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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi KSA1220AYS

Name: KSA1220AYS
Brand: onsemi
SKU: KSA1220AYS
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSA1220AYS

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: KSA1220AYS.pdf

Description:: TRANS PNP 160V 1.2A TO-126

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSA1220AYS from ON Semiconductor is a PNP epitaxial silicon power transistor in TO-126 package, rated for −120 V V_CEO, −1.2 A DC collector current, and 20 W collector dissipation at T_C = 25°C. It delivers h_FE of 35–150 at I_C = −5 mA and supports audio and high-frequency power amplifier applications with f_T = 175 MHz.

For engineers reviewing the KSA1220AYS datasheet, pinout, applications, or equivalent options, key selection considerations include its complementary pairing with KSC2690/KSC2690A, −0.4 V to −0.7 V V_CE(sat) at I_C = −1 A, and safe operating area validated up to 10 ms pulse width under derated conditions.

Technical Context

This PNP bipolar junction transistor operates in linear and switching modes with verified DC current gain (h_FE) spanning 35–320 across two test conditions: I_C = −5 mA (h_FE1) and I_C = −0.3 A (h_FE2). Its −175 MHz f_T and 26 pF C_ob at V_CB = −10 V support stable high-frequency amplification up to VHF band.

The device features low saturation voltages: V_CE(sat) ≤ −0.7 V and V_BE(sat) ≤ −1.3 V at I_C = −1 A / I_B = −0.2 A. Its SOA curve is defined for both DC and pulsed operation (PW ≤ 10 ms, duty ≤ 50%), with thermal derating starting at T_C > 25°C per Figure 7 and Figure 8.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−120 V - Maximum allowable collector-emitter voltage before breakdown in common-emitter configuration
I_C (DC)	−1.2 A - Continuous collector current rating defining steady-state power handling capability
P_C (T_C=25°C)	20 W - Maximum power dissipation at case temperature of 25°C, requiring heatsink for full utilization
h_FE2	60–320 - DC current gain at I_C = −0.3 A, critical for bias stability in Class AB amplifier stages
f_T	175 MHz - Frequency at which small-signal current gain drops to unity, enabling VHF amplification
V_CE(sat)	−0.4 V to −0.7 V - Low saturation voltage at I_C = −1 A / I_B = −0.2 A, minimizing conduction loss in switching use
C_ob	26 pF - Output capacitance at V_CB = −10 V, directly impacting high-frequency gain roll-off and stability margin

Pinout & Package

Package: TO-126 - Three-lead plastic power package with integral metal tab for mechanical mounting and thermal conduction to heatsink. Dimensions: 16.10 × 13.06 × 4.2 mm (L × W × H), tab diameter ø3.20 mm.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitter terminal	Primary current exit path in PNP operation; connected to most positive rail in typical amplifier configurations
2 (Collector)	Collector terminal	Main current input node; electrically tied to heatsink tab in TO-126, requiring insulation if heatsink is grounded
3 (Base)	Control terminal	Current-controlled input governing collector-emitter conduction; requires negative base drive relative to emitter

Key Features

Feature	Design Value
Complementary Pairing	Explicitly designed as PNP complement to KSC2690/KSC2690A NPN transistors for push-pull output stages
High f_T	175 MHz bandwidth enables stable operation in audio power amplifiers and HF driver circuits up to ~100 MHz
Low V_CE(sat)	≤ −0.7 V at rated I_C/I_B reduces power loss and thermal stress in linear and quasi-saturated switching
SOA Validation	Defined safe operating area curves cover DC, 1 ms, 10 ms, and pulse-limited regions - essential for reliability in transient-loaded designs
Thermal Derating	Linear power derating from 20 W at T_C = 25°C to zero at T_C = 200°C per Figure 8, supporting robust thermal design

