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onsemi KSC945OBU
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- Part No.:
- KSC945OBU
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
KSC945OBU.pdf
- Description:
- TRANS NPN 50V 0.15A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:8,267
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Product details
Overview
KSC945OBU from onsemi is an NPN epitaxial silicon transistor designed for audio-frequency amplification and high-frequency oscillator circuits, featuring VCBO = 60 V, VCEO = 50 V, IC = 150 mA, fT = 300 MHz (typ), and hFE = 120–240 at IC = 1.0 mA - deployed in compact consumer audio preamps and RF signal generators.
For engineers reviewing the KSC945OBU datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92 package, complementary pairing with KSA733, low VCE(sat) of 0.15 V (typ), noise figure of 4.0 dB at 1 kHz, and Pb-free bulk packaging for legacy design continuity.
Technical Context
This discrete NPN transistor operates as a general-purpose RF/audio amplifier with junction temperature rated to 150°C and thermal resistance RθJA = 500°C/W on standard FR-4 PCBs. Its fT = 300 MHz enables stable gain up to VHF band, while Cob = 2.5 pF supports tuned circuit integration.
The device exhibits DC current gain hFE spanning 120–240 under VCE = 6 V/IC = 1.0 mA, and saturation performance defined by VCE(sat) ≤ 0.30 V at IC = 100 mA/IB = 10 mA - confirming suitability for switching and linear amplification modes in low-power analog stages.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCBO | 60 V - maximum reverse bias voltage between collector and base before breakdown |
| VCEO | 50 V - maximum collector-emitter voltage with base open, defining safe operating range |
| fT | 300 MHz (typ) - usable small-signal bandwidth limit for amplifier or oscillator design |
| hFE | 120–240 - DC current gain range enabling predictable biasing in common-emitter configurations |
| VCE(sat) | 0.15–0.30 V - low saturation voltage supporting efficient switching in low-voltage logic interfaces |
| Cob | 2.5 pF (typ) - output capacitance affecting high-frequency stability and tank circuit tuning |
| PD | 250 mW - maximum power dissipation at 25°C ambient, derating 2.0 mW/°C above |
Pinout & Package
Package: TO-92 (Case 135AN), 3-lead through-hole plastic package with leadform per JEDEC TO-92 outline (4.83 mm × 4.76 mm).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Current sink terminal | Reference node for bias network; connects to ground or emitter resistor in CE amplifier |
| 2 (Base) | Control input | Receives drive current to modulate collector current; requires current-limiting resistor |
| 3 (Collector) | Current source terminal | Delivers amplified output current; connects to load or next stage via coupling capacitor |
Key Features
| Feature | Design Value |
|---|---|
| High fT bandwidth | 300 MHz typical - enables use in VHF oscillators and wideband audio preamplifiers |
| Low noise figure | 4.0 dB at 1 kHz - preserves SNR in sensitive microphone and phono-stage applications |
| Complementary pairing | Matched with KSA733 PNP - supports push-pull Class A/B output stages |
| Pb-free construction | RoHS-compliant TO-92 package - meets environmental compliance for legacy production |
| Stable hFE range | 120–240 at 1 mA - simplifies bias design without requiring individual transistor binning |
Applications
| Audio Preamp Stage | RF Local Oscillator |
|---|---|
Use Scenario: Low-noise voltage amplification in portable cassette players and analog synthesizer voice circuits. 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 300 MHz fT ensure clean gain up to 20 kHz with margin for harmonic content. | Use Scenario: Colpitts or Hartley oscillator core in UHF remote control transmitters (300–400 MHz). IC Role / Device Role / Timing Role: Active gain element sustaining oscillation in LC-tuned feedback loop. Use Value: 300 MHz fT and 2.5 pF Cob enable stable oscillation with minimal external component count. |
| DC Motor Driver Switch | Signal Level Shifter |
Use Scenario: Low-side switching of 12 V/100 mA brushed DC motors in battery-powered toys and actuators. IC Role / Device Role / Timing Role: Saturated switch controlling motor current path to ground. Use Value: VCE(sat) ≤ 0.30 V minimizes conduction loss and self-heating during continuous duty. | Use Scenario: Translating 3.3 V logic signals to 5 V TTL-compatible levels in mixed-voltage microcontroller interfaces. IC Role / Device Role / Timing Role: Common-emitter level translator with fixed bias and pull-up resistor. Use Value: hFE ≥ 120 ensures full saturation with microcontroller GPIO drive capability (≤ 5 mA). |
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 VCEO = 40 V (vs. 50 V); hFE min = 100 (vs. 120) | Marginally lower breakdown rating limits use in 48 V telecom line interfaces | Acceptable where VCEO < 40 V suffices and cost sensitivity outweighs 20 V headroom |
| BC547B | fT = 300 MHz (same typ), VCEO = 45 V, hFE = 200–450 - wider gain spread increases bias variability | Higher hFE spread complicates production calibration in precision gain stages | Preferred when higher gain is needed but requires tighter hFE binning or feedback compensation |
Compared with KSC945OBU, 2N3904 offers identical fT but reduced voltage margin, while BC547B delivers higher gain at the cost of consistency - KSC945OBU balances VCEO headroom, hFE predictability, and legacy TO-92 compatibility for industrial repair and low-volume analog designs.
