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onsemi BC338
- Part No.:
- BC338
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
BC338.pdf
- Description:
- TRANS NPN 25V 0.8A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:9,702
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Product details
Overview
BC338 from ON Semiconductor is an NPN epitaxial silicon transistor in TO-92 package, rated for 30 V VCEO, 800 mA IC, 625 mW PD, with hFE range 160–400 at 100 mA, and fT = 100 MHz - used in AF driver stages, low-power output amplification, and switching circuits.
For engineers reviewing the BC338 datasheet, pinout, applications, or equivalent options, key selection criteria include its 25 V VCEO rating, 500 mA saturation capability at 50 mA base drive, TO-92 mechanical compatibility, complementary pairing with BC328, and suitability for discrete audio gain blocks and relay drivers.
Technical Context
The BC338 operates as a general-purpose bipolar junction transistor with fixed-emitter configuration, optimized for linear amplification up to ~100 MHz and saturated switching with VCE(sat) ≤ 0.7 V at IC = 500 mA / IB = 50 mA. Its hFE classification (25) specifies DC current gain between 160 and 400 under VCE = 1 V, IC = 100 mA conditions.
Thermal performance is defined by RθJA = 200 °C/W on standard FR-4 PCB (76 mm × 114 mm), enabling operation up to 150 °C junction temperature. It shares pinout and footprint with BC337 but differs in breakdown voltage (25 V vs. 45 V) and gain band.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 25 V - maximum safe collector-emitter voltage before breakdown in common-emitter configuration |
| IC (DC) | 800 mA - continuous collector current handling capacity without thermal runaway on standard PCB |
| PD | 625 mW - maximum power dissipation at 25 °C ambient; derates 5 mW/°C above that temperature |
| hFE (100 mA) | 160–400 - guaranteed DC current gain range for biasing stable Class-A amplifier stages |
| fT | 100 MHz - unity-gain frequency confirming usable bandwidth for AF and low-RF signal amplification |
| VBE(on) | 1.2 V - forward base-emitter voltage required to achieve 300 mA collector current, critical for base resistor sizing |
| Cob | 12 pF - output capacitance at 10 V reverse bias, influencing high-frequency stage stability and bandwidth roll-off |
Pinout & Package
BC338 is housed in a JEDEC TO-92 3-lead plastic package with straight or bent leads, standardized for through-hole mounting. Lead assignment is fixed: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Collector | Main current sink terminal; connects to load or supply rail in common-emitter switch/amplifier configurations |
| 2 | Base | Control input; requires current-limited drive (e.g., via series resistor) to bias transistor into active or saturation region |
| 3 | Emitter | Current source terminal; typically tied to ground or emitter resistor for bias stabilization in amplifier designs |
Key Features
| Feature | Design Value |
|---|---|
| Complementary pair with BC328 | Enables direct replacement in push-pull amplifier stages without circuit redesign or bias recalculations |
| AF-driver stage optimization | Guaranteed hFE ≥ 160 at 100 mA supports stable voltage gain in audio preamplifier and driver circuits |
| Low VCE(sat) | ≤ 0.7 V at 500 mA/50 mA ensures <10% voltage drop across transistor in saturated switching applications |
| TO-92 mechanical standardization | Enables drop-in replacement across legacy designs using BC108, BC547, or other TO-92 NPN transistors |
| 150 °C max junction temperature | Supports reliable operation in enclosed industrial enclosures or near heat-generating components |
Applications
| Audio Frequency Amplifier | Relay Driver Circuit |
|---|---|
|
Use Scenario: Low-voltage audio preamplifier stage driving 10 kΩ load in portable intercom system. IC Role / Device Role / Timing Role: Discrete NPN gain element configured in common-emitter topology with emitter degeneration. Use Value: hFE of 250–400 ensures consistent voltage gain >100 without thermal drift; 100 MHz fT preserves full 20 Hz–20 kHz fidelity. |
Use Scenario: Microcontroller GPIO drives 12 V, 40 mA coil relay in HVAC control panel. IC Role / Device Role / Timing Role: Saturated switch interfacing logic-level signal to inductive load with flyback protection. Use Value: VCE(sat) ≤ 0.7 V minimizes power loss (<28 mW); 800 mA IC rating provides 20× safety margin over relay coil current. |
| Low-Power Output Stage | Signal Level Shifter |
|
Use Scenario: Final output buffer in battery-powered sensor transmitter delivering ±1 V swing into 1 kΩ. IC Role / Device Role / Timing Role: Emitter-follower configured for low-output-impedance buffering with minimal distortion. Use Value: 625 mW PD and 200 °C/W thermal resistance allow sustained 100 mA output without heatsink in ambient ≤ 50 °C. |
Use Scenario: Converting 3.3 V logic signal to 5 V level for legacy microcontroller input. IC Role / Device Role / Timing Role: Common-emitter inverter with pull-up resistor, providing inverted 5 V-compatible output. Use Value: 25 V VCEO safely accommodates 5 V rail; 100–400 hFE ensures fast edge transition and noise immunity at 1 MHz toggle rates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar NPN general-purpose transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BC337-25 | VCEO = 45 V (vs. BC338's 25 V); identical hFE range, package, and pinout | Preferred where higher supply rail or transient margin is needed (e.g., 30 V systems) | Select BC337-25 only if VCE stress exceeds 25 V; otherwise BC338 offers tighter gain consistency at lower voltage |
| BC547B | hFE = 200–450 at 2 mA; lower IC rating (100 mA), smaller fT (300 MHz but tested at lower current) | Better suited for low-current signal switching or RF coupling, not power output stages | Use BC547B only for sub-50 mA loads; BC338 remains preferred for ≥200 mA driver or amplifier roles |
Compared with BC337-25 and BC547B, the BC338 delivers optimal balance of voltage margin, current drive, and gain stability for 12–24 V discrete amplifier and switching applications - especially where 25 V VCEO suffices and ≥500 mA collector current is required.
