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

onsemi KSD1691YSTSTU

Name: KSD1691YSTSTU
Brand: onsemi
SKU: KSD1691YSTSTU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSD1691YSTSTU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: KSD1691YSTSTU.pdf

Description:: TRANS NPN 60V 5A TO-126-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSD1691YSTSTU from onsemi is an NPN epitaxial silicon power transistor in TO-126-3LD package, rated for 60 V V_CEO, 5 A continuous collector current, and 1.3 W power dissipation at T_A = 25 °C. It delivers low V_CE(sat) (0.1–0.3 V at I_C = 2 A, I_B = 0.2 A) and high h_FE (100–400 at I_C = 2 A), enabling efficient switching in DC motor drivers and relay drivers.

For engineers reviewing the KSD1691YSTSTU datasheet, pinout, applications, or equivalent options, key selection criteria include verified saturation voltage, DC current gain grading (Y-grade h_FE2 = 160–320), thermal derating behavior, and complementary pairing with KSB1151 for push-pull output stages.

Technical Context

This device operates as a medium-power, general-purpose NPN bipolar junction transistor optimized for linear and switching applications where low saturation voltage and robust pulse current capability (I_CP = 8 A, PW ≤ 10 ms, duty ≤ 50%) are required. Its TO-126-3LD package provides direct case-to-heatsink thermal path with 20 W power dissipation at T_C = 25 °C.

The KSD1691YSTSTU exhibits graded h_FE performance: h_FE1 ≥ 60 at I_C = 0.1 A, h_FE2 = 160–320 (Y-grade) at I_C = 2 A, and h_FE3 ≥ 50 at I_C = 5 A - supporting stable biasing across wide load ranges. Turn-on time (0.2–1 µs) and storage time (1.1–2.5 µs) are specified under defined pulsed test conditions (V_CC = 10 V, R_L = 5 kΩ).

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 V - Maximum safe collector-emitter voltage before breakdown; defines upper rail limit in switch-mode circuits.
I_C (DC)	5 A - Continuous collector current rating; determines maximum steady-state load drive capability.
V_CE(sat)	0.1–0.3 V @ I_C = 2 A, I_B = 0.2 A - Low saturation voltage minimizes conduction loss and self-heating in saturated-switch operation.
h_FE2 (Y-grade)	160–320 @ V_CE = 1 V, I_C = 2 A - Confirmed DC current gain range used for base drive sizing in linear amplifiers or switch drivers.
P_C (T_A)	1.3 W @ T_A = 25 °C - Ambient-referenced power dissipation limit; requires heatsinking above ~50 °C ambient.
T_J	150 °C - Maximum junction temperature; sets thermal design margin for reliability under sustained load.

Pinout & Package

Package: TO-126-3LD (Case 340AS), surface-mountable through-hole package with integral metal tab for mechanical mounting and thermal conduction to heatsink. Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit node for majority carriers	Connected to ground or low-side return path; electrically and thermally tied to PCB copper pour or heatsink via mounting hole.
2 (Collector)	Current entry node under forward active/saturation	Connected to load supply rail; tab is internally connected to collector - requires electrical isolation if heatsink is grounded.
3 (Base)	Control terminal for minority carrier injection	Driven by current-limited source (e.g., microcontroller GPIO + series resistor); base-emitter saturation voltage is 0.9–1.2 V at I_C = 2 A.

Key Features

Feature	Design Value
Low V_CE(sat)	0.1–0.3 V enables <1 W conduction loss at 2 A, reducing thermal stress in compact motor driver PCBs.
High h_FE Y-grade	160–320 at 2 A supports reduced base drive current (e.g., 6–12 mA typical), easing MCU GPIO sourcing requirements.
Complementary pairing	Explicitly designed as NPN complement to KSB1151 PNP, enabling matched push-pull output stages without gain mismatch.
Pulse current capability	8 A peak (PW ≤ 10 ms, duty ≤ 50%) allows short-term overload handling in solenoid or lamp inrush control.

