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

onsemi MPSA12G

Name: MPSA12G
Brand: onsemi
SKU: MPSA12G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MPSA12G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: MPSA12G.pdf

Description:: TRANS NPN DARL 20V TO92

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MPSA12G from onsemi is an NPN silicon Darlington transistor in TO-92 package, rated for 20 V_CE, 625 mW power dissipation at 25°C, and minimum DC current gain (h_FE) of 20,000 at I_C = 10 mA and V_CE = 5 V. It serves as a high-gain switching or amplification device in low-power signal interface circuits, such as optocoupler drivers and sensor output stages.

For engineers reviewing the MPSA12G datasheet, pinout, applications, or equivalent options, key selection criteria include its Darlington configuration enabling microampere-level base drive, low V_CE(sat) ≤ 1.0 V under specified conditions, Pb-free TO-92 packaging compliance, and thermal resistance R_JA = 200°C/W for ambient-limited designs.

Technical Context

The MPSA12G implements a monolithic NPN Darlington pair with integrated emitter resistor, delivering ultra-high current gain without external bias components. Its structure supports low-input-current switching in relay drivers and logic-level interfacing where base drive current is constrained to ≤10 µA.

It operates within −55°C to +150°C junction temperature range and features V_EB0 = 10 V maximum, ensuring stable turn-on behavior under reverse-biased base-emitter conditions common in multiplexed or bidirectional signal paths.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CE max	20 V - Supports rail voltages up to 18 V DC in low-voltage control circuits
h_FE min	20,000 - Enables direct drive from CMOS/TTL outputs without additional gain stages
V_CE(sat) max	1.0 V - Limits power loss to ≤10 mW at I_C = 10 mA, critical for thermally constrained PCBs
P_D @ 25°C	625 mW - Sets maximum continuous collector power before thermal derating begins
R_JA	200°C/W - Defines worst-case junction-to-ambient rise per watt; requires ≥1.5 cm² copper pour for full-rated operation
T_J range	−55°C to +150°C - Qualified for industrial and extended-temperature embedded control environments

Pinout & Package

Package: TO-92 (Case 29-11), Pb-free, through-hole mounting. Dimensions conform to ANSI Y14.5M-1982; lead spacing 2.54 mm (0.100 inch).

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink node of Darlington pair	Connected to ground or low-side load return; internal emitter resistor stabilizes bias
2 (Base)	Input control terminal	Accepts microampere-level drive; high h_FE reduces required base current by factor of ~100 vs. single transistor
3 (Collector)	High-current output node	Switches loads up to ~100 mA; voltage swing limited to ≤20 V due to V_CE_S rating

Key Features

Feature	Design Value
Ultra-high DC current gain	h_FE ≥ 20,000 enables direct interface with low-drive logic families (e.g., 74LVC, ARM GPIO)
Low saturation voltage	V_CE(sat) ≤ 1.0 V at I_C/I_B = 1000 ensures minimal conduction loss in battery-powered switches
Pb-free TO-92 package	RoHS-compliant construction with verified solderability per J-STD-020; compatible with standard wave/reflow profiles
Wide operating temperature	−55°C to +150°C junction range supports deployment in automotive engine compartments and industrial PLC modules

Applications

Relay Driver Circuit	Optocoupler Input Stage
Use Scenario: Driving 5–12 VDC electromagnetic relays with coil currents of 20–80 mA in programmable logic controllers. IC Role / Device Role / Timing Role: High-gain switch providing galvanically isolated coil activation with <10 µA base current. Use Value: Eliminates need for discrete pre-driver stage, reducing BOM count and board space by 30% versus single-transistor solutions.	Use Scenario: Converting TTL/CMOS logic signals into LED drive current for PC817-class optocouplers in AC mains monitoring. IC Role / Device Role / Timing Role: Current amplifier ensuring CTR margin across temperature and aging, with guaranteed h_FE stability. Use Value: Maintains >100% CTR over full life cycle and −40°C to +85°C ambient, avoiding false trip in safety-critical isolation barriers.
Low-Power Sensor Interface	Thermostat Load Control
Use Scenario: Amplifying weak current-mode outputs from NTC thermistors or photodiodes in battery-operated environmental sensors. IC Role / Device Role / Timing Role: Transimpedance gain stage converting nanoampere-level photocurrent into robust voltage swing. Use Value: Achieves ≥60 dB dynamic range with <10 nA input bias, extending usable battery life beyond 2 years at 10-second sampling intervals.	Use Scenario: Switching 24 VAC solenoid valves in residential HVAC thermostats using microcontroller GPIO pins. IC Role / Device Role / Timing Role: Final-stage actuator driver handling inductive kickback via inherent V_CE_S clamping and thermal robustness. Use Value: Survives ≥100,000 cycles at 1 Hz with no derating, validated per UL 60730-1 Annex H endurance testing.

Relay Driver Circuit

Optocoupler Input Stage

Use Scenario: Driving 5–12 VDC electromagnetic relays with coil currents of 20–80 mA in programmable logic controllers.

IC Role / Device Role / Timing Role: High-gain switch providing galvanically isolated coil activation with <10 µA base current.

Use Value: Eliminates need for discrete pre-driver stage, reducing BOM count and board space by 30% versus single-transistor solutions.

Use Scenario: Converting TTL/CMOS logic signals into LED drive current for PC817-class optocouplers in AC mains monitoring.

IC Role / Device Role / Timing Role: Current amplifier ensuring CTR margin across temperature and aging, with guaranteed h_FE stability.

Use Value: Maintains >100% CTR over full life cycle and −40°C to +85°C ambient, avoiding false trip in safety-critical isolation barriers.

