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onsemi KSC945YBU
- Part No.:
- KSC945YBU
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
KSC945YBU.pdf
- Description:
- TRANS NPN 50V 0.15A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,690
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Product details
Overview
KSC945YBU from onsemi is an NPN epitaxial silicon transistor designed for audio-frequency amplification and high-frequency oscillator circuits, with a 60 V collector-base breakdown voltage (VCBO), 300 MHz current gain bandwidth product (fT), and 250 mW power dissipation in TO-92 package. It operates up to 150 °C junction temperature and delivers DC current gain (hFE) of 120–240 at IC = 1.0 mA.
For engineers reviewing the KSC945YBU datasheet, pinout, applications, or equivalent options, key selection criteria include its fT performance, low VCE(sat) of 0.15 V (typ), noise figure of 4.0 dB at 1 kHz, Cob of 2.5 pF, and compatibility with complementary PNP KSA733 in push-pull or differential pair designs.
Technical Context
This discrete NPN transistor employs epitaxial base construction for high-speed switching and linear amplification. Its fT = 300 MHz (typ) and Cob = 2.5 pF support stable operation in RF oscillator and wideband audio preamp stages up to ~100 MHz.
The device features a fixed lead configuration (Emitter–Base–Collector, pins 1–2–3), specified VCE(sat) ≤ 0.30 V at IC = 100 mA/IB = 10 mA, and guaranteed BVCEO ≥ 50 V - enabling use in low-voltage, medium-current signal paths where thermal derating (2.0 mW/°C above 25 °C) must be applied.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCBO | 60 V - maximum reverse bias between collector and base before breakdown; defines safe operating range in common-base configurations. |
| fT | 300 MHz (typ) - usable small-signal frequency limit for amplifier gain; supports HF oscillator and broadband preamp design. |
| hFE | 120–240 - DC current gain at VCE = 6 V, IC = 1.0 mA; enables predictable biasing in Class-A amplifiers. |
| VCE(sat) | 0.15 V (typ), ≤0.30 V (max) at IC = 100 mA/IB = 10 mA - ensures low conduction loss in switching applications. |
| Cob | 2.5 pF (typ) at VCB = 6 V - limits Miller effect in high-gain stages; critical for stability in tuned RF circuits. |
| PD | 250 mW at TA = 25 °C - sets absolute power handling; requires thermal derating (2.0 mW/°C) above ambient. |
Pinout & Package
Package: TO-92 (Case 135AN), through-hole, Pb-free, 3-pin plastic package with standard leadform (4.825 mm × 4.76 mm footprint).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Current output terminal | Reference node for bias networks; connects to ground or emitter degeneration resistors in CE amplifiers. |
| 2 (Base) | Control input terminal | Receives drive current to modulate collector current; requires current-limiting resistor in most switch/amplifier topologies. |
| 3 (Collector) | Current input terminal | Connects to supply rail or load; handles up to 150 mA continuous; polarity-sensitive in circuit layout. |
Key Features
| Feature | Design Value |
|---|---|
| High fT performance | 300 MHz typical - enables reliable operation in VHF oscillator and broadband audio driver stages. |
| Low saturation voltage | VCE(sat) ≤ 0.30 V - reduces power loss and self-heating during switching, improving efficiency in pulse amplifiers. |
| Complementary pairing | Matched as NPN counterpart to KSA733 PNP - simplifies design of push-pull output stages and differential amplifiers. |
| Low noise figure | NF = 4.0 dB at 1 kHz - supports high-fidelity preamplifier use where signal integrity in audio band is critical. |
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 = 120–240 ensure clean gain without introducing audible hiss or distortion. | Use Scenario: Generating stable 10–50 MHz local oscillator signal in AM/FM receiver front-ends. IC Role / Device Role / Timing Role: Active device in Colpitts or Hartley oscillator topology. Use Value: 300 MHz fT and 2.5 pF Cob allow sustained oscillation with minimal phase noise and tuning sensitivity. |
| DC Motor Driver Switch | Differential Pair Amplifier |
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 switch controlling motor current path to ground. Use Value: VCE(sat) ≤ 0.30 V minimizes I²R losses and heat generation during continuous PWM operation. | Use Scenario: Input stage of instrumentation amplifier or analog sensor interface requiring matched gain and offset. IC Role / Device Role / Timing Role: One leg of NPN-PNP complementary differential pair with KSA733. Use Value: Complementary pairing enables balanced common-mode rejection and symmetrical slew response. |
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 typ), but lower VCBO = 60 V (same), higher VCEO = 40 V vs. KSC945YBU's 50 V; hFE min = 100 vs. 120. | Widely available, standardized footprint; less optimized for HF oscillator due to higher Cob (~4 pF). | Select when legacy compatibility or broad distributor stock is prioritized over lowest noise or highest fT margin. |
| BC547B | fT = 300 MHz (same typ), VCBO = 50 V (lower than 60 V); hFE = 200–450 (wider spread); Cob ≈ 4.5 pF. | Better hFE consistency but reduced voltage headroom and higher capacitance limit HF stability. | Prefer for general-purpose amplification where 50 V VCBO suffices and tighter hFE binning is needed. |
Compared with 2N3904 and BC547B, the KSC945YBU offers superior VCEO rating (50 V), lower Cob (2.5 pF), and guaranteed hFE minimum of 120 - making it more suitable for noise-sensitive HF oscillator and audio preamp designs where voltage margin and capacitance control are critical.
