Nexperia USA Inc. PMST5550-QX

Overview

PMST5550-QX from Nexperia is an AEC-Q101-qualified NPN high-voltage transistor in SOT323 (SC-70) package, rated for 140 V V_CEO, 300 mA I_C, and 20–250 h_FE at 50 mA. It serves as a switching or amplification device in space-constrained, high-voltage telephony circuits operating up to 150 °C junction temperature.

For engineers reviewing the PMST5550-QX datasheet, PMST5550-QX pinout, PMST5550-QX application, or PMST5550-QX equivalent, key selection criteria include its automotive-grade qualification, low thermal resistance (625 K/W), 6 pF collector capacitance, and verified performance under pulsed conditions (t_p ≤ 300 µs, δ ≤ 0.02).

Technical Context

This discrete NPN bipolar junction transistor operates with open-base collector-emitter breakdown of 140 V and open-emitter collector-base rating of 160 V, enabling robust high-voltage switching in telephony line interface units. Its DC current gain spans 20–250 across 1–50 mA I_C, with V_CE(sat) ≤ 250 mV at I_C = 50 mA / I_B = 5 mA.

Thermal design is constrained by 200 mW total power dissipation on FR4 PCB (single-sided copper, tin-plated), yielding 625 K/W junction-to-ambient resistance. Noise figure is specified at 8 dB (10 Hz–15.7 kHz, R_S = 2 kΩ), supporting low-noise analog amplification roles in signal conditioning stages.

Key Specifications

Pinout & Package

Package: SOT323 (SC-70), plastic surface-mounted, 3-lead, 1.3 mm pitch, 2.0 × 1.25 × 0.95 mm body size.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC846B,215 and MMBT5551, PMST5550-QX uniquely balances 140 V blocking, AEC-Q101 qualification, and SOT323 miniaturization-making it optimal for space- and reliability-critical high-voltage automotive and telecom edge nodes.

Availability

PMST5550-QX is available at Aetrix Electronics and suitable for telephony line interfaces, automotive body control modules, industrial sensor signal conditioning, and medical equipment power sequencing requiring stable component supply and long-term lifecycle assurance.

Supply support for PMST5550-QX 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 headquartered in Nijmegen, Netherlands, specializing in high-performance, high-reliability discrete and logic devices for automotive, industrial, and consumer markets.

The PMST5550-QX belongs to Nexperia's AEC-Q101-qualified high-voltage bipolar transistor family, engineered specifically for compact, thermally efficient switching and amplification in harsh-environment communication and control systems.

FAQ

Is PMST5550-QX pin-compatible with standard SOT323 NPN transistors?

Yes, PMST5550-QX uses standard SC-70 (SOT323) pinning: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This matches JEDEC MO-203-AB and aligns with industry-standard footprints like those for BC846 series, enabling direct PCB layout reuse where voltage and current ratings permit.

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

At T_amb = 100 °C, derating applies due to R_th(j-a) = 625 K/W and P_tot = 200 mW at 25 °C. Junction temperature must stay ≤150 °C, allowing ~80 mW dissipation at 100 °C ambient. With V_CE(sat) ≈ 200 mV, this supports ~400 mA peak but only ~160 mA continuous I_C under worst-case thermal conditions.

Does PMST5550-QX support pulsed operation beyond its DC ratings?

Yes-datasheet specifies I_CM = 600 mA and IBM = 100 mA for pulsed conditions (t_p ≤ 300 µs, duty cycle δ ≤ 0.02). These values are validated for short-duration switching events such as telephone ring detection pulses or solenoid actuation bursts, provided average power remains within 200 mW limits.

How does the 6 pF collector capacitance affect high-frequency performance?

The C_c = 6 pF at V_CB = 10 V directly limits small-signal bandwidth: with typical load impedances of 1–10 kΩ, f_−3dB ≈ 2.6–26 MHz. This makes PMST5550-QX suitable for audio-band amplification and <10 MHz switching but unsuitable for RF front-end or >50 MHz digital signal routing.