Availability
KSC945OBU is available at Aetrix Electronics and suitable for audio preamplifiers, RF oscillator modules, DC motor drivers, and logic-level translation circuits requiring stable component supply and long-term obsolescence support.
Supply support for KSC945OBU 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 delivering energy-efficient power and sensing solutions for automotive, industrial, cloud, and consumer markets.
The KSC945OBU belongs to onsemi's legacy discrete transistor product line, engineered for reliability in analog signal conditioning, RF generation, and low-power switching applications across consumer and industrial electronics.
FAQ
What is the pin configuration of the KSC945OBU?
The KSC945OBU uses a standard TO-92 package with pinout: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector. This configuration is confirmed in the official onsemi datasheet (Publication Order Number KSC945/D, Rev. 3, June 2024) and matches the mechanical outline CASE 135AN. The KSC945OBU does not use center-collector orientation - that applies only to suffix "-C" variants.
Is the KSC945OBU RoHS compliant?
Yes, the KSC945OBU is Pb-free and RoHS compliant, as explicitly stated in the ordering information section of the onsemi datasheet: "TO−92 3 (Pb−Free)" and "KSC945OBU" listed under Pb-free bulk packaging. It meets EU Directive 2011/65/EU requirements for restricted hazardous substances.
What is the maximum operating temperature for the KSC945OBU?
The KSC945OBU has a maximum junction temperature (TJ) of 150°C and a storage temperature range of −55°C to +150°C, per the Absolute Maximum Ratings table in the onsemi datasheet. Derating begins above 25°C ambient at 2.0 mW/°C, limiting usable power dissipation in high-temperature environments.
Can the KSC945OBU replace the KSC945YTA?
No - KSC945YTA is discontinued (per Note 1 in the datasheet), while KSC945OBU remains orderable in bulk Pb-free packaging. Both share identical electrical specs and TO-92 package, but KSC945OBU is the active, supported version for new purchases and legacy design sustainment.
What is the typical noise figure of the KSC945OBU and at what conditions is it measured?
The KSC945OBU has a typical noise figure of 4.0 dB, measured at VCE = 6 V, IC = 0.5 mA, f = 1 kHz, and RS = 500 Ω, as specified in the Electrical Characteristics table of the onsemi datasheet. This value reflects its suitability for low-noise preamplifier stages where signal integrity is critical.
KSC945OBU 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:
- 70 @ 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
KSC945OBU FAQ
1.How can I place an order for KSC945OBU through Aetrix?
Please submit a Request for Quotation (RFQ) for KSC945OBU 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 KSC945OBU reliable?
The price and inventory of KSC945OBU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC945OBU is usually 5 days.
3.What payment methods are accepted for KSC945OBU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC945OBU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KSC945OBU?
KSC945OBU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KSC945OBU 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 KSC945OBU?
For technical support, including KSC945OBU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC945OBU requirements.
6.How does Aetrix verify that KSC945OBU is sourced from the original manufacturer or authorized distributors?
All KSC945OBU 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 KSC945OBU meets industry standards.
7.What is the process for return or replacement of KSC945OBU?
All KSC945OBU units undergo pre-shipment inspection (PSI). If there is an issue with KSC945OBU, 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 KSC945OBU part is unused and in its original packaging.
Return procedure for KSC945OBU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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