My Inquiry
My Account
onsemi KSC3953DS
- Part No.:
- KSC3953DS
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-225AA, TO-126-3
- Datasheet:
-
KSC3953DS.pdf
- Description:
- TRANS NPN 120V 0.2A TO-126-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,940
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
KSC3953DS from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for high-frequency video output stages in CRT displays, featuring VCEO = 120 V, fT = 400 MHz (typ.), IC = 200 mA (DC), VCE(sat) = 1.0 V at IC = 30 mA/IB = 3 mA, and Cre = 1.7 pF (typ.).
For engineers reviewing the KSC3953DS datasheet, pinout, applications, or equivalent options, this device is selected for high-voltage, medium-current switching and RF amplification where low reverse transfer capacitance and stable gain-bandwidth performance are critical.
Technical Context
The KSC3953DS operates as a general-purpose NPN bipolar junction transistor with a TO-126 package, optimized for video output driver circuits requiring high breakdown voltage and fast switching. Its fT of 400 MHz enables stable small-signal amplification up to VHF range, while its low Cre (1.7 pF) minimizes Miller feedback distortion in common-emitter configurations.
It supports DC collector currents up to 200 mA and pulsed currents up to 400 mA, with thermal design enabled by 8 W dissipation at TC = 25°C. The hFE classification (C: 40–80; D: 60–120) indicates binning for consistent gain matching in production video amplifier modules.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCBO / VCEO | 120 V - Supports operation in CRT horizontal deflection and video output stages with high-voltage swing without breakdown. |
| fT | 400 MHz (typ.) - Enables broadband amplification up to ~300 MHz with usable gain margin in video signal paths. |
| Cre | 1.7 pF (typ.) - Reduces Miller effect-induced phase shift and instability in high-gain common-emitter video drivers. |
| VCE(sat) | 1.0 V @ IC = 30 mA, IB = 3 mA - Ensures low conduction loss and minimal power dissipation in saturated switching applications. |
| hFE (Class C) | 40–80 - Provides predictable DC current gain for biasing stability in linear video output amplifiers. |
| PC (TC = 25°C) | 8 W - Allows high-power dissipation when mounted on heatsink, suitable for continuous-duty video output stage operation. |
Pinout & Package
Package: TO-126 (3-lead, through-hole, thermally enhanced plastic). Pin 1: Emitter; Pin 2: Collector; Pin 3: Base. Mounting tab (Collector-connected) enables direct heatsinking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Current sink terminal | Connected to ground or low-impedance return path; sets emitter bias reference point for linear operation. |
| 2 (Collector) | High-voltage output node | Connected to CRT video anode load or flyback transformer; electrically tied to metal tab for thermal conduction. |
| 3 (Base) | Control input | Receives drive current (e.g., from preceding pre-driver stage); requires precise IB to maintain linear VCE control. |
Key Features
| Feature | Design Value |
|---|---|
| High fT bandwidth | 400 MHz typical - Maintains flat gain response across NTSC/PAL video baseband (0–5.5 MHz) with headroom for harmonics. |
| Low Cre capacitance | 1.7 pF typical - Limits unwanted coupling between output and input, improving stability in high-gain video amplifiers. |
| 120 V VCEO rating | Withstands CRT video line voltage transients and flyback-induced spikes without avalanche conduction. |
| TO-126 thermal design | 8 W power dissipation at TC = 25°C - Enables reliable operation under sustained video output load without forced cooling. |
Applications
| CRT Video Output Stage | Horizontal Deflection Driver |
|---|---|
Use Scenario: Amplifying composite video signal before CRT cathode modulation in analog monitors and TVs. IC Role / Device Role / Timing Role: Linear NPN amplifier operating in Class-A or Class-AB mode with fixed emitter bias and collector-loaded output. Use Value: Delivers full-swing video amplitude with <1% harmonic distortion due to stable hFE and low Cre. | Use Scenario: Switching horizontal deflection yoke current in CRT scan circuits with high-voltage flyback recovery. IC Role / Device Role / Timing Role: Saturated-switch BJT driving inductive yoke load; conducts during active scan, cuts off during retrace. Use Value: Withstands 120 V VCEO and dissipates 8 W with heatsink, enabling robust 15.734 kHz switching without thermal runaway. |
| RF Signal Amplifier | Medium-Power Switching Regulator |
Use Scenario: Low-noise small-signal amplification in VHF-band receivers (e.g., TV tuners, FM front-ends). IC Role / Device Role / Timing Role: Common-emitter amplifier biased for optimal fT utilization and noise figure below 3 dB at 100 MHz. Use Value: 400 MHz fT ensures >20 dB gain at 100 MHz, supporting wideband IF amplification with minimal phase distortion. | Use Scenario: Primary switch in offline DC-DC converters delivering 5–12 V at ~500 mA for auxiliary supplies. IC Role / Device Role / Timing Role: Medium-speed switching transistor in quasi-resonant or PWM-controlled flyback topology. Use Value: 1.0 V VCE(sat) and 200 mA IC rating enable >85% efficiency at 50–100 kHz switching with minimal conduction loss. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar NPN high-voltage, medium-frequency transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MJD127G | VCEO = 100 V (lower), fT = 3 MHz (much lower), TO-220 package, higher PC = 30 W | Better for high-power linear regulation but unsuitable for video bandwidth or CRT output | Select only if thermal budget dominates over frequency response and voltage margin is relaxed. |
| KSC2383Y | VCEO = 160 V (higher), fT = 200 MHz (lower), same TO-126, hFE = 120–240 (wider spread) | Preferred for ultra-high-voltage CRT deflection but sacrifices video bandwidth fidelity | Choose when >120 V standoff is mandatory and 400 MHz fT is not required. |
Compared with MJD127G and KSC2383Y, the KSC3953DS uniquely balances 120 V breakdown, 400 MHz fT, and TO-126 thermal-mechanical compatibility-making it the only option validated for CRT video output stages demanding simultaneous high voltage, high speed, and moderate power handling.
