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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

Nexperia USA Inc. PMSTA42-QX

Name: PMSTA42-QX
Brand: Nexperia USA Inc.
SKU: PMSTA42-QX
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: PMSTA42-QX

Manufacturer:: Nexperia USA Inc.

Category:: Single Bipolar Transistors

Package:: SC-70, SOT-323

Datasheet:: PMSTA42-QX.pdf

Description:: TRANS NPN 300V 0.1A SOT-323

Quantity:: RFQ Add To RFQ list

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Inventory:3,000

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Product details

Overview

PMSTA42-QX from Nexperia is an AEC-Q101-qualified NPN high-voltage transistor in SOT323 (SC-70) package, rated for 300 V_CEO, 100 mA continuous collector current, and 200 mW power dissipation at T_amb ≤ 25 °C; used as a high-voltage switch in telephony line interface circuits.

For engineers reviewing the PMSTA42-QX datasheet, PMSTA42-QX pinout, PMSTA42-QX application, or PMSTA42-QX equivalent, key selection criteria include V_CEO = 300 V, h_FE ≥ 25 @ I_C = 1 mA, V_CE(sat) ≤ 500 mV @ I_C = 20 mA/I_B = 2 mA, thermal resistance R_th(j-a) = 625 K/W, and automotive qualification per AEC-Q101.

Technical Context

This discrete NPN bipolar junction transistor operates in linear or switching mode with open-base V_CEO = 300 V and V_CBO = 300 V, enabling robust high-voltage isolation in off-state. Its f_T = 50 MHz supports moderate-speed switching up to ~10 MHz with controlled rise/fall times.

The device exhibits low leakage: I_CBO ≤ 100 nA at V_CB = 200 V and I_EBO ≤ 100 nA at V_EB = 6 V, ensuring stable biasing in high-impedance telephony interfaces. Thermal performance is defined for FR4 PCB mounting with single-sided copper and standard footprint.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	300 V - Maximum collector-emitter voltage with base open; defines safe blocking capability in high-voltage telephony line feeds.
I_C (continuous)	100 mA - Continuous DC collector current rating; sets maximum steady-state load drive capacity.
h_FE	25–50 - DC current gain range at V_CE = 10 V, I_C = 1–30 mA; determines required base drive for saturation.
V_CE(sat)	≤500 mV @ I_C/I_B = 20 mA/2 mA - Low saturation voltage minimizes conduction loss and self-heating during on-state operation.
R_th(j-a)	625 K/W - Junction-to-ambient thermal resistance on FR4 PCB; dictates maximum power derating above 25 °C ambient.
f_T	50 MHz - Transition frequency at V_CE = 20 V, I_C = 10 mA; indicates usable bandwidth for small-signal amplification or fast switching.

Pinout & Package

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

Pin/Terminal	Circuit Role	Design Meaning
1	Base (B)	Current-controlled input node; requires external resistor-limited drive to achieve target I_C and ensure saturation.
2	Emitter (E)	Common reference terminal; connected to ground or negative rail in common-emitter configuration.
3	Collector (C)	High-voltage output node; handles up to 300 V potential swing while sourcing up to 100 mA load current.

Key Features

Feature	Design Value
AEC-Q101 qualification	Qualified for automotive-grade reliability including temperature cycling, HTRB, and ESD testing-enables use in under-hood and infotainment power control.
300 V V_CEO rating	Supports direct interface with POTS line voltages (up to −48 V nominal + ringing peaks > 150 V) without external clamping.
Low V_CE(sat)	≤500 mV ensures <10 mW conduction loss at 20 mA, reducing thermal stress in sealed telephony modules.
SOT323 footprint	0.95 mm height and 2.0 mm length enable placement in ultra-thin telecom line cards and automotive sensor signal conditioners.

Applications

Telephony Line Interface

Automotive Door Module Control

Use Scenario: Switching of -48 V DC battery feed and AC ringing signals on analog telephone lines.

IC Role / Device Role / Timing Role: High-voltage NPN switch controlling loop current and polarity reversal in SLIC front-end circuits.

Use Value: 300 V blocking capability eliminates need for series Zener clamps; low V_CE(sat) reduces power loss in always-on line monitoring.

Use Scenario: Driving resistive loads such as window motor relays or mirror heater elements in door control units.

IC Role / Device Role / Timing Role: Discrete high-side or low-side switch interfacing microcontroller GPIO to 12 V/24 V automotive loads.

Use Value: AEC-Q101 qualification ensures long-term reliability across −40 °C to +125 °C ambient; compact SOT323 eases routing in dense door module PCBs.

Industrial Modem Signal Path

Smart Meter Communication Interface

Use Scenario: Isolating and switching RS-232/RS-485 line drivers in industrial modems exposed to surge transients.

IC Role / Device Role / Timing Role: Protection-stage transistor limiting fault current during ESD or lightning-induced surges on communication lines.

