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

onsemi MPSA55

Name: MPSA55
Brand: onsemi
SKU: MPSA55
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MPSA55

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body

Datasheet:: MPSA55.pdf

Description:: TRANS PNP 60V 0.5A TO92

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MPSA55 from onsemi is a general-purpose PNP bipolar junction transistor (BJT) designed for linear amplification and switching applications in low-power analog and digital circuits. It features a 60 V collector-emitter breakdown voltage (V_CEO), 500 mA continuous collector current (I_C), and 625 mW power dissipation at T_A = 25°C, commonly used in audio preamplifier stages, discrete logic inverters, and relay driver circuits.

For engineers reviewing the MPSA55 datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, TO-92 package compatibility, safe operating area (SOA) limits per Figure 9, DC current gain (h_FE ≥ 100 at I_C = 10 mA), and saturation voltage (V_CE(sat) ≤ 0.25 V at I_C/I_B = 10).

Technical Context

The MPSA55 operates as a medium-speed, low-voltage PNP BJT with f_T = 50 MHz at I_C = 100 mA, V_CE = −1.0 V, and f = 100 MHz. Its base-emitter on voltage is ≤ 1.2 V at I_C = 100 mA, and it exhibits a thermal resistance of R_JA = 200°C/W when mounted on a standard PCB.

It shares the TO-92 (Case 29-11, Style 1) package with pin 1 = Emitter, pin 2 = Base, pin 3 = Collector - identical to MPSA56 but rated for lower V_CEO (60 V vs. 80 V). The device is specified across −55°C to +150°C junction temperature range and supports Pb-free packaging variants (e.g., MPSA55G).

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 V - Maximum allowable collector-to-emitter voltage before breakdown; defines upper rail limit in PNP switch or amplifier stage.
I_C (continuous)	500 mA - Continuous collector current handling capacity; suitable for driving small relays or LED arrays without heatsinking.
P_D @ T_A = 25°C	625 mW - Power dissipation limit at ambient temperature; derates by 5.0 mW/°C above 25°C.
h_FE	≥100 - DC current gain at I_C = 10 mA, V_CE = −1.0 V; ensures reliable base drive sizing in switching designs.
V_CE(sat)	≤0.25 V - Saturation voltage at I_C = 100 mA, I_B = 10 mA; minimizes conduction loss in saturated-switch operation.
f_T	50 MHz - Transition frequency at I_C = 100 mA; supports audio-frequency amplification and moderate-speed digital switching.

Pinout & Package

Package: TO-92 (Case 29-11, Style 1), epoxy-molded plastic with 3 leads. Standard through-hole mounting; lead spacing matches JEDEC TO-92 footprint.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current exit terminal for PNP device; connects to most positive supply rail in common-emitter configurations.
2	Base	Control terminal; requires negative bias relative to emitter to turn on; typical I_B ≈ I_C/h_FE.
3	Collector	Current entry terminal; connects to load and return path; reverse-polarity voltage rating applies (V_CBO = 60 V).

Key Features

Feature	Design Value
PNP polarity with 60 V V_CEO	Enables high-side switching and complementary use with NPN counterparts like MPSA05 in push-pull stages.
h_FE ≥ 100 at low I_C	Reduces required base drive current and simplifies bias network design in linear amplifiers.
V_CE(sat) ≤ 0.25 V	Lowers power loss and self-heating during saturation, improving efficiency in discrete logic and interface drivers.
TO-92 package with Pb-free options	Supports legacy through-hole assembly and RoHS-compliant manufacturing without redesign.

Applications

Audio Preamp Stage	Discrete Logic Inverter
Use Scenario: Low-noise voltage amplification in microphone or sensor signal conditioning front-ends. IC Role / Device Role / Timing Role: PNP BJT configured in common-emitter topology to provide inverted, gain-stable amplification. Use Value: h_FE ≥ 100 and f_T = 50 MHz ensure adequate bandwidth and gain margin up to 20 kHz with minimal distortion.	Use Scenario: Level-shifting and inversion in TTL-compatible discrete gate implementations. IC Role / Device Role / Timing Role: Saturated PNP switch acting as active-low inverter with pull-up resistor. Use Value: V_CE(sat) ≤ 0.25 V guarantees clean logic LOW output (< 0.4 V) under 5 mA load, meeting TTL input thresholds.
Relay Driver Circuit	LED Current Sink
Use Scenario: Driving 12 V, 40 mA coil relays from microcontroller GPIO pins. IC Role / Device Role / Timing Role: High-side PNP switch controlling relay coil between V_CC and ground. Use Value: 500 mA I_C rating and 60 V V_CEO accommodate back-EMF suppression and transient overvoltage.	Use Scenario: Constant-current sinking for indicator LEDs in industrial control panels. IC Role / Device Role / Timing Role: Linear-mode PNP current source with emitter resistor feedback. Use Value: Stable h_FE and low V_BE(on) (≤1.2 V) enable precise 10–20 mA LED current regulation across temperature.

Audio Preamp Stage

Discrete Logic Inverter

Use Scenario: Low-noise voltage amplification in microphone or sensor signal conditioning front-ends.

IC Role / Device Role / Timing Role: PNP BJT configured in common-emitter topology to provide inverted, gain-stable amplification.

Use Value: h_FE ≥ 100 and f_T = 50 MHz ensure adequate bandwidth and gain margin up to 20 kHz with minimal distortion.

Use Scenario: Level-shifting and inversion in TTL-compatible discrete gate implementations.

