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Home > Products > Sensors, Transducers > Temperature Sensors > PTC Thermistors

NXP Semiconductors KTY81/250,112

Name: KTY81/250,112
Brand: NXP Semiconductors
SKU: KTY81/250,112
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KTY81/250,112

Manufacturer:: NXP Semiconductors

Category:: PTC Thermistors

Package:: TO-226-2, TO-92-2 (TO-226AC)

Datasheet:: KTY81/250,112.pdf

Description:: SENSOR PTC 2KOHM PBCYT2

Quantity:: RFQ Add To RFQ list

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Inventory:2,624

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Product details

Overview

KTY81/250,112 from NXP Semiconductors is a silicon-based positive temperature coefficient (PTC) temperature sensor in SOD70 plastic package, designed for precision analog temperature measurement in industrial control and automotive thermal monitoring systems. It delivers 1900–2100 Ω resistance at 25 °C, 0.79 %/K temperature coefficient, ±6.35 K max error at 25 °C, and operates from −55 °C to +150 °C.

For engineers reviewing the KTY81/250,112 datasheet, KTY81/250,112 pinout, KTY81/250,112 application, or KTY81/250,112 equivalent, this page provides verified specifications, validated SOD70 package details, real-world use scenarios in HVAC and motor protection, and two confirmed alternative parts with documented parameter differences.

Technical Context

The KTY81/250,112 uses monocrystalline silicon resistive sensing element with inherently linear PTC behavior over −55 °C to +150 °C, enabling direct resistance-to-temperature conversion without complex linearization circuitry. Its fail-safe positive coefficient ensures rising resistance with rising temperature-critical for overtemperature shutdown detection.

Thermal time constant is 30 s in still air, 5 s in still liquid, and 3 s in flowing liquid-making it suitable for both slow ambient monitoring and faster fluid temperature tracking. Maximum continuous sensor current is 10 mA at 25 °C, derating to 2 mA at 150 °C per IEC 60134 limiting values.

Key Specifications

Parameter	Value and Actual Design Meaning
R₂₅	1900–2100 Ω at 25 °C; defines baseline calibration point for resistance-temperature lookup tables
Temperature Coefficient	0.79 %/K typical; enables predictable, monotonic resistance increase per degree Celsius
R₁₀₀/R₂₅	1.676–1.716; quantifies resistance ratio between 100 °C and 25 °C for accuracy validation
Operating Range	−55 °C to +150 °C; supports under-hood automotive, industrial furnace, and power supply thermal management
Max Continuous Current	10 mA at 25 °C; sets upper limit for excitation current to avoid self-heating errors
Thermal Time Constant	3 s in flowing liquid; determines minimum response time for closed-loop coolant temperature control
Resistance Drift	≤3.2 Ω after 10,000 h at 150 °C; guarantees long-term stability in high-temperature embedded applications

Pinout & Package

The KTY81/250,112 is housed in the SOD70 near-cylindrical plastic package with two in-line leads, 2.54 mm lead-to-lead spacing in bulk packaging, and 5.08 mm spacing for tape-and-reel variants. Dimensions: 4.4–4.8 mm width × 5.0–5.2 mm height × 3.6–4.2 mm thickness.

Pin/Terminal	Circuit Role	Design Meaning
1	Electrical contact	Unpolarized resistive terminal; interchangeable with Pin 2 in 2-terminal configuration
2	Electrical contact	Unpolarized resistive terminal; forms complete sensor element with Pin 1

Key Features

Feature	Design Value
Positive Temperature Coefficient	Fail-safe behavior: resistance increases with temperature-enables direct overtemp detection without active circuitry
Virtually Linear Characteristics	±6.35 K max error at 25 °C and <±15 K across full range-reduces need for multi-point calibration
Long-Term Stability	≤3.2 Ω resistance drift after 10,000 h at 150 °C-ensures calibration integrity in sealed industrial enclosures
ESD Sensitivity	Requires handling per IEC 61000-4-2 Level 2; mandates ESD-safe assembly for automotive production lines

