of 600 mA. Its DC current gain ranges from 60 (at 1 mA) to 250 (at 10 mA), with saturation voltage as low as 150 mV at I_C = 10 mA / I_B = 1 mA.

Thermal performance is defined for FR4 PCB mounting: junction-to-ambient thermal resistance is 625 K/W, and maximum junction temperature is 150 °C. Cut-off currents are tightly specified - ICBO ≤ 100 nA at 25 °C and ≤ 100 µA at 100 °C - supporting stable high-voltage biasing.

Key Specifications

Pinout & Package

SOT323 (SC-70) plastic surface-mounted package: 3-pin, 1.3 mm pitch, 2.0 mm × 1.25 mm × 0.95 mm body, optimized for space-constrained telephony and signal interface PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN high-voltage transistor applications.

Compared with BC846B and MMBT5551, the PMST5550 uniquely balances 140 V capability, SOT323 compactness, and controlled leakage - making it optimal for space-constrained, high-voltage telephony modules where footprint and voltage margin are co-critical.

Availability

PMST5550 is available at Aetrix Electronics and suitable for telephone line interface, ring detection, off-hook monitoring, and DC loop supervision requiring stable component supply and consistent SOT323 packaging.

Supply support for PMST5550 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

Nexperia is a global semiconductor expert focused on essential efficiency technologies, delivering high-performance, reliable discrete and logic devices for automotive, industrial, and consumer markets.

The PMST5550 belongs to Nexperia's high-voltage bipolar transistor product line, engineered specifically for analog signal conditioning and switching in legacy and VoIP telephony infrastructure where voltage resilience and small-footprint reliability are critical.

FAQ

What is the maximum continuous collector current for PMST5550?

The PMST5550 has a maximum continuous collector current (I_C) of 300 mA at T_amb ≤ 25 °C on FR4 PCB. Derating applies above 25 °C ambient per its 625 K/W thermal resistance - e.g., usable I_C drops to ~150 mA at 75 °C ambient.

Is PMST5550 suitable for automotive applications?

No. The PMST5550 is explicitly marked as non-automotive qualified in its revision history (v.5, October 2024). It lacks AEC-Q101 qualification and is not tested to automotive temperature, reliability, or stress standards.

What is the base-emitter saturation voltage at typical operating conditions?

V_BE(sat) is 1.0 V maximum at I_C = 10 mA and I_B = 1 mA, and 1.2 V maximum at I_C = 50 mA and I_B = 5 mA (pulsed, T_amb = 25 °C), defining required base drive headroom for full saturation.

How does PMST5550 compare to PMST5551 in pinout and function?

PMST5551 is the PNP complement to PMST5550 - identical SOT323 package and pinout (1=B, 2=E, 3=C), but opposite polarity. They are designed for complementary pair use in push-pull or differential stages, not as direct substitutes.