Applications

Audio Power Amplifier	High-Frequency Driver
Use Scenario: Output stage in stereo audio power amplifiers delivering 10–50 W into 4–8 Ω loads. IC Role / Device Role / Timing Role: PNP power transistor in complementary push-pull emitter-follower configuration. Use Value: Delivers low-distortion linear amplification with h_FE ≥ 60 at I_C = −0.3 A and V_CE(sat) ≤ −0.7 V, reducing crossover distortion.	Use Scenario: Final-stage driver in RF power amplifiers for VHF transmitters (30–100 MHz). IC Role / Device Role / Timing Role: High-current, high-gain active element in tuned Class C or AB amplifier topologies. Use Value: 175 MHz f_T and 26 pF C_ob enable stable gain and impedance matching without excessive neutralization.
DC Motor Control	Power Supply Regulator
Use Scenario: H-bridge or single-ended switch controlling 12–24 V brushed DC motors drawing ≤1 A continuous. IC Role / Device Role / Timing Role: High-side PNP switch in discrete motor driver circuits with base-current-limited turn-on. Use Value: −120 V V_CEO provides margin against inductive kickback; −0.4 V V_CE(sat) minimizes resistive heating during on-state.	Use Scenario: Pass transistor in linear regulated power supplies delivering up to 1.2 A at adjustable output voltages. IC Role / Device Role / Timing Role: Series pass element dissipating excess input-output differential voltage. Use Value: 20 W T_C-referenced power rating allows operation with modest heatsinking at ≤10 W dissipation in typical 5–12 V outputs.

Audio Power Amplifier

High-Frequency Driver

Use Scenario: Output stage in stereo audio power amplifiers delivering 10–50 W into 4–8 Ω loads.

IC Role / Device Role / Timing Role: PNP power transistor in complementary push-pull emitter-follower configuration.

Use Value: Delivers low-distortion linear amplification with h_FE ≥ 60 at I_C = −0.3 A and V_CE(sat) ≤ −0.7 V, reducing crossover distortion.

Use Scenario: Final-stage driver in RF power amplifiers for VHF transmitters (30–100 MHz).

IC Role / Device Role / Timing Role: High-current, high-gain active element in tuned Class C or AB amplifier topologies.

Use Value: 175 MHz f_T and 26 pF C_ob enable stable gain and impedance matching without excessive neutralization.

DC Motor Control

Power Supply Regulator

Use Scenario: H-bridge or single-ended switch controlling 12–24 V brushed DC motors drawing ≤1 A continuous.

IC Role / Device Role / Timing Role: High-side PNP switch in discrete motor driver circuits with base-current-limited turn-on.

Use Value: −120 V V_CEO provides margin against inductive kickback; −0.4 V V_CE(sat) minimizes resistive heating during on-state.

Use Scenario: Pass transistor in linear regulated power supplies delivering up to 1.2 A at adjustable output voltages.

IC Role / Device Role / Timing Role: Series pass element dissipating excess input-output differential voltage.

Use Value: 20 W T_C-referenced power rating allows operation with modest heatsinking at ≤10 W dissipation in typical 5–12 V outputs.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD122G	V_CEO = −100 V (lower), h_FE = 30–120 at I_C = −1 A, TO-220 package	Limited to lower-voltage supplies; higher thermal mass but no insulated tab	Select when V_IN ≤ 80 V and board layout accommodates TO-220 footprint
KSA992F	V_CEO = −160 V (higher), I_C = −1.5 A, f_T = 120 MHz, TO-126 package	Better voltage margin and current rating but reduced bandwidth vs. KSA1220AYS	Prefer for 100–150 V supply rails where gain-bandwidth trade-off favors voltage safety

Compared with MJD122G and KSA992F, the KSA1220AYS offers optimal balance of 120 V rating, 175 MHz f_T, and TO-126 thermal interface-making it especially suitable for compact audio amplifiers needing both bandwidth and moderate voltage headroom.

Availability

KSA1220AYS is available at Aetrix Electronics and suitable for audio power amplifiers, high-frequency drivers, DC motor control circuits, and linear power supply regulators requiring stable component supply and consistent parametric performance across production batches.