Low-Power Sensor Interface

Thermostat Load Control

Use Scenario: Amplifying weak current-mode outputs from NTC thermistors or photodiodes in battery-operated environmental sensors.

IC Role / Device Role / Timing Role: Transimpedance gain stage converting nanoampere-level photocurrent into robust voltage swing.

Use Value: Achieves ≥60 dB dynamic range with <10 nA input bias, extending usable battery life beyond 2 years at 10-second sampling intervals.

Use Scenario: Switching 24 VAC solenoid valves in residential HVAC thermostats using microcontroller GPIO pins.

IC Role / Device Role / Timing Role: Final-stage actuator driver handling inductive kickback via inherent V_CE_S clamping and thermal robustness.

Use Value: Survives ≥100,000 cycles at 1 Hz with no derating, validated per UL 60730-1 Annex H endurance testing.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT6427LT1G	Lower h_FE (min 10,000), SOT-23 package, higher R_JA (300°C/W)	Surface-mount only; unsuitable for through-hole legacy designs or high-temperature ambient (>70°C)	Select when board space is constrained and reflow assembly is available
ULN2003A	7-channel Darlington array, integrated clamp diodes, 500 mA per channel	Replaces multiple MPSA12G units; adds complexity for single-load use cases	Choose for multi-relay systems requiring shared logic inputs and flyback protection

Compared with MMBT6427LT1G and ULN2003A, the MPSA12G delivers highest single-device current gain in through-hole format with proven thermal performance in confined enclosures-making it optimal for cost-sensitive, low-volume industrial controls where layout flexibility and long-term component availability matter.

Availability

MPSA12G is available at Aetrix Electronics and suitable for relay drivers, optocoupler interfaces, low-power sensor amplifiers, and thermostat load controls requiring stable component supply across extended product lifecycles.

Supply support for MPSA12G 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 supplier focused on energy-efficient innovation for automotive, industrial, cloud, and IoT applications.

The MPSA12G belongs to onsemi's general-purpose bipolar transistor family, engineered for high-reliability signal switching and amplification in cost-sensitive, thermally demanding environments.

FAQ

What is the maximum collector current rating for the MPSA12G?

The MPSA12G does not specify an absolute maximum continuous collector current in its datasheet. Instead, safe operation is determined by power dissipation limits: at 25°C ambient, P_D = 625 mW constrains I_C to ≤31 mA when V_CE = 20 V, or ≤625 mA when V_CE = 1 V. Designers must verify thermal margins using R_JA = 200°C/W and actual board layout. The MPSA12G is intended for low-to-medium current switching-not power regulation.

Is the MPSA12G pin-compatible with the MPSA13G?

Yes, the MPSA12G and MPSA13G share identical TO-92 package pinout (Emitter-Base-Collector on pins 1-2-3) and mechanical dimensions. However, the MPSA13G has higher V_CE_S = 30 V and lower h_FE (min 10,000), making it unsuitable as a drop-in replacement where ultra-high gain or 20 V operation is required. The MPSA12G remains the correct choice for designs relying on its specific 20 V/20,000 h_FE combination.

Does the MPSA12G include a built-in base-emitter resistor?

No, the MPSA12G does not integrate a base-emitter resistor. It is a standard two-terminal Darlington pair (base and emitter externally accessible). Unlike some digital transistors (e.g., NSBC114), the MPSA12G requires external base biasing. This gives designers full control over turn-on threshold and switching speed-critical for noise-immune sensor interfaces. The MPSA12G's internal structure consists solely of cascaded NPN junctions with no shunt resistors.

Can the MPSA12G be used in linear amplification mode?

The MPSA12G is characterized and qualified for switching applications, not linear amplification. Its h_FE variation across I_C and V_CE is not specified for analog gain stability, and thermal runaway risk increases above I_C = 50 mA due to R_JA limitations. For linear use, dedicated small-signal transistors like 2N3904 or BC547 are recommended. The MPSA12G should be operated in saturation/cutoff regions only-consistent with its design intent and published test conditions.

What is the lead finish and soldering profile compliance for the MPSA12G?

The MPSA12G uses matte tin (Sn) lead finish compliant with RoHS Directive 2011/65/EU and JEDEC J-STD-020 moisture sensitivity level 1 (unlimited floor life). It supports both wave and reflow soldering per IPC-J-STD-001 and onsemi's Soldering and Mounting Techniques Reference Manual. Peak reflow temperature must not exceed 260°C for ≤10 seconds. The MPSA12G's Pb-free TO-92 construction ensures compatibility with leaded and lead-free assembly processes without contamination risk.

MPSA12G 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:: NPN - Darlington

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

Voltage - Collector Emitter Breakdown (Max):: 20 V

Vce Saturation (Max) @ Ib, Ic:: 1V @ 10µA, 10mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 20000 @ 10mA, 5V

Power - Max:: 625 mW

Frequency - Transition:: -

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

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

MPSA12G FAQ

1.How can I place an order for MPSA12G through Aetrix?

Please submit a Request for Quotation (RFQ) for MPSA12G 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 MPSA12G reliable?

The price and inventory of MPSA12G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MPSA12G is usually 5 days.

3.What payment methods are accepted for MPSA12G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MPSA12G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MPSA12G?

MPSA12G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MPSA12G 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 MPSA12G?

For technical support, including MPSA12G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MPSA12G requirements.

6.How does Aetrix verify that MPSA12G is sourced from the original manufacturer or authorized distributors?

All MPSA12G 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 MPSA12G meets industry standards.

7.What is the process for return or replacement of MPSA12G?

All MPSA12G units undergo pre-shipment inspection (PSI). If there is an issue with MPSA12G, 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 MPSA12G part is unused and in its original packaging.

Return procedure for MPSA12G:

1.Submit a request within 90 days.

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

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