NXP Semiconductors KTY81/222,112

Overview

KTY81/222,112 from NXP Semiconductors is a silicon-based positive temperature coefficient (PTC) temperature sensor in SOD70 plastic package, delivering 2000–2040 Ω resistance at 25 °C with ±1.27 K max temperature error and 0.79 %/K nominal temperature coefficient. It operates from −55 °C to +150 °C and supports continuous sensing current up to 10 mA at 25 °C, used in HVAC control loops, motor winding thermal monitoring, and industrial oven temperature feedback.

For engineers reviewing the KTY81/222,112 datasheet, KTY81/222,112 pinout, KTY81/222,112 application, or KTY81/222,112 equivalent, this page provides verified specifications, package geometry, real-world use scenarios, and validated alternative parts for thermal sensing design-in and BOM optimization.

Technical Context

The KTY81/222,112 functions as a two-terminal resistive transducer whose resistance increases linearly with ambient temperature across its full operating range. Its PTC behavior ensures fail-safe operation-rising resistance under overtemperature conditions enables direct integration with comparator-based protection circuits without external biasing.

It exhibits virtually linear R–T characteristics between −20 °C and +100 °C (±1.41 K to ±3.46 K error), with thermal time constants of 30 s in still air, 5 s in still liquid, and 3 s in flowing liquid-enabling rapid response in liquid-cooled systems while maintaining stability in air-sensed applications.

Key Specifications

Pinout & Package

The KTY81/222,112 is housed in a SOD70 plastic near-cylindrical single-ended package with two in-line leads. Lead spacing is 2.54 mm for bulk packaging and 5.08 mm for tape-and-reel (spread leads). Dimensions: 4.4–4.8 mm body width, 5.0–5.2 mm height, 3.6–4.2 mm thickness.

Key Features

Applications

Equivalent & Alternatives

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

Compared with KTY81/221 and TSI222, the KTY81/222,112 offers the highest baseline resistance in the KTY81/2 series (2000–2040 Ω), minimizing current-source loading errors in high-impedance signal chains while retaining identical long-term drift and thermal time constant performance.

Availability

KTY81/222,112 is available at Aetrix Electronics and suitable for HVAC control systems, motor thermal protection circuits, and industrial oven temperature regulation requiring stable component supply across multi-year production cycles.

Supply support for KTY81/222,112 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 designed by NXP as a family of rugged, low-cost silicon PTC sensors targeting cost-sensitive industrial temperature monitoring where long-term stability and fail-safe behavior outweigh ultra-high precision requirements.

FAQ

What is the maximum continuous operating current for KTY81/222,112 at 150 °C?

The maximum continuous sensor current for KTY81/222,112 is 2 mA at 150 °C, as specified in Table 5 (Limiting Values). Exceeding this value risks accelerated resistance drift and permanent calibration shift. At 25 °C, the rating increases to 10 mA, allowing higher signal-to-noise ratio in low-temperature applications. Always verify self-heating error using ∆T = I² × R × θ_JA in your PCB layout.

Does KTY81/222,112 require polarity-aware PCB layout?

No, KTY81/222,112 is a symmetric two-terminal device with identical electrical contacts on both pins (Table 2). Pin 1 and Pin 2 serve interchangeable roles as current entry/exit points-no orientation marking or directional silkscreen is needed. This simplifies automated placement and eliminates reverse-mount risk in SMT assembly.

How does the R₁₀₀/R₂₅ ratio of 1.676–1.716 impact system-level calibration?

The R₁₀₀/R₂₅ ratio of KTY81/222,112 defines the expected resistance change from 25 °C to 100 °C, enabling two-point calibration without full curve fitting. For example, measuring 2000 Ω at 25 °C and 3352–3432 Ω at 100 °C confirms sensor health and permits linear interpolation with <±2 K error across that span-reducing firmware complexity versus Steinhart-Hart thermistor models.

Can KTY81/222,112 be used in flowing liquid environments?

Yes, KTY81/222,112 has a thermal time constant of 3 seconds in flowing liquid (Table 6), making it suitable for coolant temperature monitoring in pumps, heat exchangers, and battery liquid cooling loops. Its SOD70 epoxy encapsulation provides IP67-equivalent moisture resistance when soldered with conformal coating, though direct submersion beyond 1 atm requires mechanical sealing per application requirements.

What is the meaning of the '112' suffix in KTY81/222,112?

The '112' suffix in KTY81/222,112 denotes the packaging variant: bulk packaging with 2.54 mm lead-to-lead distance (per Figure 4 and Section 8). It distinguishes this version from tape-and-reel variants (e.g., KTY81/222,114) which use 5.08 mm spread leads. The base type KTY81/222 remains unchanged-the '112' specifies mechanical handling format only.