Applications

Motor Winding Protection	HVAC Ambient Sensing
Use Scenario: Embedded inside stator windings of industrial AC motors to detect thermal overload before insulation failure. IC Role / Device Role / Timing Role: Passive resistive temperature sensor providing analog R-T feedback to motor controller ADC input. Use Value: 0.79 %/K coefficient enables reliable trip-point detection at 130 °C with ≤3.2 Ω long-term drift-eliminates need for periodic recalibration.	Use Scenario: Mounted on HVAC control board to monitor room air temperature for PID fan speed regulation. IC Role / Device Role / Timing Role: Analog temperature transducer interfaced via simple voltage divider to microcontroller ADC. Use Value: ±6.35 K error at 25 °C and 30 s thermal time constant in air ensure stable setpoint tracking without overshoot in residential thermostats.
Automotive Coolant Monitoring	Power Supply Thermal Shutdown
Use Scenario: Immersed in engine coolant loop to provide real-time temperature data for ECU fuel mapping and fan control. IC Role / Device Role / Timing Role: Two-terminal PTC resistor placed in series with excitation current source for ratiometric measurement. Use Value: 3 s thermal time constant in flowing liquid matches coolant dynamics; 150 °C rating exceeds peak operating temperatures in turbocharged engines.	Use Scenario: Mounted on heatsink of DC-DC converter to trigger shutdown if MOSFET junction temperature exceeds safe limit. IC Role / Device Role / Timing Role: Fail-safe thermal sentinel-rising resistance directly reduces bias current to enable comparator trip. Use Value: Positive coefficient ensures monotonic response; 1900–2100 Ω R₂₅ allows precise threshold setting with standard 1% resistors in comparator reference network.

Motor Winding Protection

HVAC Ambient Sensing

Use Scenario: Embedded inside stator windings of industrial AC motors to detect thermal overload before insulation failure.

IC Role / Device Role / Timing Role: Passive resistive temperature sensor providing analog R-T feedback to motor controller ADC input.

Use Value: 0.79 %/K coefficient enables reliable trip-point detection at 130 °C with ≤3.2 Ω long-term drift-eliminates need for periodic recalibration.

Use Scenario: Mounted on HVAC control board to monitor room air temperature for PID fan speed regulation.

IC Role / Device Role / Timing Role: Analog temperature transducer interfaced via simple voltage divider to microcontroller ADC.

Use Value: ±6.35 K error at 25 °C and 30 s thermal time constant in air ensure stable setpoint tracking without overshoot in residential thermostats.

Automotive Coolant Monitoring

Power Supply Thermal Shutdown

Use Scenario: Immersed in engine coolant loop to provide real-time temperature data for ECU fuel mapping and fan control.

IC Role / Device Role / Timing Role: Two-terminal PTC resistor placed in series with excitation current source for ratiometric measurement.

Use Value: 3 s thermal time constant in flowing liquid matches coolant dynamics; 150 °C rating exceeds peak operating temperatures in turbocharged engines.

Use Scenario: Mounted on heatsink of DC-DC converter to trigger shutdown if MOSFET junction temperature exceeds safe limit.

IC Role / Device Role / Timing Role: Fail-safe thermal sentinel-rising resistance directly reduces bias current to enable comparator trip.

Use Value: Positive coefficient ensures monotonic response; 1900–2100 Ω R₂₅ allows precise threshold setting with standard 1% resistors in comparator reference network.

Equivalent & Alternatives

The following parts are listed as comparable options for similar temperature sensing applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TSIC506-250	Digital output (I²C), 0.5 K accuracy, 3.3 V supply required; no analog interface needed	Replaces analog signal chain with digital bus-requires firmware I²C support and removes ADC dependency	Select when system already uses I²C sensors and board space permits SOIC-8 footprint
KTY83-110	Same SOD70 package but R₂₅ = 950–1050 Ω; lower base resistance, identical PTC curve shape	Suitable for lower-temperature ranges (<100 °C); requires recalibration of voltage-divider scaling	Select for cost-sensitive consumer appliances where 0–85 °C range suffices and existing PCB layout accommodates same footprint

Compared with TSIC506-250, the KTY81/250,112 avoids digital overhead and supply rail dependencies; compared with KTY83-110, it provides higher base resistance for improved noise immunity in long-wire industrial installations.

