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onsemi KSC945LBU
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- Part No.:
- KSC945LBU
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
KSC945LBU.pdf
- Description:
- TRANS NPN 50V 0.15A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:5,409
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Product details
Overview
KSC945LBU from onsemi is an NPN epitaxial silicon transistor designed for audio-frequency amplification and high-frequency oscillator circuits, with a collector-base voltage rating of 60 V, DC current gain (hFE) of 120–240 at IC = 1.0 mA, and current gain bandwidth product (fT) of 300 MHz typical. It operates in TO-92 package with emitter-collector-base pinout and supports general-purpose linear switching in low-power analog stages.
For engineers reviewing the KSC945LBU datasheet, pinout, applications, or equivalent options, key selection considerations include its 50 V VCEO rating, 250 mW power dissipation, 300 MHz fT, noise figure of 4.0 dB at 1 kHz, and Pb-free TO-92 3-lead mechanical outline (Case 135AN).
Technical Context
This discrete NPN bipolar junction transistor uses epitaxial base construction to achieve high-speed performance and stable DC gain across temperature. Its fT = 300 MHz enables use in VHF oscillator and RF preamplifier roles up to ~100 MHz, while the 50 V VCEO and 150 mA IC rating suit medium-voltage, low-current signal conditioning.
The device exhibits low saturation voltages-VCE(sat) = 0.15–0.30 V at IC = 100 mA/IB = 10 mA-and output capacitance Cob = 2.5 pF at VCB = 6 V, supporting fast switching and minimal Miller effect in tuned amplifier designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCBO | 60 V - Maximum reverse bias voltage between collector and base before breakdown; defines safe operation in common-base configurations. |
| VCEO | 50 V - Maximum collector-emitter voltage under open-base condition; sets upper limit for supply rails in common-emitter amplifiers. |
| IC | 150 mA - Continuous collector current rating; determines maximum signal swing and power handling in linear or switching modes. |
| fT | 300 MHz (typ) - Current gain bandwidth product; indicates usable frequency range for small-signal amplification and oscillator loop stability. |
| hFE | 120–240 - DC current gain at VCE = 6 V, IC = 1.0 mA; defines base drive requirements and bias network sensitivity. |
| PD | 250 mW - Maximum power dissipation at 25°C ambient; requires thermal derating (2.0 mW/°C) above TA = 25°C for PCB layout planning. |
| Cob | 2.5 pF - Output capacitance at VCB = 6 V; impacts high-frequency roll-off and tuning range in LC oscillator tanks. |
Pinout & Package
Package: TO-92 3-lead (Case 135AN), Pb-free, through-hole mounting. Dimensions: 4.825 mm × 4.76 mm body, standard leadform.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Current sink terminal | Reference node for biasing; connects to ground or emitter resistor in common-emitter configuration. |
| 2 (Base) | Control input | Receives forward-biased current to modulate collector current; requires current-limiting resistor in most driver circuits. |
| 3 (Collector) | Current source terminal | Delivers amplified output current; connects to load or next stage; polarity-sensitive in DC-coupled designs. |
Key Features
| Feature | Design Value |
|---|---|
| High fT bandwidth | 300 MHz typical - Enables stable oscillation and broadband amplification up to VHF band without external compensation. |
| Low VCE(sat) | 0.15–0.30 V at IC = 100 mA - Reduces conduction loss and improves efficiency in Class-A amplifier and switch-mode driver applications. |
| Low noise figure | 4.0 dB at 1 kHz - Supports high-fidelity audio preamplification where SNR preservation is critical in microphone or phono stages. |
| Complementary pairing | Matched to KSA733 PNP - Allows implementation of push-pull, differential pair, or complementary symmetry amplifier topologies. |
| TO-92 mechanical standardization | Case 135AN footprint - Ensures compatibility with legacy PCB tooling, wave soldering profiles, and hand-soldering workflows. |
Applications
| Audio Preamp Stage | RF Local Oscillator |
|---|---|
Use Scenario: Low-noise voltage amplification of microphone or line-level signals prior to ADC or tone control. IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration. Use Value: 4.0 dB noise figure and hFE ≥120 ensure clean gain without degrading SNR in battery-powered portable audio devices. | Use Scenario: Fundamental-mode Colpitts or Hartley oscillator generating 30–100 MHz local oscillator signals for AM/FM receivers. IC Role / Device Role / Timing Role: Active gain element sustaining resonance in LC tank circuit with feedback network. Use Value: 300 MHz fT and 2.5 pF Cob enable reliable oscillation with predictable start-up and frequency stability over temperature. |
| DC Motor Driver Switch | Signal Level Shifter |
Use Scenario: Low-side switching of 12 V, <100 mA brushed DC motors in embedded motion control modules. IC Role / Device Role / Timing Role: Saturated NPN switch controlled by microcontroller GPIO. Use Value: VCE(sat) ≤0.30 V minimizes heat generation and extends battery life in intermittent-duty motor actuation. | Use Scenario: Translating 3.3 V logic outputs to 5 V or 12 V interface levels in mixed-voltage digital systems. IC Role / Device Role / Timing Role: Active pull-up transistor in open-collector level translation topology. Use Value: hFE ≥120 ensures full saturation with low base drive current, enabling direct connection to MCU I/O pins without buffer ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar NPN small-signal transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 2N3904 | fT = 300 MHz (same), VCEO = 40 V (lower), hFE = 100–300 (wider spread), Cob = 4.0 pF (higher) | Less suitable for 50 V rail designs; higher Cob limits VHF oscillator Q-factor | Select when lower cost and wider hFE tolerance are acceptable, and VCEO ≤40 V suffices. |
| BC547C | fT = 300 MHz (same), VCEO = 45 V (lower), hFE = 420–800 (higher), Cob = 4.5 pF (higher) | Higher hFE reduces base drive needs but increases sensitivity to thermal drift in bias networks | Prefer for high-gain DC-coupled amplifiers where VCEO margin >5 V is available. |
Compared with 2N3904 and BC547C, the KSC945LBU offers superior VCEO (50 V) and lower Cob (2.5 pF), making it more robust in 48 V telecom interfaces and higher-Q RF oscillator designs-though its discontinued status requires careful BOM lifecycle planning.
