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onsemi KSC1173OTU
- Part No.:
- KSC1173OTU
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-220-3
- Datasheet:
-
KSC1173OTU.pdf
- Description:
- TRANS NPN 30V 3A TO-220-3
- Quantity:
- Payment:
- Shipping:
Inventory:7,060
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Product details
Overview
KSC1173OTU from Fairchild Semiconductor is an NPN epitaxial silicon power transistor designed for low-frequency power amplification and linear power regulation. It delivers 3 A collector current, 10 W collector dissipation at TC = 25°C, and supports 30 V collector-emitter breakdown voltage. It is commonly used in DC-DC linear regulators and audio output stages where thermal stability and rugged SOA are required.
For engineers reviewing the KSC1173OTU datasheet, pinout, applications, or equivalent options, key selection criteria include safe operating area (SOA) under pulse conditions, hFE consistency across IC = 0.5–2.5 A, VCE(sat) ≤ 0.8 V at IC = 2 A/IB = 0.2 A, and TO-220 thermal derating behavior above 25°C case temperature.
Technical Context
This device operates as a medium-power, low-frequency bipolar junction transistor with epitaxial base construction for improved gain uniformity and switching consistency. Its DC current gain ranges from 70 to 240 depending on IC, and it exhibits fT = 100 MHz at VCE = 2 V, IC = 0.5 A - sufficient for audio and switching regulator error amplifiers but not RF applications.
The KSC1173OTU features complementary pairing with KSA473 (PNP), enabling push-pull amplifier topologies. Its SOA curve includes thermal-limited and secondary breakdown boundaries, with pulse capability up to 50 ms at reduced voltage/current - critical for overload protection in linear supplies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IC (Max) | 3 A - supports continuous load currents in linear regulators and Class-A/B audio drivers |
| PC (TC=25°C) | 10 W - requires heatsinking for operation above ambient; derates linearly to zero at TC ≈ 175°C |
| BVCEO | 30 V - limits use to ≤24 V rail systems with margin; unsuitable for 48 V industrial buses |
| hFE (IC=0.5A) | 70–140 - enables stable biasing in emitter-follower and series-pass configurations |
| VCE(sat) (IC=2A) | 0.3–0.8 V - determines conduction loss and thermal rise in high-current linear pass elements |
| fT | 100 MHz - confirms adequate small-signal bandwidth for error amplifier compensation in SMPS feedback loops |
| Cob | 35 pF @ VCB=10 V - impacts high-frequency stability in multi-stage amplifiers and affects Miller effect in switching applications |
Pinout & Package
Package: TO-220 (3-lead, straight lead, insulated tab). Mounting requires electrically isolated heatsink interface due to collector-connected tab.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Base) | Control input terminal | Receives forward-biased current to drive transistor into active/saturation; requires current-limiting resistor in most applications |
| 2 (Collector) | High-current output node | Electrically connected to metal tab; must be isolated from heatsink unless circuit ground reference permits |
| 3 (Emitter) | Current return path | Serves as common reference for base drive and load return; often tied to system ground or negative rail |
Key Features
| Feature | Design Value |
|---|---|
| Complementary PNP pair | Validated match with KSA473 for push-pull output stages and differential amplifiers |
| Safe Operating Area (SOA) | Defined for DC, 1 ms, 10 ms, and 50 ms pulses - enables robust overload handling in regulated supplies |
| Low VCE(sat) | 0.3 V typical at IC = 2 A - reduces conduction loss and improves efficiency in linear pass elements |
| Epitaxial base structure | Ensures tight hFE distribution (O/Y classification) and consistent gain across production lots |
| TO-220 thermal performance | RθJC = 1.5°C/W (typical) - allows 6.7 A max DC current with 15°C/W heatsink at TA = 25°C |
Applications
| Linear Voltage Regulators | Audio Power Amplifiers |
|---|---|
Use Scenario: Used as series pass element in adjustable 3–24 V linear regulators delivering up to 3 A output. IC Role / Device Role / Timing Role: NPN series pass transistor controlling output voltage via base bias from error amplifier. Use Value: Low VCE(sat) minimizes dropout voltage; SOA supports short-circuit foldback without second breakdown. | Use Scenario: Employed in Class-AB output stage of 10–20 W audio amplifiers driving 4–8 Ω speakers. IC Role / Device Role / Timing Role: Output driver transistor delivering peak current while maintaining linearity and thermal stability. Use Value: High hFE and low Cob reduce distortion and improve high-frequency response up to 20 kHz. |
| DC Motor Drivers | Power Supply Protection Circuits |
Use Scenario: Drives brushed DC motors (12–24 V, ≤2.5 A) in industrial actuators and HVAC dampers. IC Role / Device Role / Timing Role: Single-ended switch in linear or PWM-controlled H-bridge half-bridge configuration. Use Value: Rugged SOA withstands motor inductive kickback; TO-220 package enables direct heatsink mounting. | Use Scenario: Implements overcurrent limiting and crowbar protection in lab bench power supplies. IC Role / Device Role / Timing Role: Fast-turn-on current-sensing switch triggering SCR latch or shutdown logic. Use Value: Low BVEBO (5 V) and fast turn-on support precise current threshold detection with minimal external components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar NPN power transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MJD122G | Higher BVCEO (100 V), lower hFE (20–70), TO-263 package | Better suited for 48 V systems; less gain stability at low IC | Choose MJD122G when higher voltage rating and surface-mount assembly are required |
| TIP31C | Same TO-220 package; lower PC (40 W), higher BVCEO (100 V), wider hFE spread (10–50) | More voltage headroom but poorer gain control and thermal margin at 3 A | Choose TIP31C only if 100 V rating is mandatory and gain variation is acceptable |
Compared with MJD122G and TIP31C, the KSC1173OTU offers superior hFE consistency at mid-current levels and optimized SOA for 24 V linear regulation - making it preferred for precision analog power stages where thermal predictability and gain stability outweigh raw voltage rating.