Availability
KSC945YBU is available at Aetrix Electronics and suitable for audio preamplifiers, RF oscillator circuits, and low-power DC motor drivers requiring stable component supply and long-term industrial availability despite discontinued status for new designs.
Supply support for KSC945YBU 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 specializing in energy-efficient power, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The KSC945YBU belongs to onsemi's legacy discrete transistor portfolio, engineered for cost-effective, high-reliability signal amplification and switching in space-constrained through-hole applications.
FAQ
What is the pin configuration of the KSC945YBU?
The KSC945YBU uses a fixed TO-92 pinout: Pin 1 is Emitter, Pin 2 is Base, and Pin 3 is Collector. This configuration is confirmed in the official onsemi datasheet (Publication Order Number KSC945/D, Rev. 3, June 2024) and applies to all variants including KSC945YBU. The device is not center-collector - the "-C" suffix denotes that variant, which KSC945YBU does not carry.
Is the KSC945YBU RoHS-compliant and lead-free?
Yes, the KSC945YBU is Pb-free and RoHS-compliant, as explicitly stated in the ordering information section of the onsemi datasheet: "TO−92 3 (Pb−Free)" and "KSC945YBU TO−92 3 (Pb−Free)". It meets JEDEC J-STD-609 Category 1 marking requirements for lead-free terminations.
What is the maximum operating junction temperature for the KSC945YBU?
The KSC945YBU has a maximum junction temperature (TJ) of 150 °C, as specified in the Absolute Maximum Ratings table of the onsemi datasheet. Derating begins above 25 °C ambient at 2.0 mW/°C, meaning usable power dissipation drops to 150 mW at 100 °C ambient.
Can the KSC945YBU replace the KSC945CYTA in existing designs?
Yes, the KSC945YBU is functionally identical to KSC945CYTA in electrical and thermal specifications, differing only in packaging (bulk vs. tape-and-reel) and discontinuation status. Both share identical TO-92 3 (Case 135AN) package, pinout, and full parametric performance per the same datasheet revision.
Why is the KSC945YBU marked as discontinued, and is it still supported?
The KSC945YBU is marked "DISCONTINUED" per onsemi's note indicating it is "not recommended for new design." However, it remains available through authorized channels like Aetrix Electronics with full traceable sourcing and lifecycle coordination support for legacy system maintenance and production continuity.
KSC945YBU 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:
- 120 @ 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
KSC945YBU FAQ
1.How can I place an order for KSC945YBU through Aetrix?
Please submit a Request for Quotation (RFQ) for KSC945YBU 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 KSC945YBU reliable?
The price and inventory of KSC945YBU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC945YBU is usually 5 days.
3.What payment methods are accepted for KSC945YBU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC945YBU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KSC945YBU?
KSC945YBU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KSC945YBU 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 KSC945YBU?
For technical support, including KSC945YBU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC945YBU requirements.
6.How does Aetrix verify that KSC945YBU is sourced from the original manufacturer or authorized distributors?
All KSC945YBU 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 KSC945YBU meets industry standards.
7.What is the process for return or replacement of KSC945YBU?
All KSC945YBU units undergo pre-shipment inspection (PSI). If there is an issue with KSC945YBU, 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 KSC945YBU part is unused and in its original packaging.
Return procedure for KSC945YBU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
KSC945YBU Tags
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MMBT3906LT1G
onsemi
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Diodes Incorporated
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MMBT3904LT1G
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MMBT3906-7-F
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MMBT2222A-7-F
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BC846BLT1G
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BC847B,215
Nexperia USA Inc.
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SMMBT3904LT1G
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MMBTA06LT1G
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