Use Value: 300 V V_CBO withstands fast-rising transients; low I_CBO ≤ 100 nA prevents false triggering in high-impedance receive paths.

Use Scenario: Controlling PLC or RF transceiver power sequencing in utility smart meters operating on 230 V AC mains-derived rails.

IC Role / Device Role / Timing Role: Voltage-level translation and load switching between microcontroller I/O and isolated communication subsystems.

Use Value: 100 mA I_C supports driving optocoupler LEDs or low-power RF LDO enables; SOT323 allows co-location with isolation barriers.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
PMSTA92-Q	PNP complement; identical V_CEO = 300 V, same SOT323 package, but opposite polarity and inverted biasing requirements.	Used where high-side switching or complementary push-pull stages are needed instead of low-side NPN control.	Select when circuit topology requires PNP configuration or dual-transistor level-shifting networks.
BC846B,215	Lower V_CEO = 65 V, higher h_FE = 200–450, same SOT323 package; not AEC-Q101 qualified.	Suitable only for low-voltage logic-level switching (<65 V), not telephony or automotive HV line control.	Choose only for non-automotive, non-high-voltage applications where gain and cost outweigh voltage and qualification needs.

Compared with PMSTA92-Q (PNP complement) and BC846B,215 (low-voltage general-purpose), PMSTA42-QX uniquely combines 300 V blocking, 100 mA current, AEC-Q101 qualification, and SOT323 size-making it irreplaceable in automotive telephony and industrial HV signal switching where all four attributes are mandatory.

Availability

PMSTA42-QX is available at Aetrix Electronics and suitable for telephony line interface, automotive door module control, and industrial modem signal path applications requiring stable component supply, automotive-grade reliability, and high-voltage discrete switching capability.

Supply support for PMSTA42-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 focused on essential efficiency, delivering high-performance, reliable discrete, logic, and MOSFET components for automotive, industrial, and consumer markets.

PMSTA42-QX belongs to Nexperia's AEC-Q101-qualified high-voltage bipolar transistor product line, designed specifically for robust switching in telephony infrastructure, automotive body electronics, and industrial communication interfaces.

FAQ

Is PMSTA42-QX pin-compatible with BC846 series transistors?

No. While both use SOT323 packages, PMSTA42-QX has base-emitter-collector pinout (1-B, 2-E, 3-C), whereas BC846B,215 uses emitter-base-collector (1-E, 2-B, 3-C). Physical insertion into the same footprint will reverse polarity and cause circuit failure unless board layout is modified.

What is the maximum allowable pulsed collector current for PMSTA42-QX?

The peak collector current I_CM is rated at 200 mA under pulsed conditions (t_p ≤ 300 µs, duty cycle δ ≤ 0.02). This allows brief overcurrent events such as surge handling or inrush limiting, provided average power remains within 200 mW and junction temperature stays below 150 °C.

Does PMSTA42-QX require a heatsink in typical telephony applications?

No. With R_th(j-a) = 625 K/W and typical telephony switching power dissipation <5 mW (V_CE(sat) × I_C), junction temperature rise is <3.1 °C above ambient. Standard FR4 PCB mounting without heatsinking meets thermal requirements across −40 °C to +85 °C operating range.

Can PMSTA42-QX be used in linear amplifier configurations?

Yes, but with constraints. Its f_T = 50 MHz and h_FE variation across I_C support small-signal amplification up to ~5 MHz. However, V_CEO derating above 25 °C and limited power dissipation restrict use to low-gain, low-output-power stages-not RF or audio power amplification.

PMSTA42-QX Specifications

Product attributes: Attribute value

Manufacturer:: Nexperia USA Inc.

Series:: -

Package/Case:: SC-70, SOT-323

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 300 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 2mA, 20mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 10mA, 10V

Power - Max:: 200 mW

Frequency - Transition:: 50MHz

Operating Temperature:: 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-323

PMSTA42-QX FAQ

1.How can I place an order for PMSTA42-QX through Aetrix?

Please submit a Request for Quotation (RFQ) for PMSTA42-QX on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for PMSTA42-QX reliable?

The price and inventory of PMSTA42-QX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PMSTA42-QX is usually 5 days.

3.What payment methods are accepted for PMSTA42-QX?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PMSTA42-QX transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for PMSTA42-QX?

PMSTA42-QX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your PMSTA42-QX order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for PMSTA42-QX?

For technical support, including PMSTA42-QX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PMSTA42-QX requirements.

6.How does Aetrix verify that PMSTA42-QX is sourced from the original manufacturer or authorized distributors?

All PMSTA42-QX products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that PMSTA42-QX meets industry standards.

7.What is the process for return or replacement of PMSTA42-QX?

All PMSTA42-QX units undergo pre-shipment inspection (PSI). If there is an issue with PMSTA42-QX, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The PMSTA42-QX part is unused and in its original packaging.

Return procedure for PMSTA42-QX:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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