Availability
KSC1173OTU is available at Aetrix Electronics and suitable for linear voltage regulators, audio power amplifiers, DC motor drivers, and power supply protection circuits requiring stable component supply and long-term industrial availability.
Supply support for KSC1173OTU 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 devices before its acquisition by ON Semiconductor in 2016.
The KSC1173OTU belongs to Fairchild's legacy NPN power transistor family, engineered for reliability in linear power control and low-frequency amplification where SOA integrity and thermal robustness are critical.
FAQ
What is the maximum continuous collector current for KSC1173OTU?
The KSC1173OTU supports a maximum continuous collector current of 3 A at TC = 25°C. Operation at this current requires adequate heatsinking to maintain junction temperature below 150°C. Derating is necessary above 25°C case temperature per Figure 7 in the datasheet, reaching zero allowable current at approximately 175°C TC.
Is KSC1173OTU pin-compatible with KSA473?
No, KSC1173OTU is not pin-compatible with KSA473. While they are complementary NPN/PNP pairs, KSC1173OTU uses TO-220 pinout (1=Base, 2=Collector, 3=Emitter), whereas KSA473 has reversed emitter-collector assignment in the same package. Direct substitution without board revision will cause circuit failure.
What is the typical DC current gain (hFE) of KSC1173OTU at IC = 2.5 A?
The KSC1173OTU exhibits hFE2 = 25–240 at VCE = 2 V and IC = 2.5 A, depending on the O or Y classification bin. The Y-grade part guarantees minimum hFE of 120 under these conditions, making it suitable for designs requiring predictable gain at high current.
Does KSC1173OTU have avalanche rating or ruggedness specification?
The KSC1173OTU datasheet does not specify rated avalanche energy or ruggedness. Its Safe Operating Area curve (Figure 6) defines operational limits under transient conditions, but no guaranteed single-pulse avalanche capability is provided. Designers should avoid operation beyond SOA boundaries and implement external clamping for inductive loads.
Can KSC1173OTU be used in switching applications?
Yes, KSC1173OTU can be used in low-frequency switching applications (≤100 kHz) such as PWM motor control or SMPS error amplifiers, but it is not optimized for high-speed switching. Its Cob = 35 pF and fT = 100 MHz limit efficiency and switching speed compared to modern MOSFETs or RF BJTs.
KSC1173OTU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Tube
- Product Status:
- Obsolete
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 3 A
- Voltage - Collector Emitter Breakdown (Max):
- 30 V
- Vce Saturation (Max) @ Ib, Ic:
- 800mV @ 200mA, 2A
- Current - Collector Cutoff (Max):
- 1µA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 70 @ 500mA, 2V
- Power - Max:
- 10 W
- Frequency - Transition:
- 100MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-3
KSC1173OTU FAQ
1.How can I place an order for KSC1173OTU through Aetrix?
Please submit a Request for Quotation (RFQ) for KSC1173OTU 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 KSC1173OTU reliable?
The price and inventory of KSC1173OTU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC1173OTU is usually 5 days.
3.What payment methods are accepted for KSC1173OTU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC1173OTU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for KSC1173OTU?
KSC1173OTU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your KSC1173OTU 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 KSC1173OTU?
For technical support, including KSC1173OTU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC1173OTU requirements.
6.How does Aetrix verify that KSC1173OTU is sourced from the original manufacturer or authorized distributors?
All KSC1173OTU 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 KSC1173OTU meets industry standards.
7.What is the process for return or replacement of KSC1173OTU?
All KSC1173OTU units undergo pre-shipment inspection (PSI). If there is an issue with KSC1173OTU, 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 KSC1173OTU part is unused and in its original packaging.
Return procedure for KSC1173OTU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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