IC Role / Device Role / Timing Role: Saturated PNP switch acting as active-low inverter with pull-up resistor.

Use Value: V_CE(sat) ≤ 0.25 V guarantees clean logic LOW output (< 0.4 V) under 5 mA load, meeting TTL input thresholds.

Relay Driver Circuit

LED Current Sink

Use Scenario: Driving 12 V, 40 mA coil relays from microcontroller GPIO pins.

IC Role / Device Role / Timing Role: High-side PNP switch controlling relay coil between V_CC and ground.

Use Value: 500 mA I_C rating and 60 V V_CEO accommodate back-EMF suppression and transient overvoltage.

Use Scenario: Constant-current sinking for indicator LEDs in industrial control panels.

IC Role / Device Role / Timing Role: Linear-mode PNP current source with emitter resistor feedback.

Use Value: Stable h_FE and low V_BE(on) (≤1.2 V) enable precise 10–20 mA LED current regulation across temperature.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MPSA56	Higher V_CEO (80 V) and same TO-92 package; otherwise identical pinout and gain specs.	Suitable where higher voltage transients or 24 V system rails require extra margin.	Select MPSA56 if V_CE stress exceeds 60 V; no layout change needed.
BC557	Same PNP polarity, TO-92 package, but lower I_C (100 mA) and V_CEO (45 V); h_FE min = 110.	Restricted to sub-50 mA loads and ≤ 30 V rails; not interchangeable in relay or high-current LED roles.	Use BC557 only in low-power signal-level applications where MPSA55's headroom is unnecessary.

Compared with MPSA55, MPSA56 offers extended voltage safety margin without altering board layout or biasing, while BC557 trades current/voltage capability for slightly higher gain in space-constrained low-power designs.

Availability

MPSA55 is available at Aetrix Electronics and suitable for audio preamplifiers, discrete logic inverters, and relay driver circuits requiring stable component supply, long-term obsolescence management, and RoHS-compliant sourcing.

Supply support for MPSA55 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

onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MPSAxx series is part of onsemi's legacy general-purpose transistor portfolio, engineered for reliability, wide temperature operation, and drop-in compatibility across decades of industrial and commercial designs.

FAQ

What is the maximum collector-emitter voltage rating for MPSA55?

The MPSA55 has a maximum collector-emitter voltage (V_CEO) rating of 60 Vdc. This value is measured with I_C = 1.0 mA and I_B = 0, and defines the absolute upper limit for safe operation in PNP common-emitter configurations. Exceeding this voltage risks avalanche breakdown and permanent device damage. The MPSA55 datasheet confirms this rating in both the Maximum Ratings and Electrical Characteristics tables.

Is MPSA55 a PNP or NPN transistor?

MPSA55 is a PNP bipolar junction transistor, as explicitly stated in the datasheet header ("(PNP) MPSA55, MPSA56*") and confirmed by its pinout (pin 1 = Emitter, pin 2 = Base, pin 3 = Collector) and negative voltage/current conventions throughout the electrical specifications. Its complementary NPN counterpart is the MPSA05, enabling matched pair usage in differential or push-pull circuits.

What package type does MPSA55 use?

MPSA55 uses the TO-92 package (Case 29-11, Style 1), a standard through-hole plastic package with three leads. The datasheet specifies this in the Ordering Information table and Package Dimensions section, confirming pin 1 = Emitter, pin 2 = Base, pin 3 = Collector orientation. Pb-free variants (e.g., MPSA55G) maintain identical mechanical dimensions and soldering profiles.

What is the DC current gain (h_FE) of MPSA55 at typical operating conditions?

The MPSA55 has a minimum DC current gain (h_FE) of 100 when tested at I_C = 10 mA and V_CE = −1.0 Vdc, per the Electrical Characteristics table. This gain remains stable across the −55°C to +150°C junction temperature range, supporting consistent biasing in industrial environments. Gain drops at higher currents but stays usable up to 500 mA.

Can MPSA55 be used as a direct replacement for MPSA56?

MPSA55 is not a direct replacement for MPSA56 due to its lower 60 V V_CEO rating versus MPSA56's 80 V rating - though both share identical pinout, package, and gain characteristics. Substituting MPSA55 in a circuit designed for MPSA56 may cause premature failure under voltage transients >60 V. Use MPSA55 only where verified operating V_CE remains within its 60 V limit.

MPSA55 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 250mV @ 10mA, 100mA

Current - Collector Cutoff (Max):: 100nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 100mA, 1V

Power - Max:: 625 mW

Frequency - Transition:: 50MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92 (TO-226)

MPSA55 FAQ

1.How can I place an order for MPSA55 through Aetrix?

Please submit a Request for Quotation (RFQ) for MPSA55 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 MPSA55 reliable?

The price and inventory of MPSA55 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MPSA55 is usually 5 days.

3.What payment methods are accepted for MPSA55?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MPSA55 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MPSA55?

MPSA55 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MPSA55 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 MPSA55?

For technical support, including MPSA55 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MPSA55 requirements.

6.How does Aetrix verify that MPSA55 is sourced from the original manufacturer or authorized distributors?

All MPSA55 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 MPSA55 meets industry standards.

7.What is the process for return or replacement of MPSA55?

All MPSA55 units undergo pre-shipment inspection (PSI). If there is an issue with MPSA55, 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 MPSA55 part is unused and in its original packaging.

Return procedure for MPSA55:

1.Submit a request within 90 days.

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

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