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onsemi KSC2785LTA
- Part No.:
- KSC2785LTA
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 Short Body
- Datasheet:
-
KSC2785LTA.pdf
- Description:
- TRANS NPN 50V 0.15A TO-92S
- Quantity:
- Payment:
- Shipping:
Inventory:3,011
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Product details
Overview
KSC2785LTA from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for audio frequency amplification and high-frequency oscillator circuits, with VCBO = 60 V, VCEO = 50 V, IC = 150 mA, hFE = 350–700 (L-class), and fT = 300 MHz.
For engineers reviewing the KSC2785LTA datasheet, pinout, applications, or equivalent options, this device supports low-noise analog gain stages, RF oscillator biasing, and general-purpose switching where DC current gain stability and high-frequency response are required.
Technical Context
The KSC2785LTA operates as a medium-power, medium-speed NPN bipolar junction transistor optimized for linear amplification and oscillation up to ~300 MHz. Its L-class hFE bin (350–700) ensures consistent gain in emitter-follower and common-emitter configurations at IC = 1.0 mA and VCE = 6 V.
It features low saturation voltage (VCE(sat) ≤ 0.3 V at IC = 100 mA/IB = 10 mA), low output capacitance (Cob = 2.5 pF at VCB = 6 V), and low noise figure (NF = 4.0 dB at f = 1 kHz, RS = 500 Ω), making it suitable for low-distortion audio preamplifiers and stable LC tank oscillators.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCBO | 60 V - Maximum reverse-biased collector-base voltage before breakdown; sets safe operating range in tuned amplifier stages. |
| VCEO | 50 V - Maximum collector-emitter voltage under open-base condition; defines upper rail limit in common-emitter designs. |
| hFE (L-class) | 350–700 - Confirmed DC current gain bin; enables predictable biasing without gain trimming in production audio gain blocks. |
| fT | 300 MHz - Current gain–bandwidth product; supports stable operation in VHF oscillator and RF buffer applications. |
| Cob | 2.5 pF - Output capacitance at VCB = 6 V; minimizes Miller effect in high-gain, high-frequency amplifier topologies. |
| NF | 4.0 dB - Noise figure at 1 kHz with 500 Ω source; ensures low added noise in microphone preamp and signal-chain front-end use. |
Pinout & Package
Package: TO-92S - 3-lead plastic through-hole package with standardized lead spacing (1.27 mm pitch), compact footprint (4.00 × 3.72 × 2.86 mm), and JEDEC-compliant thermal profile for manual or wave-solder assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Current sink terminal | Connected to ground or low-impedance return path; polarity-sensitive for correct BJT biasing and current flow direction. |
| 2 (Collector) | Current source terminal | Drives load or feeds next stage; requires proper decoupling and voltage margin relative to VCBO/VCEO limits. |
| 3 (Base) | Control input terminal | Accepts forward-bias current to modulate collector current; sensitive to ESD and requires series resistance in digital drive applications. |
Key Features
| Feature | Design Value |
|---|---|
| L-class hFE binning | Guaranteed hFE 350–700 at VCE = 6 V, IC = 1.0 mA - eliminates need for external gain calibration in production audio modules. |
| Low VCE(sat) | ≤ 0.3 V at IC = 100 mA/IB = 10 mA - reduces conduction loss and self-heating in Class-A amplifier output stages. |
| High fT | 300 MHz - enables reliable operation in 27 MHz, 40 MHz, and 100 MHz oscillator tanks without gain roll-off. |
| Low Cob | 2.5 pF - maintains phase margin and tuning stability in Colpitts and Hartley oscillator feedback networks. |
Applications
| Audio Preamp Stage | RF Local Oscillator |
|---|---|
Use Scenario: Low-noise amplification of electret microphone or line-level signals in portable audio devices. 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 stable L-bin hFE ensure consistent SNR and gain matching across production units. | Use Scenario: Fundamental-mode LC oscillator generating 27–100 MHz clock signals for IF mixing or PLL reference. IC Role / Device Role / Timing Role: Active device in Colpitts topology providing phase-shifted gain at resonant frequency. Use Value: 300 MHz fT and 2.5 pF Cob support stable oscillation with minimal frequency drift and low harmonic content. |
| Complementary Pair Driver | General-Purpose Switch |
Use Scenario: Upper-side driver in complementary NPN/PNP push-pull output stage for headphone amplifiers. IC Role / Device Role / Timing Role: High-gain, medium-current switch paired with KSA1175 PNP transistor. Use Value: Matched VCBO (60 V) and complementary hFE range enable symmetrical clipping and reduced crossover distortion. | Use Scenario: On/off control of LED indicators, relay coils, or small solenoids in industrial control panels. IC Role / Device Role / Timing Role: Saturated switch with base-driven turn-on and passive pull-down. Use Value: 150 mA IC rating and ≤0.3 V VCE(sat) minimize power dissipation and heat rise in continuous-duty switching. |
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 |
|---|---|---|---|
| BC548C | Lower fT (300 MHz typical but not guaranteed; max rated 150 MHz), hFE 420–800, VCBO = 30 V | Not suitable for >30 MHz oscillators or 50 V rail applications due to lower voltage and unguaranteed fT | Select only for low-voltage (<25 V), sub-10 MHz linear amplification where cost is primary constraint |
| MPSA18 | Higher VCEO (50 V same), hFE 100–300 (no L-bin), fT = 600 MHz, Cob = 3.5 pF | Better high-frequency gain but wider hFE spread increases bias sensitivity in production gain stages | Prefer for wideband RF amplifiers where gain consistency is less critical than bandwidth |
Compared with BC548C and MPSA18, the KSC2785LTA uniquely combines guaranteed L-bin hFE (350–700), 60 V VCBO, and validated 300 MHz fT-making it optimal for production-grade audio preamps and stable VHF oscillators requiring both voltage headroom and gain predictability.