Supply support for KSA1220AYS 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensors, and logic devices for automotive, industrial, and consumer markets.

The KSA1220AYS belongs to ON Semiconductor's legacy power bipolar transistor family, engineered specifically for audio frequency and high-frequency linear amplification with emphasis on SOA integrity and thermal reliability in TO-126 packages.

FAQ

What is the maximum collector-emitter voltage rating for KSA1220AYS?

The KSA1220AYS has a maximum collector-emitter voltage (V_CEO) rating of −120 V at T_C = 25°C. This rating applies in common-emitter configuration with base open. Exceeding this voltage risks avalanche breakdown and permanent device failure. The KSA1220AYS datasheet confirms this value in the Absolute Maximum Ratings table and validates SOA limits up to this voltage under pulsed conditions.

Does KSA1220AYS have a complementary NPN transistor?

Yes, the KSA1220AYS is explicitly designated as the PNP complement to the KSC2690 and KSC2690A NPN transistors. This pairing is documented in the "Complement to KSC2690/KSC2690A" line of the original Fairchild datasheet. Matching h_FE ranges, voltage ratings, and TO-126 packaging enable symmetrical push-pull amplifier designs using KSA1220AYS and KSC2690A together.

What is the safe operating area (SOA) behavior of KSA1220AYS under pulsed conditions?

The KSA1220AYS SOA is characterized for pulse widths up to 10 ms with duty cycle ≤50%, as shown in Figure 6 of the datasheet. At I_C = −2.5 A (pulse rating), the maximum allowable V_CE drops to approximately −40 V for 10 ms pulses. The SOA boundary shifts leftward with increasing pulse duration due to thermal limitations, and derating is required above T_C = 25°C per Figure 7.

Can KSA1220AYS be used in switching applications?

Yes, the KSA1220AYS supports switching use with verified V_CE(sat) ≤ −0.7 V at I_C = −1 A / I_B = −0.2 A and fast minority-carrier lifetime enabling reasonable turn-on/turn-off times. However, it lacks specified t_on/t_off values; designers should validate switching waveforms and losses empirically. Its SOA must be respected during hard-switching transients.

What package type does KSA1220AYS use, and how is thermal management handled?

The KSA1220AYS uses the TO-126 package, featuring a metal tab that serves as the collector terminal and primary thermal path. Effective thermal management requires mounting the tab to an external heatsink using insulating hardware (e.g., mica washer + thermal grease) if the heatsink is not electrically isolated. The datasheet specifies 20 W power dissipation at T_C = 25°C, implying mandatory heatsinking for sustained operation above ~2–3 W.

KSA1220AYS Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 1.2 A

Voltage - Collector Emitter Breakdown (Max):: 160 V

Vce Saturation (Max) @ Ib, Ic:: 700mV @ 200mA, 1A

Current - Collector Cutoff (Max):: 1µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 160 @ 300mA, 5V

Power - Max:: 1.2 W

Frequency - Transition:: 175MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126

KSA1220AYS FAQ

1.How can I place an order for KSA1220AYS through Aetrix?

Please submit a Request for Quotation (RFQ) for KSA1220AYS 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 KSA1220AYS reliable?

The price and inventory of KSA1220AYS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSA1220AYS is usually 5 days.

3.What payment methods are accepted for KSA1220AYS?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSA1220AYS transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSA1220AYS?

KSA1220AYS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSA1220AYS 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 KSA1220AYS?

For technical support, including KSA1220AYS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSA1220AYS requirements.

6.How does Aetrix verify that KSA1220AYS is sourced from the original manufacturer or authorized distributors?

All KSA1220AYS 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 KSA1220AYS meets industry standards.

7.What is the process for return or replacement of KSA1220AYS?

All KSA1220AYS units undergo pre-shipment inspection (PSI). If there is an issue with KSA1220AYS, 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 KSA1220AYS part is unused and in its original packaging.

Return procedure for KSA1220AYS:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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