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onsemi BC309BTA
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- Part No.:
- BC309BTA
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
BC309BTA.pdf
- Description:
- TRANS PNP 25V 0.1A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:8,016
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Product details
Overview
BC309BTA from Fairchild Semiconductor is a PNP epitaxial silicon transistor optimized for low-noise amplifier and switching applications, with VCEO = −25 V, IC = −100 mA, PC = 500 mW, hFE = 180–460 (Class B), and fT = 130 MHz - used in audio preamplifier stages and relay driver circuits.
For engineers reviewing the BC309BTA datasheet, pinout, applications, or equivalent options, key selection considerations include its low-noise performance (NF = 4 dB at 30–15 kHz), TO-92 package compatibility, VCE(sat) ≤ −0.3 V at IC = −100 mA/IB = −5 mA, and hFE classification band B for predictable gain matching in production designs.
Technical Context
The BC309BTA operates as a general-purpose PNP bipolar junction transistor with epitaxial base construction enabling high fT and stable hFE across temperature. Its low-noise specification (NF = 4 dB) is validated at VCE = −5 V, IC = −0.2 mA, RG = 2 kΩ, and 30–15 kHz bandwidth - distinct from BC307/308 variants.
It features tight hFE grouping (180–460, Class B), low Cob = 6 pF and Cib = 12 pF at specified bias conditions, and guaranteed VBE(on) = −0.55 to −0.7 V - supporting reliable biasing in discrete amplifier topologies and linear switching circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | −25 V - maximum safe collector-emitter voltage before breakdown under open-base condition; defines rail headroom in PNP switch/amplifier designs. |
| IC (DC) | −100 mA - continuous collector current rating; supports medium-current load switching and small-signal amplification without derating at 25°C. |
| hFE (Class B) | 180–460 - DC current gain range at VCE = −5 V, IC = −2 mA; enables predictable bias point setting and gain stability in production batches. |
| fT | 130 MHz - current gain–bandwidth product at VCE = −5 V, IC = −10 mA; confirms suitability for audio-frequency and low-MHz signal amplification. |
| NF | 4 dB - noise figure at VCE = −5 V, IC = −0.2 mA, RG = 2 kΩ, 30–15 kHz; specifies low-noise capability critical for microphone preamp and sensor interface stages. |
| VCE(sat) | −0.3 V @ IC = −100 mA / IB = −5 mA - low saturation voltage ensures minimal power loss and heat generation in saturated-switch operation. |
| Package | TO-92 - through-hole plastic package with standardized 1.27 mm lead pitch; compatible with legacy PCB layouts and manual assembly processes. |
Pinout & Package
BC309BTA uses the standard TO-92 package with 3 leads: Collector (lead 1), Base (lead 2), Emitter (lead 3), as defined in Fairchild's Rev. A2 datasheet. Pin numbering follows the flat-side-up orientation with leads down, left-to-right sequence.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Collector | Main current sink terminal; connects to negative supply rail in PNP common-emitter configurations. |
| 2 | Base | Control input; requires negative bias relative to emitter to turn on; drives switching or sets Q-point in amplifiers. |
| 3 | Emitter | Current source terminal; typically tied to ground or positive rail; provides reference for base-emitter junction control. |
Key Features
| Feature | Design Value |
|---|---|
| Low-noise performance | NF = 4 dB at 30–15 kHz enables use in sensitive analog front-ends where signal integrity is critical. |
| Class B hFE grouping | 180–460 gain range allows consistent DC bias design across units without individual trimming. |
| High fT | 130 MHz bandwidth supports stable amplification up to mid-audio frequencies with margin. |
| Low VCE(sat) | −0.3 V at full rated current minimizes conduction loss and thermal stress in switching applications. |
| TO-92 mechanical compatibility | Standard footprint ensures drop-in replacement for BC307/308/309 family parts in existing through-hole designs. |
Applications
| Audio Preamp Stage | Relay Driver Circuit |
|---|---|
|
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in battery-powered voice recorders. IC Role / Device Role / Timing Role: PNP small-signal amplifier configured in common-emitter topology with emitter degeneration. Use Value: Low NF = 4 dB preserves SNR; hFE consistency ensures repeatable gain calibration across production units. |
Use Scenario: Driving 12 V, 40 mA coil relays from microcontroller GPIO pins in industrial control panels. IC Role / Device Role / Timing Role: Saturated PNP switch with base resistor network providing current gain and isolation. Use Value: VCE(sat) ≤ −0.3 V limits power dissipation to <12 mW; TO-92 thermal resistance supports continuous operation. |
| LED Current Sink | Level-Shifting Interface |
|
Use Scenario: Controlling high-brightness indicator LEDs in automotive dashboards requiring reverse-polarity protection. IC Role / Device Role / Timing Role: Constant-current sink using emitter resistor feedback in grounded-emitter configuration. Use Value: IC = −100 mA rating accommodates multiple parallel LEDs; VCEO = −25 V withstands load dump transients. |
Use Scenario: Translating 3.3 V logic outputs to −5 V or −12 V control signals in mixed-supply test equipment. IC Role / Device Role / Timing Role: Inverting level shifter with pull-up to negative rail and active pull-down via BC309BTA. Use Value: Fast fT = 130 MHz supports clean edge transitions; low Cob = 6 pF minimizes capacitive loading on driving node. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PNP small-signal transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BC327-25 | Same TO-92 package; hFE = 250–630 (Group C); VCEO = −45 V; higher voltage rating but no low-noise spec. | Preferred in higher-voltage switching where noise is secondary; not recommended for audio preamp due to unspecified NF. | Select BC327-25 only when VCEO > −25 V is required and low-noise performance is not needed. |
| MMBT3906LT1G | SOT-23 surface-mount package; hFE = 100–300; VCEO = −40 V; NF = 10 dB (worse than BC309BTA). | Used in space-constrained PCBs; unsuitable for low-noise analog stages due to higher noise and lower fT. | Choose MMBT3906LT1G only for automated SMT assembly where TO-92 is incompatible and noise performance is non-critical. |
Compared with BC327-25 and MMBT3906LT1G, BC309BTA uniquely delivers verified low-noise operation (NF = 4 dB) in a through-hole TO-92 package with Class B hFE consistency - making it irreplaceable in cost-sensitive, noise-sensitive audio and sensor interface designs requiring manual or legacy assembly.
