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

onsemi BD138G

Name: BD138G
Brand: onsemi
SKU: BD138G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD138G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: BD138G.pdf

Description:: TRANS PNP 60V 1.5A TO-126

Quantity:: RFQ Add To RFQ list

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Inventory:1,062

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Product details

Overview

BD138G from onsemi is a PNP epitaxial silicon transistor in the BD136 series, rated for −60 V V_CEO, −1.5 A continuous collector current, and 12.5 W collector dissipation at T_C = 25°C; used as a medium-power amplifier or switch in complementary audio output stages with BD137.

For engineers reviewing the BD138G datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO rating, h_FE at 150 mA and 500 mA, V_CE(sat) at I_C = 500 mA / I_B = 50 mA, thermal derating curve, and TO−126 package mechanical compatibility.

Technical Context

This device operates as a linear or switching PNP bipolar junction transistor with fixed emitter-base and collector-base junction structures. Its DC current gain (h_FE) ranges from 63 to 250 depending on collector current level-63 min at I_C = −150 mA, 25 min at I_C = −500 mA-and exhibits V_CE(sat) ≤ −0.5 V under forced β = 10 drive conditions.

Thermal performance is defined by a 12.5 W maximum collector dissipation at case temperature 25°C, derating linearly to zero at 175°C; safe operating area (SOA) is limited by secondary breakdown and thermal constraints, with pulsed IC max up to −3.0 A at 2% duty cycle.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−60 V: Maximum sustained collector-emitter voltage before avalanche breakdown in common-emitter configuration.
I_C (DC)	−1.5 A: Continuous collector current limit defining steady-state power handling capability.
P_C (T_C = 25°C)	12.5 W: Maximum power dissipation at case temperature 25°C; requires heatsinking above ambient.
h_FE @ I_C = −150 mA	63–250: Minimum DC current gain at mid-current bias, critical for base drive sizing in linear amplifiers.
V_CE(sat) @ I_C = −500 mA	≤ −0.5 V: Saturation voltage under forced β = 10, determining conduction loss in switching applications.
T_J max	150°C: Maximum allowable junction temperature; sets thermal design margin for reliability.

Pinout & Package

BD138G is housed in a TO−126 (Case 340AS) plastic package with three leads: Emitter (Pin 1), Collector (Pin 2), Base (Pin 3). The flat side of the package faces the viewer with pins downward; Pin 1 is leftmost when viewed from bottom.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Emitter	Current exit terminal; connected to ground or low-side reference in common-emitter configurations.
Pin 2	Collector	Main current input terminal; tied to load or supply rail; electrically isolated from mounting tab.
Pin 3	Base	Control terminal; requires current-limited drive to achieve specified h_FE and saturation performance.

Key Features

Feature	Design Value
Pb−Free construction	RoHS-compliant lead finish enabling environmentally regulated production without exemption waivers.
Complementary pairing	Designed as direct complement to BD137 NPN transistor for push-pull audio output stages.
High V_CEO rating	−60 V withstand enables use in 48 V rail systems and industrial control outputs without derating.
Controlled h_FE spread	Guaranteed minimum h_FE of 63 at I_C = −150 mA supports predictable base resistor selection.

Applications

Audio Power Amplifier Output Stage	DC Motor Driver Half-Bridge
Use Scenario: Complementary pair with BD137 in Class AB push-pull output stage driving 4–8 Ω speakers. IC Role / Device Role / Timing Role: PNP switching/amplifying element delivering negative half-cycle current to load. Use Value: −60 V V_CEO and 12.5 W P_C support 10–15 W RMS output into 8 Ω with minimal thermal derating.	Use Scenario: High-side switch in H-bridge motor driver controlling bidirectional 24 V DC brushed motors. IC Role / Device Role / Timing Role: PNP high-side switch activated by NPN level-shifting stage. Use Value: −1.5 A I_C and ≤ −0.5 V V_CE(sat) enable <1.5 W conduction loss at full load.
Linear Voltage Regulator Pass Element	Industrial Relay Driver
Use Scenario: Series pass transistor in adjustable 3–24 V linear regulator supplying 1.2 A to analog sensor subsystems. IC Role / Device Role / Timing Role: Current-controlled series regulator element dissipating excess voltage as heat. Use Value: 150°C T_J max and SOA curves allow stable operation with 10–15 K/W heatsink under 15 V dropout.	Use Scenario: Driving 12 V/200 mA electromagnetic relays in PLC I/O modules with optocoupler-isolated control. IC Role / Device Role / Timing Role: Saturated switch interfacing microcontroller GPIO to relay coil. Use Value: Guaranteed h_FE ≥ 63 at I_C = −150 mA ensures reliable turn-on with ≤ 2.5 mA base drive.

Audio Power Amplifier Output Stage

DC Motor Driver Half-Bridge

Use Scenario: Complementary pair with BD137 in Class AB push-pull output stage driving 4–8 Ω speakers.

IC Role / Device Role / Timing Role: PNP switching/amplifying element delivering negative half-cycle current to load.

Use Value: −60 V V_CEO and 12.5 W P_C support 10–15 W RMS output into 8 Ω with minimal thermal derating.

Use Scenario: High-side switch in H-bridge motor driver controlling bidirectional 24 V DC brushed motors.

IC Role / Device Role / Timing Role: PNP high-side switch activated by NPN level-shifting stage.