Availability

KTY81/250,112 is available at Aetrix Electronics and suitable for motor protection, HVAC control, automotive coolant monitoring, and power supply thermal shutdown requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for KTY81/250,112 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT markets.

The KTY81 series was developed by NXP specifically for high-reliability analog temperature sensing in harsh environments-emphasizing long-term stability, ESD robustness, and fail-safe PTC behavior for safety-critical thermal monitoring.

FAQ

What is the nominal resistance of KTY81/250,112 at 25 °C?

The KTY81/250,112 has a nominal resistance range of 1900 Ω to 2100 Ω at 25 °C, measured with 1 mA continuous excitation current. This value serves as the primary calibration anchor for resistance-to-temperature conversion in analog front-end designs using the KTY81/250,112.

Does KTY81/250,112 require polarity-aware connection?

No, the KTY81/250,112 is a two-terminal passive resistor with no polarity. Pins 1 and 2 are electrically identical and interchangeable in circuit design-no orientation sensitivity exists during PCB placement or wiring of the KTY81/250,112.

What is the maximum ambient temperature rating for KTY81/250,112?

The KTY81/250,112 is rated for continuous operation from −55 °C to +150 °C ambient temperature per IEC 60134 limiting values. At 150 °C, its maximum continuous sensor current must be limited to 2 mA to prevent thermal runaway or accelerated aging-verified in the KTY81/250,112 datasheet Section 5.

How does the thermal time constant of KTY81/250,112 affect system response?

The KTY81/250,112 exhibits a thermal time constant of 30 s in still air, 5 s in still liquid, and 3 s in flowing liquid. This defines how rapidly the KTY81/250,112 tracks ambient temperature changes-critical for selecting appropriate sampling intervals in closed-loop thermal control systems.

Is KTY81/250,112 compatible with standard SOD70 footprint layouts?

Yes, the KTY81/250,112 uses the standardized SOD70 package with 4.4–4.8 mm body width, 5.0–5.2 mm height, and 2.54 mm lead spacing in bulk form. It fits all PCB footprints designed for SOD70 components, including those used for KTY81/210, KTY81/220, and other members of the KTY81 family.

KTY81/250,112 Specifications

Product attributes: Attribute value

Manufacturer:: NXP Semiconductors

Series:: KTY81

Package/Case:: TO-226-2, TO-92-2 (TO-226AC)

Packaging:: Bulk

Product Status:: Obsolete

Resistance @ 25°C:: 2 kOhms

Resistance Tolerance:: -

Operating Temperature:: -55°C ~ 150°C

Power - Max:: -

Mounting Type:: Through Hole

Grade:: -

Qualification:: -

Supplier Device Package:: PBCYT2

KTY81/250,112 FAQ

1.How can I place an order for KTY81/250,112 through Aetrix?

Please submit a Request for Quotation (RFQ) for KTY81/250,112 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 KTY81/250,112 reliable?

The price and inventory of KTY81/250,112 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KTY81/250,112 is usually 5 days.

3.What payment methods are accepted for KTY81/250,112?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KTY81/250,112 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KTY81/250,112?

KTY81/250,112 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KTY81/250,112 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 KTY81/250,112?

For technical support, including KTY81/250,112 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KTY81/250,112 requirements.

6.How does Aetrix verify that KTY81/250,112 is sourced from the original manufacturer or authorized distributors?

All KTY81/250,112 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 KTY81/250,112 meets industry standards.

7.What is the process for return or replacement of KTY81/250,112?

All KTY81/250,112 units undergo pre-shipment inspection (PSI). If there is an issue with KTY81/250,112, 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 KTY81/250,112 part is unused and in its original packaging.

Return procedure for KTY81/250,112:

1.Submit a request within 90 days.

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

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