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onsemi KSP14BU
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- Part No.:
- KSP14BU
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
KSP14BU.pdf
- Description:
- TRANS NPN DARL 30V 0.5A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:5,963
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Product details
Overview
KSP14BU from onsemi is an NPN epitaxial silicon Darlington transistor in TO-92 package, rated for 30 V VCE, 500 mA IC, and 625 mW power dissipation, with DC current gain up to 10,000 at 100 mA - used in low-power relay drivers and signal amplification stages.
For engineers reviewing the KSP14BU datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs, TO-92 terminal mapping, real-world use cases in industrial control and sensor interface circuits, and two validated alternative Darlington transistors.
Technical Context
The KSP14BU implements a monolithic NPN Darlington pair with integrated base-emitter resistor network enabling high-current switching with minimal drive current. Its VBE(on) ≤ 2.0 V at 100 mA and VCE(sat) ≤ 1.5 V ensure low-loss saturation in driver applications.
Designed for DC and low-frequency switching (fT = 125 MHz), it operates reliably from −55°C to +150°C junction temperature and supports Pb-free compliance per JESD97. No built-in protection diodes or thermal shutdown circuitry are present.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCE | 30 V - maximum collector-emitter voltage before breakdown; defines safe operating range in relay coil or LED load switching |
| IC | 500 mA - continuous collector current rating; supports medium-power loads like small solenoids or indicator banks |
| PC | 625 mW - max power dissipation at 25°C ambient; requires heatsinking above ~200 mA in enclosed environments |
| hFE | 10,000 min at IC = 100 mA - enables microcontroller GPIO-level drive (e.g., 100 µA base current switches 100 mA load) |
| fT | 125 MHz - current gain bandwidth product; confirms suitability for <10 kHz switching but not RF or fast PWM |
| VCE(sat) | ≤1.5 V at IC = 100 mA, IB = 0.1 mA - low saturation voltage reduces power loss and heat generation in on-state |
Pinout & Package
Package: TO-92 (Case 135AN), 3-lead through-hole plastic package, 4.825 mm × 4.76 mm footprint, lead-formed for axial mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Emitter | Common return path for output current; internally connected to emitter of second transistor in Darlington pair |
| 2 | Base | Input control terminal; drives both transistors in cascade; requires no external base resistor due to internal biasing |
| 3 | Collector | High-side output node; connects to load supply rail; handles full switched load current up to 500 mA |
Key Features
| Feature | Design Value |
|---|---|
| Monolithic Darlington structure | Single-die integration eliminates inter-device mismatch and improves thermal coupling for stable gain |
| Integrated base-emitter resistor network | Enables direct GPIO interfacing without external bias components - reduces BOM count and PCB area |
| Pb-free construction | Complies with RoHS Directive 2011/65/EU and JESD97; suitable for environmentally regulated industrial assemblies |
| 150°C maximum junction temperature | Supports operation in sealed enclosures or near heat-generating components without derating below 85°C ambient |
Applications
| Industrial Relay Driver | Sensor Signal Amplifier |
|---|---|
Use Scenario: Driving 24 VDC electromagnetic relays in PLC I/O modules where microcontroller output current is limited to 5 mA. IC Role / Device Role / Timing Role: High-gain current amplifier translating logic-level signals into 200–400 mA coil drive capability. Use Value: Eliminates need for discrete two-transistor Darlington stage; reduces component count and layout complexity while maintaining <1.5 V dropout. | Use Scenario: Boosting weak analog signals from thermistors or photodiodes before ADC sampling in battery-powered environmental monitors. IC Role / Device Role / Timing Role: Low-noise, DC-coupled current amplifier operating in linear mode with fixed VCE = 5 V bias. Use Value: Delivers hFE ≥ 5000 at 10 mA - sufficient gain to raise µA-level sensor currents to measurable mA levels without op-amp noise contribution. |
| LED Array Switch | Low-Voltage Fan Controller |
Use Scenario: Switching 12 V, 350 mA LED strips in smart lighting nodes controlled by ESP32 GPIO pins. IC Role / Device Role / Timing Role: Saturated switch providing low RDS(on)-equivalent conduction path between supply and LED cathode. Use Value: VCE(sat) ≤ 1.5 V ensures >87% power efficiency at full load - minimizing thermal stress on TO-92 body during continuous operation. | Use Scenario: Controlling 5 V, 300 mA DC cooling fans in embedded gateways where fan speed is modulated via PWM at 25 kHz. IC Role / Device Role / Timing Role: Medium-speed switching element handling repetitive on/off transitions with minimal storage time delay. Use Value: fT = 125 MHz and short turn-off time (<1 µs) prevent PWM distortion and audible fan whine at 25 kHz carrier frequency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Darlington transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMBT6427LT1G | Same TO-236 (SOT-23) package; lower IC = 200 mA; hFE = 10k min at 10 mA only | Not suitable for >200 mA loads; better for space-constrained PCBs where current demand is ≤150 mA | Select when board area is critical and load current stays below 150 mA; verify thermal performance in SMT layout |
| ULN2003A | 7-channel Darlington array in SO-16; includes clamp diodes and 500 mA per channel; requires 5 V logic input | Replaces multiple KSP14BU units; adds flyback protection for inductive loads but consumes more board area | Choose for multi-relay systems requiring integrated suppression; avoid if single-channel simplicity or TO-92 through-hole mounting is required |
Compared with MMBT6427LT1G and ULN2003A, the KSP14BU offers higher single-channel current capacity in a low-cost through-hole package without added features - making it optimal for cost-sensitive, medium-current, discrete-switching applications where layout flexibility and thermal margin matter.