Applications

DC Motor Driver	Relay Driver
Use Scenario: Driving 12 V/3 A brushed DC motors in industrial actuators with PWM-controlled speed regulation. IC Role / Device Role / Timing Role: NPN power switch operating in saturation mode to connect motor winding to ground. Use Value: Low V_CE(sat) limits I²R loss to <0.6 W at full load, permitting use without forced air cooling in sealed enclosures.	Use Scenario: Controlling 24 V/2 A electromagnetic relays in PLC I/O modules with microcontroller GPIO interface. IC Role / Device Role / Timing Role: High-current interface transistor providing galvanic isolation between logic-level controller and coil circuit. Use Value: Verified 5 A DC rating and 8 A pulse capability ensure reliable coil energization even during cold-start voltage dips.
Linear Regulator Pass Element	Power Supply OR-ing Diode Replacement
Use Scenario: Serving as pass transistor in adjustable 5–15 V, 3 A linear regulators for analog sensor signal conditioning. IC Role / Device Role / Timing Role: Linear-mode current amplifier regulating output voltage via feedback-controlled base bias. Use Value: Stable h_FE across 0.1–5 A range enables predictable loop gain and thermal foldback response.	Use Scenario: Replacing Schottky diodes in redundant 12 V power supply OR-ing circuits to reduce forward drop and heat generation. IC Role / Device Role / Timing Role: Active NPN switch configured in emitter-follower topology to emulate ideal diode behavior. Use Value: V_CE(sat) of 0.1–0.3 V cuts conduction loss by >70% vs. 0.4 V Schottky, improving efficiency in dual-rail backup systems.

DC Motor Driver

Relay Driver

Use Scenario: Driving 12 V/3 A brushed DC motors in industrial actuators with PWM-controlled speed regulation.

IC Role / Device Role / Timing Role: NPN power switch operating in saturation mode to connect motor winding to ground.

Use Value: Low V_CE(sat) limits I²R loss to <0.6 W at full load, permitting use without forced air cooling in sealed enclosures.

Use Scenario: Controlling 24 V/2 A electromagnetic relays in PLC I/O modules with microcontroller GPIO interface.

IC Role / Device Role / Timing Role: High-current interface transistor providing galvanic isolation between logic-level controller and coil circuit.

Use Value: Verified 5 A DC rating and 8 A pulse capability ensure reliable coil energization even during cold-start voltage dips.

Linear Regulator Pass Element

Power Supply OR-ing Diode Replacement

Use Scenario: Serving as pass transistor in adjustable 5–15 V, 3 A linear regulators for analog sensor signal conditioning.

IC Role / Device Role / Timing Role: Linear-mode current amplifier regulating output voltage via feedback-controlled base bias.

Use Value: Stable h_FE across 0.1–5 A range enables predictable loop gain and thermal foldback response.

Use Scenario: Replacing Schottky diodes in redundant 12 V power supply OR-ing circuits to reduce forward drop and heat generation.

IC Role / Device Role / Timing Role: Active NPN switch configured in emitter-follower topology to emulate ideal diode behavior.

Use Value: V_CE(sat) of 0.1–0.3 V cuts conduction loss by >70% vs. 0.4 V Schottky, improving efficiency in dual-rail backup systems.

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	V_CEO = 100 V, I_C = 8 A, TO-252 package; higher voltage rating but larger footprint and no h_FE grade marking.	Better suited for 48 V industrial bus interfaces; less optimal for space-constrained 12–24 V relay drivers due to DPAK thermal interface.	Select when higher V_CEO margin or higher pulse current is required; verify PCB pad layout compatibility.
2SD1762	V_CEO = 60 V, I_C = 3 A, TO-220 package; lower I_C rating and ungraded h_FE (min 60), but widely available and cost-optimized.	Appropriate for lower-current (<2 A) loads; lacks Y-grade consistency for precision biasing in analog regulators.	Choose for cost-sensitive, non-critical switching where 3 A rating suffices and h_FE variation is acceptable.