Availability
KSC3953DS is available at Aetrix Electronics and suitable for CRT display video output stages, horizontal deflection drivers, RF signal amplifiers, and medium-power switching regulators requiring stable component supply and long-lifecycle support.
Supply support for KSC3953DS 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 manufacturer specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.
The KSC3953DS belongs to Fairchild's legacy high-frequency NPN transistor product line, engineered specifically for analog video signal integrity and CRT-based display systems requiring high-voltage tolerance and broadband gain.
FAQ
What is the maximum continuous collector current for the KSC3953DS?
The KSC3953DS supports a maximum DC collector current (IC) of 200 mA at Ta = 25°C. Derating applies above ambient temperature; at TC = 25°C with heatsink, it handles up to 400 mA pulsed (ICP). This rating ensures safe operation in CRT video output loads without thermal saturation.
Is the KSC3953DS pin-compatible with other TO-126 NPN transistors like the KSC1845?
No-the KSC3953DS has Emitter–Collector–Base pinout (1–2–3), whereas the KSC1845 uses Emitter–Base–Collector (1–3–2). Swapping them without board revision causes immediate circuit failure. Always verify pin assignment using the official Fairchild KSC3953DS datasheet diagram before substitution.
Does the KSC3953DS have built-in protection features such as ESD or thermal shutdown?
No-the KSC3953DS is a bare-die bipolar transistor with no integrated protection circuitry. It relies entirely on external design safeguards: series base resistors, emitter degeneration, clamping diodes, and heatsinking. System-level protection must be implemented per application requirements.
What is the typical hFE range for the KSC3953DS at VCE = 10 V and IC = 100 mA?
At VCE = 10 V and IC = 100 mA, the KSC3953DS exhibits hFE2 ranging from 20 to 120 depending on grade (C or D bin). The D-grade version guarantees minimum hFE2 = 60, making it preferred for designs requiring tighter gain consistency in video amplifier bias networks.
Can the KSC3953DS be used in modern LCD or OLED display backlight drivers?
No-the KSC3953DS was engineered for analog CRT video signal chains and lacks the switching speed, gate-drive compatibility, or integrated control logic needed for LED backlight PWM drivers. Modern applications require MOSFETs or dedicated LED driver ICs with digital interfaces and thermal foldback.
KSC3953DS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-225AA, TO-126-3
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 200 mA
- Voltage - Collector Emitter Breakdown (Max):
- 120 V
- Vce Saturation (Max) @ Ib, Ic:
- 1V @ 3mA, 30mA
- Current - Collector Cutoff (Max):
- 100nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 60 @ 10mA, 10V
- Power - Max:
- 1.3 W
- Frequency - Transition:
- 400MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-126-3
KSC3953DS FAQ
1.How can I place an order for KSC3953DS through Aetrix?
Please submit a Request for Quotation (RFQ) for KSC3953DS 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 KSC3953DS reliable?
The price and inventory of KSC3953DS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC3953DS is usually 5 days.
3.What payment methods are accepted for KSC3953DS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC3953DS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KSC3953DS?
KSC3953DS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KSC3953DS 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 KSC3953DS?
For technical support, including KSC3953DS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC3953DS requirements.
6.How does Aetrix verify that KSC3953DS is sourced from the original manufacturer or authorized distributors?
All KSC3953DS 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 KSC3953DS meets industry standards.
7.What is the process for return or replacement of KSC3953DS?
All KSC3953DS units undergo pre-shipment inspection (PSI). If there is an issue with KSC3953DS, 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 KSC3953DS part is unused and in its original packaging.
Return procedure for KSC3953DS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
KSC3953DS Tags
-
MMBT3906LT1G
onsemi
-
MMBT3904-7-F
Diodes Incorporated
-
MMBT3904LT1G
onsemi
-
MMBT3906-7-F
Diodes Incorporated
-
MMBT3904-TP
Micro Commercial Co
-
MMBT2222A-7-F
Diodes Incorporated
-
BC846BLT1G
onsemi
-
BC847B,215
Nexperia USA Inc.
-
SMMBT3904LT1G
onsemi
-
MMBT2222A-TP
Micro Commercial Co
-
MMBTA06LT1G
onsemi
-
MMBT2222ALT1G
onsemi
Tech Hub
Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