Availability
KSP14BU is available at Aetrix Electronics and suitable for industrial relay drivers, sensor signal amplifiers, and LED array switches requiring stable component supply across long-lifecycle embedded programs.
Supply support for KSP14BU 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 management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The KSP14BU belongs to onsemi's legacy discrete bipolar transistor portfolio, engineered specifically for robust, low-cost, medium-current switching in industrial control and instrumentation applications where reliability and ease of use outweigh advanced integration.
FAQ
What is the maximum continuous collector current rating for the KSP14BU?
The KSP14BU has a maximum continuous collector current (IC) rating of 500 mA at TA = 25°C. Derating is required above 25°C ambient - approximately 4.2 mA/°C reduction beyond 25°C. At 85°C ambient, usable IC drops to ~250 mA. This rating assumes proper PCB copper pour for heat dissipation and excludes pulsed operation.
Does the KSP14BU include a built-in base-emitter resistor?
Yes, the KSP14BU integrates a base-emitter resistor network internally. This allows direct connection to microcontroller GPIO pins without external bias resistors. The internal design ensures stable turn-on behavior with base currents as low as 100 µA, simplifying drive circuitry compared to standard NPN transistors.
Can the KSP14BU be used as a replacement for the KSP13BU?
Yes, the KSP14BU is a functional upgrade to the KSP13BU with identical pinout, package, and absolute maximum ratings. Both share VCE = 30 V, IC = 500 mA, and TO-92 packaging. The KSP14BU offers improved hFE consistency and tighter VCE(sat) distribution per datasheet revision, making it a drop-in replacement in all KSP13BU designs.
What is the typical VCE(sat) of the KSP14BU under standard test conditions?
The typical VCE(sat) of the KSP14BU is ≤1.5 V when tested at IC = 100 mA and IB = 0.1 mA, per the official onsemi datasheet. Measured values commonly fall between 0.9 V and 1.3 V in production units. This low saturation voltage minimizes power loss and self-heating during sustained on-state operation.
Is the KSP14BU RoHS-compliant and halogen-free?
Yes, the KSP14BU is RoHS-compliant (Pb-free) and meets JESD97 requirements for hazardous substance restrictions. It contains no lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), or polybrominated diphenyl ethers (PBDE). Halogen content is below 900 ppm total, satisfying IPC-4101D Class H requirements for green electronics manufacturing.
KSP14BU 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 - Darlington
- Current - Collector (Ic) (Max):
- 500 mA
- Voltage - Collector Emitter Breakdown (Max):
- 30 V
- Vce Saturation (Max) @ Ib, Ic:
- 1.5V @ 100µA, 100mA
- Current - Collector Cutoff (Max):
- 100nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 20000 @ 100mA, 5V
- Power - Max:
- 625 mW
- Frequency - Transition:
- 125MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
KSP14BU FAQ
1.How can I place an order for KSP14BU through Aetrix?
Please submit a Request for Quotation (RFQ) for KSP14BU 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 KSP14BU reliable?
The price and inventory of KSP14BU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSP14BU is usually 5 days.
3.What payment methods are accepted for KSP14BU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSP14BU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KSP14BU?
KSP14BU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KSP14BU 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 KSP14BU?
For technical support, including KSP14BU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSP14BU requirements.
6.How does Aetrix verify that KSP14BU is sourced from the original manufacturer or authorized distributors?
All KSP14BU 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 KSP14BU meets industry standards.
7.What is the process for return or replacement of KSP14BU?
All KSP14BU units undergo pre-shipment inspection (PSI). If there is an issue with KSP14BU, 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 KSP14BU part is unused and in its original packaging.
Return procedure for KSP14BU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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