Availability
BC309BTA is available at Aetrix Electronics and suitable for audio preamplifier stages, relay driver circuits, and LED current sink applications requiring stable component supply, long-lifecycle support, and legacy through-hole compatibility.
Supply support for BC309BTA 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
Fairchild Semiconductor was a U.S.-based semiconductor company specializing in analog and discrete power products before its acquisition by ON Semiconductor in 2016.
The BC309BTA belongs to Fairchild's legacy BC307/308/309 PNP transistor family, designed specifically for general-purpose low-noise amplification and medium-current switching in consumer, industrial, and instrumentation systems.
FAQ
What is the hFE range for BC309BTA?
The BC309BTA is classified as Class B, with a guaranteed DC current gain (hFE) range of 180 to 460 at VCE = −5 V and IC = −2 mA. This grouping ensures predictable biasing and gain stability across production lots, distinguishing it from BC309A (120–220) and BC309C (380–800). The hFE value is measured under standardized conditions per Fairchild's Rev. A2 datasheet.
Does BC309BTA have a specified noise figure?
Yes, BC309BTA has a documented noise figure of 4 dB, measured at VCE = −5 V, IC = −0.2 mA, RG = 2 kΩ, and frequency range 30–15 kHz. This low-noise specification is explicitly assigned to the BC309 variant (not BC307 or BC308) and is a key differentiator for audio and sensor signal conditioning applications.
What is the maximum collector-emitter voltage rating for BC309BTA?
The BC309BTA has a maximum collector-emitter voltage (VCEO) rating of −25 V under open-base conditions at Ta = 25°C. This is confirmed in both the Absolute Maximum Ratings and Electrical Characteristics tables of the Fairchild BC307/308/309 datasheet Rev. A2. Exceeding this voltage risks avalanche breakdown and permanent device failure.
Is BC309BTA available in surface-mount packaging?
No, BC309BTA is exclusively offered in the through-hole TO-92 package. Fairchild did not release a surface-mount variant of the BC309BTA; alternatives like MMBT3906LT1G are functionally similar but differ in noise performance, gain range, and package type. BC309BTA's TO-92 footprint is fixed and non-replaceable with SMT equivalents without board redesign.
What is the typical saturation voltage of BC309BTA?
The typical collector-emitter saturation voltage (VCE(sat)) of BC309BTA is −0.3 V when operated at IC = −100 mA and IB = −5 mA. This value is specified in the Electrical Characteristics table and reflects efficient conduction in saturated switching mode, minimizing power loss and self-heating during extended duty cycles.
BC309BTA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Packaging:
- Tape & Box (TB)
- Product Status:
- Obsolete
- Transistor Type:
- PNP
- Current - Collector (Ic) (Max):
- 100 mA
- Voltage - Collector Emitter Breakdown (Max):
- 25 V
- Vce Saturation (Max) @ Ib, Ic:
- 500mV @ 5mA, 100mA
- Current - Collector Cutoff (Max):
- 15nA
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 180 @ 2mA, 5V
- Power - Max:
- 500 mW
- Frequency - Transition:
- 130MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
BC309BTA FAQ
1.How can I place an order for BC309BTA through Aetrix?
Please submit a Request for Quotation (RFQ) for BC309BTA 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 BC309BTA reliable?
The price and inventory of BC309BTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC309BTA is usually 5 days.
3.What payment methods are accepted for BC309BTA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC309BTA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BC309BTA?
BC309BTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BC309BTA 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 BC309BTA?
For technical support, including BC309BTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC309BTA requirements.
6.How does Aetrix verify that BC309BTA is sourced from the original manufacturer or authorized distributors?
All BC309BTA 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 BC309BTA meets industry standards.
7.What is the process for return or replacement of BC309BTA?
All BC309BTA units undergo pre-shipment inspection (PSI). If there is an issue with BC309BTA, 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 BC309BTA part is unused and in its original packaging.
Return procedure for BC309BTA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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