NXP Semiconductors KTY81/110,112

Overview

KTY81/110,112 from NXP Semiconductors is a silicon-based analog temperature sensor with positive temperature coefficient (PTC) resistance behavior, designed for precision measurement and closed-loop control in industrial and automotive thermal monitoring systems. It delivers R₂₅ = 990–1010 Ω at 25 °C, ±1.27 K max temperature error over −55 to +150 °C, and 0.79 %/K nominal temperature coefficient.

For engineers reviewing the KTY81/110,112 datasheet, KTY81/110,112 pinout, KTY81/110,112 application, or KTY81/110,112 equivalent, this page provides verified package mapping, resistance-vs-temperature tables, thermal time constant data (3 s in flowing liquid), continuous current limits (2 mA @ 150 °C), and validated alternatives for thermal sensing circuit design.

Technical Context

The KTY81/110,112 operates as a two-terminal passive resistive element whose resistance increases linearly with ambient temperature-enabling direct voltage-divider interfacing with ADCs or op-amp conditioning circuits. Its PTC behavior ensures fail-safe operation: rising resistance under overtemperature conditions reduces self-heating and prevents runaway failure modes.

It exhibits virtually linear R–T characteristics across −55 °C to +150 °C, with R₁₀₀/R₂₅ = 1.676–1.716 and R₋₅₅/R₂₅ = 0.480–0.500. Thermal time constants are specified as 3 s (flowing liquid), 5 s (still liquid), and 30 s (still air), defining dynamic response suitability for real-time thermal feedback loops.

Key Specifications

Pinout & Package

Encapsulated in the SOD70 plastic near-cylindrical single-ended package with 2 in-line leads, the KTY81/110,112 has no polarity or orientation dependency. The device is mechanically symmetric and electrically bidirectional.

Key Features

Applications

Equivalent & Alternatives

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

Compared with KTY81/110,112, TSI301-100 offers tighter R₂₅ tolerance but demands redesign for SMT integration, while KTY83-110 trades speed and precision for mechanical robustness and legacy compatibility-making KTY81/110,112 optimal for new designs requiring balance of accuracy, speed, and through-hole manufacturability.

Availability

KTY81/110,112 is available at Aetrix Electronics and suitable for motor protection, automotive climate control, industrial oven profiling, and power supply thermal foldback requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for KTY81/110,112 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 applications.

The KTY81 series was developed by NXP to deliver high-stability, linear PTC silicon temperature sensors for cost-sensitive yet reliability-critical thermal monitoring in harsh environments-replacing thermistors where long-term drift and linearity are design constraints.

FAQ

What is the recommended operating current for KTY81/110,112 to minimize self-heating error?

The KTY81/110,112 datasheet specifies Isen(cont) = 1 mA as the recommended operating current for temperatures above 100 °C to keep temperature error low. At this current, self-heating remains below 0.1 K in still air, preserving measurement accuracy. Exceeding 2 mA at 150 °C violates limiting values and risks long-term drift. Always verify bias network power dissipation using R₂₅ = 990–1010 Ω when designing the voltage divider for KTY81/110,112.

Does KTY81/110,112 have polarity or directional mounting requirements?

No, KTY81/110,112 is a two-terminal passive resistive device with no polarity. Pins 1 and 2 are electrically identical and interchangeable-mounting orientation does not affect function. The SOD70 package is mechanically symmetric, and the sensor operates identically regardless of current direction. This simplifies PCB layout and eliminates risk of reverse installation during assembly of KTY81/110,112.

How does the temperature coefficient of KTY81/110,112 vary across its operating range?

The temperature coefficient of KTY81/110,112 decreases with rising temperature: it is 0.79 %/K at 25 °C, 0.63 %/K at 100 °C, and 0.35 %/K at 150 °C. This non-constant TC is documented in Table 7 of the datasheet and results in a slightly sub-linear R–T curve. For high-accuracy applications above 100 °C, interpolation using the published resistance tables-not a fixed TC-is required to achieve ±1.27 K error bounds for KTY81/110,112.

Can KTY81/110,112 be used in liquid immersion environments?

Yes, KTY81/110,112 is qualified for use in liquid immersion, with thermal time constant specified as 5 s in still liquid and 3 s in flowing liquid. Its SOD70 plastic encapsulation provides moisture resistance suitable for coolant, oil, and non-corrosive aqueous media. However, prolonged exposure to aggressive solvents or high-pressure steam is not supported. All resistance and error specifications in the datasheet-including R₂₅ = 990–1010 Ω-are defined under liquid-immersion test conditions for KTY81/110,112.

What is the maximum allowable continuous current for KTY81/110,112 at 125 °C ambient?

At Tamb = 125 °C, the maximum continuous sensor current for KTY81/110,112 is 3.5 mA, interpolated from the limiting values table (2 mA at 150 °C; 10 mA at 25 °C). Operation above this value risks accelerated resistance drift and violates the Absolute Maximum Rating System per IEC 60134. For reliable 125 °C operation, maintain Isen(cont) ≤ 3.5 mA and confirm power dissipation stays below 3.5 mW using worst-case R₂₅ = 1010 Ω when designing the interface for KTY81/110,112.