Use Value: −1.5 A I_C and ≤ −0.5 V V_CE(sat) enable <1.5 W conduction loss at full load.

Linear Voltage Regulator Pass Element

Industrial Relay Driver

Use Scenario: Series pass transistor in adjustable 3–24 V linear regulator supplying 1.2 A to analog sensor subsystems.

IC Role / Device Role / Timing Role: Current-controlled series regulator element dissipating excess voltage as heat.

Use Value: 150°C T_J max and SOA curves allow stable operation with 10–15 K/W heatsink under 15 V dropout.

Use Scenario: Driving 12 V/200 mA electromagnetic relays in PLC I/O modules with optocoupler-isolated control.

IC Role / Device Role / Timing Role: Saturated switch interfacing microcontroller GPIO to relay coil.

Use Value: Guaranteed h_FE ≥ 63 at I_C = −150 mA ensures reliable turn-on with ≤ 2.5 mA base drive.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP medium-power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD13005G	TO−252 package; V_CEO = −60 V; I_C = −1.5 A; h_FE min = 40 @ I_C = −150 mA	Surface-mount footprint; lower h_FE requires higher base drive current	Preferred for automated SMT assembly where thermal pad soldering is feasible
BC558B	TO−92 package; V_CEO = −30 V; I_C = −100 mA; h_FE min = 220 @ I_C = −2 mA	Low-power general-purpose device; insufficient voltage/current rating for BD138G roles	Only suitable for signal-level biasing or pre-driver stages-not a functional replacement

Compared with MJD13005G and BC558B, BD138G offers through-hole TO−126 mounting, guaranteed h_FE ≥ 63 at 150 mA, and validated SOA for 1.5 A continuous operation-making it uniquely suited for legacy audio and industrial control designs requiring robust through-hole power transistors.

Availability

BD138G is available at Aetrix Electronics and suitable for audio amplifier output stages, DC motor drivers, linear voltage regulators, and industrial relay drivers requiring stable component supply across long-lifecycle embedded programs.

Supply support for BD138G 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 is a global semiconductor supplier specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BD136 series-including BD138G-is part of onsemi's legacy discrete power transistor portfolio, designed specifically for cost-sensitive, medium-power linear and switching applications in audio, power supplies, and industrial controls.

FAQ

What is the maximum continuous collector current rating for BD138G?

The BD138G has a maximum continuous collector current (I_C) rating of −1.5 A at case temperature T_C = 25°C. This rating assumes adequate heatsinking; actual usable current decreases with rising case temperature per the 12.5 W power derating curve shown in Figure 5 of the BD136/D datasheet. At T_C = 100°C, the practical I_C limit drops to approximately −0.8 A.

Is BD138G pin-compatible with BD136 or BD140?

Yes, BD138G shares identical TO−126 (Case 340AS) packaging and pinout (Emitter–Collector–Base) with BD136 and BD140. However, electrical ratings differ: BD136 is rated for −45 V V_CEO, BD138G for −60 V, and BD140 for −80 V. Substitution requires verification that the lower-voltage BD136 meets system stress requirements-or that the higher-voltage BD140 does not compromise h_FE or switching speed.

What is the guaranteed minimum h_FE for BD138G at I_C = −150 mA?

The BD138G guarantees a minimum DC current gain (h_FE) of 63 at V_CE = −2 V and I_C = −150 mA, per the "h_FE2" specification in the Electrical Characteristics table. This value applies to both BD13810 and BD13816 variants and is measured under pulse test conditions (PW = 350 µs, duty cycle = 2%).

Does BD138G have Pb−Free construction?

Yes, BD138G is explicitly designated as a Pb−Free device in the official onsemi BD136/D datasheet. It complies with RoHS Directive 2011/65/EU and uses lead-free terminations and molding compound. The "G" suffix in BD138G confirms this environmental compliance per onsemi's ordering nomenclature.

What is the safe operating area (SOA) limitation for BD138G at DC operation?

At DC operation, the BD138G's safe operating area is bounded by its 12.5 W collector dissipation limit at T_C = 25°C and secondary breakdown constraints. As shown in Figure 4, the DC boundary follows the 12.5 W hyperbola (P = V × I) down to ~−1.5 A at −8.3 V, then transitions to the −1.5 A current limit line. Operation beyond this envelope risks thermal runaway or bond-wire failure.

BD138G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Bulk

Product Status:: Active

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 1.5 A

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

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 50mA, 500mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 150mA, 2V

Power - Max:: 1.25 W

Frequency - Transition:: -

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126

BD138G FAQ

1.How can I place an order for BD138G through Aetrix?

Please submit a Request for Quotation (RFQ) for BD138G 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 BD138G reliable?

The price and inventory of BD138G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD138G is usually 5 days.

3.What payment methods are accepted for BD138G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD138G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD138G?

BD138G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD138G 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 BD138G?

For technical support, including BD138G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD138G requirements.

6.How does Aetrix verify that BD138G is sourced from the original manufacturer or authorized distributors?

All BD138G 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 BD138G meets industry standards.

7.What is the process for return or replacement of BD138G?

All BD138G units undergo pre-shipment inspection (PSI). If there is an issue with BD138G, 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 BD138G part is unused and in its original packaging.

Return procedure for BD138G:

1.Submit a request within 90 days.

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

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