Availability
KSC945LBU is available at Aetrix Electronics and suitable for audio preamplifiers, RF oscillator circuits, low-side motor drivers, and logic level shifters requiring stable component supply and legacy TO-92 footprint compatibility.
Supply support for KSC945LBU 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, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The KSC945LBU belongs to onsemi's legacy discrete transistor portfolio, engineered for cost-sensitive, high-volume analog signal conditioning and switching applications where reliability, TO-92 standardization, and proven performance are prioritized over advanced packaging.
FAQ
What is the pin configuration of the KSC945LBU?
The KSC945LBU uses a standard TO-92 3-lead package with pin 1 as emitter, pin 2 as base, and pin 3 as collector-verified per onsemi's marking diagram and mechanical drawings (Case 135AN). This emitter-base-collector order differs from center-collector variants like KSC945CYTA and must be confirmed during PCB layout to avoid functional failure.
Is the KSC945LBU RoHS-compliant and lead-free?
Yes, the KSC945LBU is Pb-free and RoHS-compliant, as explicitly stated in the ordering information section of the official onsemi datasheet (Publication Order Number KSC945/D, Rev. 3, June 2024). It ships in bulk packaging and meets JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for standard reflow processes.
Why is the KSC945LBU marked as discontinued, and what does that mean for new designs?
The KSC945LBU is marked "DISCONTINUED" in the onsemi datasheet, indicating it is not recommended for new designs. While existing inventory remains available, long-term supply cannot be guaranteed. Engineers designing with KSC945LBU should initiate second-source evaluation or migration planning using verified alternatives such as 2N3904 or BC547C.
What is the maximum operating junction temperature for the KSC945LBU?
The KSC945LBU has a maximum junction temperature (TJ) of 150°C, as specified in the Absolute Maximum Ratings table. This allows operation in industrial environments up to +85°C ambient when derated properly-using its 2.0 mW/°C thermal derating factor and 500°C/W RθJA value to calculate safe power limits at elevated temperatures.
Can the KSC945LBU replace the KSC945YTA in an existing design?
Yes, the KSC945LBU can replace KSC945YTA in most cases: both share identical electrical specifications, TO-92 package (Case 135AN), and Pb-free construction. However, KSC945YTA is discontinued and shipped in tape-and-reel (FNFLD), whereas KSC945LBU is supplied in bulk-requiring adjustment in automated assembly feed systems.
KSC945LBU 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):
- 150 mA
- Voltage - Collector Emitter Breakdown (Max):
- 50 V
- Vce Saturation (Max) @ Ib, Ic:
- 300mV @ 10mA, 100mA
- Current - Collector Cutoff (Max):
- 100nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 350 @ 1mA, 6V
- Power - Max:
- 250 mW
- Frequency - Transition:
- 300MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
KSC945LBU FAQ
1.How can I place an order for KSC945LBU through Aetrix?
Please submit a Request for Quotation (RFQ) for KSC945LBU 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 KSC945LBU reliable?
The price and inventory of KSC945LBU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC945LBU is usually 5 days.
3.What payment methods are accepted for KSC945LBU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC945LBU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KSC945LBU?
KSC945LBU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KSC945LBU 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 KSC945LBU?
For technical support, including KSC945LBU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC945LBU requirements.
6.How does Aetrix verify that KSC945LBU is sourced from the original manufacturer or authorized distributors?
All KSC945LBU 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 KSC945LBU meets industry standards.
7.What is the process for return or replacement of KSC945LBU?
All KSC945LBU units undergo pre-shipment inspection (PSI). If there is an issue with KSC945LBU, 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 KSC945LBU part is unused and in its original packaging.
Return procedure for KSC945LBU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
KSC945LBU Tags
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