Availability
BC338 is available at Aetrix Electronics and suitable for audio driver stages, relay interface circuits, low-power output amplifiers, and discrete level-shifting applications requiring stable component supply and long-term obsolescence management.
Supply support for BC338 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
ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensors, and logic devices for automotive, industrial, and consumer markets.
The BC338 belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, designed for cost-sensitive, high-reliability discrete amplification and switching in commercial-grade equipment.
FAQ
What is the maximum collector-emitter voltage rating for BC338?
The BC338 has a maximum collector-emitter voltage (VCEO) rating of 25 V under standard test conditions (IC = 10 mA, IB = 0). This value is strictly limited by its internal epitaxial structure and must not be exceeded to avoid avalanche breakdown. The BC338 datasheet confirms this rating applies specifically to the BC338 variant, distinguishing it from the BC337's 45 V rating.
Is BC338 pin-compatible with BC337?
Yes, BC338 is fully pin-compatible with BC337 - both use identical TO-92 package with Collector/Base/Emitter assigned to pins 1/2/3 respectively. However, BC338 and BC337 differ in absolute maximum ratings (VCEO, VCES) and hFE classification bands, so direct substitution requires verification of voltage stress and gain requirements in the target circuit.
What is the hFE range for BC338 at 100 mA collector current?
The BC338-25 variant guarantees a DC current gain (hFE) range of 160 to 400 when measured at VCE = 1 V and IC = 100 mA. This classification is explicitly defined in the Fairchild/ON Semiconductor BC337/BC338 datasheet Rev. 1.5 and applies only to parts marked "BC33825" - not to BC338-16 or BC338-40 variants.
Can BC338 be used in switching applications?
Yes, BC338 is qualified for switching use with verified VCE(sat) ≤ 0.7 V at IC = 500 mA and IB = 50 mA. Its 800 mA IC rating and 625 mW power dissipation support robust on/off control of relays, LEDs, and small solenoids in 12–24 V systems without external heatsinking under typical ambient conditions.
What is the thermal resistance junction-to-ambient for BC338?
The BC338 has a specified thermal resistance (RθJA) of 200 °C/W when mounted on a standard FR-4 PCB (76 mm × 114 mm, 1.57 mm thick) with minimum land pattern. This value enables calculation of junction temperature rise under real operating power dissipation and informs layout decisions for thermal reliability in sealed enclosures.
BC338 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 800 mA
- Voltage - Collector Emitter Breakdown (Max):
- 25 V
- Vce Saturation (Max) @ Ib, Ic:
- 700mV @ 50mA, 500mA
- Current - Collector Cutoff (Max):
- 100nA
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 100 @ 100mA, 1V
- Power - Max:
- 625 mW
- Frequency - Transition:
- 100MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
BC338 FAQ
1.How can I place an order for BC338 through Aetrix?
Please submit a Request for Quotation (RFQ) for BC338 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 BC338 reliable?
The price and inventory of BC338 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC338 is usually 5 days.
3.What payment methods are accepted for BC338?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC338 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BC338?
BC338 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BC338 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 BC338?
For technical support, including BC338 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC338 requirements.
6.How does Aetrix verify that BC338 is sourced from the original manufacturer or authorized distributors?
All BC338 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 BC338 meets industry standards.
7.What is the process for return or replacement of BC338?
All BC338 units undergo pre-shipment inspection (PSI). If there is an issue with BC338, 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 BC338 part is unused and in its original packaging.
Return procedure for BC338:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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