Availability
KSC2785LTA is available at Aetrix Electronics and suitable for audio preamplifier modules, RF oscillator circuits, complementary pair drivers, and general-purpose switching applications requiring stable component supply and long-term manufacturability.
Supply support for KSC2785LTA 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 power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.
The KSC2785LTA belongs to Fairchild's legacy small-signal transistor family, engineered for high-fidelity audio amplification and stable RF oscillator design in consumer and industrial equipment.
FAQ
What is the hFE classification for KSC2785LTA?
The KSC2785LTA is specifically binned to the L-class hFE range of 350–700 at VCE = 6 V and IC = 1.0 mA. This tight gain distribution is confirmed in the Fairchild datasheet Rev. A2 and enables repeatable biasing in production audio amplifier circuits without individual gain trimming. The 'L' suffix in KSC2785LTA directly denotes this guaranteed hFE bin.
Is KSC2785LTA pin-compatible with KSC2785Y or KSC2785O?
Yes - all KSC2785 variants (including KSC2785LTA, KSC2785Y, and KSC2785O) share identical TO-92S packaging and pinout (1: Emitter, 2: Collector, 3: Base). The suffixes denote only hFE binning (L = 350–700, Y = 120–240, O = 70–140); electrical pin functions and mechanical layout are fully interchangeable.
What is the maximum operating temperature for KSC2785LTA?
The KSC2785LTA has a maximum junction temperature (TJ) of 150°C and a storage temperature range of –55°C to +150°C. Derating is required above 25°C ambient: power dissipation must be reduced linearly beyond 25°C at 2.0 mW/°C, per the datasheet's thermal resistance specification (RθJA ≈ 500°C/W).
Does KSC2785LTA support RF oscillator applications?
Yes - the KSC2785LTA is explicitly designated for "High Frequency OSC." in its official description, and its 300 MHz fT, 2.5 pF Cob, and low NF (4.0 dB) are validated for stable operation in fundamental-mode Colpitts and Hartley oscillators up to 100 MHz. Designers should maintain proper VCB bias and minimize stray capacitance for optimal phase noise performance.
What is the complement transistor for KSC2785LTA?
The KSA1175 is the designated complementary PNP transistor for KSC2785LTA, as stated in the original Fairchild documentation. Both share matched VCBO (60 V), similar hFE ranges, and TO-92S packaging - enabling balanced push-pull and differential pair designs in audio and signal conditioning circuits using KSC2785LTA.
KSC2785LTA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 Short Body
- Packaging:
- Tape & Box (TB)
- 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-92S
KSC2785LTA FAQ
1.How can I place an order for KSC2785LTA through Aetrix?
Please submit a Request for Quotation (RFQ) for KSC2785LTA 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 KSC2785LTA reliable?
The price and inventory of KSC2785LTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC2785LTA is usually 5 days.
3.What payment methods are accepted for KSC2785LTA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC2785LTA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KSC2785LTA?
KSC2785LTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KSC2785LTA 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 KSC2785LTA?
For technical support, including KSC2785LTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC2785LTA requirements.
6.How does Aetrix verify that KSC2785LTA is sourced from the original manufacturer or authorized distributors?
All KSC2785LTA 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 KSC2785LTA meets industry standards.
7.What is the process for return or replacement of KSC2785LTA?
All KSC2785LTA units undergo pre-shipment inspection (PSI). If there is an issue with KSC2785LTA, 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 KSC2785LTA part is unused and in its original packaging.
Return procedure for KSC2785LTA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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