Compared with MJD122G and 2SD1762, the KSD1691YSTSTU offers tighter h_FE grading (Y), lower V_CE(sat), and TO-126's compact through-hole form factor - making it preferable for space-limited, thermally constrained 5 A switching applications requiring predictable gain and minimal conduction loss.

Availability

KSD1691YSTSTU is available at Aetrix Electronics and suitable for DC motor drivers, relay drivers, and linear regulator pass elements requiring stable component supply and consistent h_FE grading.

Supply support for KSD1691YSTSTU 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 is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The KSD1691YSTSTU belongs to onsemi's general-purpose bipolar power transistor product line, engineered for robust, cost-effective switching and linear amplification in industrial controls and power management subsystems.

FAQ

What is the h_FE grade of KSD1691YSTSTU and how is it marked?

The KSD1691YSTSTU carries the "Y" h_FE grade, indicating a DC current gain range of 160–320 at V_CE = 1 V and I_C = 2 A. This grade is laser-marked on the device body as part of the "D1691" code followed by "Y", per the onsemi datasheet marking diagram and h_FE classification table.

Is KSD1691YSTSTU pin-compatible with other TO-126 NPN transistors like KSD1691YS?

Yes, KSD1691YSTSTU shares identical TO-126-3LD pinout (Emitter–Collector–Base) and mechanical dimensions with KSD1691YS and KSD1691GSTU. All variants use Case 340AS outline and have matching terminal assignments, enabling direct substitution where h_FE grade and Pb-free compliance meet design requirements.

What is the maximum allowable case temperature for continuous operation of KSD1691YSTSTU?

The KSD1691YSTSTU has a maximum junction temperature of 150 °C and a case power dissipation limit of 20 W at T_C = 25 °C. Derating begins linearly above 25 °C - consult Figure 7 in the onsemi datasheet to determine safe operating power at elevated case temperatures, e.g., ~12 W at T_C = 75 °C.

Does KSD1691YSTSTU require a heatsink in 5 A DC operation?

Yes, sustained 5 A DC operation exceeds the 1.3 W ambient-rated power dissipation. Even with low V_CE(sat), power loss reaches ~1.5 W at worst-case 0.3 V saturation, necessitating a heatsink to maintain T_J ≤ 150 °C. Thermal design must account for junction-to-case (R_θJC) and case-to-ambient (R_θCA) resistance per the datasheet's derating curves.

How does KSD1691YSTSTU compare to its complementary PNP counterpart KSB1151?

KSD1691YSTSTU and KSB1151 share matched voltage ratings (60 V), similar current capabilities, and complementary polarity - enabling balanced push-pull output stages. The KSD1691YSTSTU's Y-grade h_FE ensures predictable NPN gain, while KSB1151 provides corresponding PNP characteristics for symmetrical drive in H-bridge or Class AB amplifier designs.

KSD1691YSTSTU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 5 A

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 300mV @ 200mA, 2A

Current - Collector Cutoff (Max):: 10µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 160 @ 2A, 1V

Power - Max:: 1.3 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126-3

KSD1691YSTSTU FAQ

1.How can I place an order for KSD1691YSTSTU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSD1691YSTSTU 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 KSD1691YSTSTU reliable?

The price and inventory of KSD1691YSTSTU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSD1691YSTSTU is usually 5 days.

3.What payment methods are accepted for KSD1691YSTSTU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSD1691YSTSTU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSD1691YSTSTU?

KSD1691YSTSTU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSD1691YSTSTU 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 KSD1691YSTSTU?

For technical support, including KSD1691YSTSTU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSD1691YSTSTU requirements.

6.How does Aetrix verify that KSD1691YSTSTU is sourced from the original manufacturer or authorized distributors?

All KSD1691YSTSTU 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 KSD1691YSTSTU meets industry standards.

7.What is the process for return or replacement of KSD1691YSTSTU?

All KSD1691YSTSTU units undergo pre-shipment inspection (PSI). If there is an issue with KSD1691YSTSTU, 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 KSD1691YSTSTU part is unused and in its original packaging.

Return procedure for KSD1691YSTSTU:

1.Submit a request within 90 days.

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

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