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 20KΩ 
 Temperature sensors 

Reliable NTC thermistor for temperature monitoring in electronic devices and automation applications.

 Maximum precision
+/- 0,20°K

 Minimum temperature
-50°C

 Maximum temperature
+150°C

 Minimum dimensions
2 x 10

Response time

Fast

 Drift

Low

 Self-warming
Low

Price
Low

What is a 20KΩ sensor ?Operating principleTechnical SpecificationsWiring ConfigurationSelf-warmingApplication areas

What is a 20KΩ sensor ?

The NTC 20 kΩ is a thermistor with a high nominal resistance (20,000 Ω at 25 °C), ideal for long-term measurement or low-power systems.

Due to its minimal current, it generates very little internal heat, ensuring excellent stability and accuracy over time.

It is a sensor often used in medical devices, embedded electronics, and climate monitoring systems.

Operating principle

The resistance follows the typical exponential law of NTC:

R(T) = R₂₅ × e^{β (1/T - 1/T₂₅)}

  • R₂₅ = 1000 Ω 
  • β ≈ 3500 – 3900 K (depending on manufacturer)
  • T in Kelvins

This resistance variation is measured by a microcontroller through a voltage divider and translated into temperature using the Steinhart–Hart equation.

Technical Specifications

Parameter
 Typical value

Nominal resistance (25 °C)

 20 000 Ω ±1 %
Constant β 3500–3900 K

Sensitive material

Metallic oxide (Mn, Ni, Co)

Type of case Epoxy / glass / ceramic

Maximum measurement current

0,1 mA

Response time

0.3 to 1 s

Operating temperature

−50 → +150 °C

Lifetime

100,000 thermal cycles

Wiring Configuration

The NTC 20 kΩ is used in voltage divider circuits in low-power analog or digital systems.

 +Vcc
   │
  [Rfixe]
   │────► AD (µC)
  [NTC 20kΩ]
   │
  GND

Self-warming

Thanks to its high impedance, self-heating is virtually negligible (<0.015 °C), an advantage for long-term measurements without drift.

Application areas

🧠 Medical and Biomedical Devices

⚙️ Precision Embedded Electronics (IoT, Drones, Autonomous Sensors)

🧱 Slow and Continuous HVAC Systems

🔋 Battery/PCB Thermal Monitoring

🌡️ Scientific Instrumentation and Climate Control


Should I choose a 20KΩ sensor ?

Strengths points

  • 🔋 Ideal for low power consumption systems
         → Its high resistance drastically reduces the measurement current, perfect for IoT, medical, or battery-powered devices.
  • 🎯 Exceptional stability over time
         → Very low drift (< ±0.05 K/year), ensuring reliability over several years without recalibration.
  • 🔥 Almost no self-heating
         → Less than 0.015 °C of error due to dissipation, allows for ultra-stable continuous measurements.
20kΩ sensors

Weaknesses points

  • 📉 Slightly lower responsiveness
    → Its strong resistance implies a slightly longer stabilization time than lower value NTCs.
  • 🧮 Digital conversion necessary
    → The non-linearity requires the use of a lookup table or the Steinhart–Hart formula to calculate the temperature.
  • 🌡️ Reduced accuracy at high temperature
    → As with most NTCs, the resistance drops beyond 100–120 °C.

Useful information

Here is some useful information regarding the 20KΩ sensors.

(NTC 20 kΩ at 25 °C, beta constant = 3950 K)

Temperature (°C) Resistance (Ω) Temperature (°C) Resistance (Ω)
−50 498 836 60 5 866
−40 315 802 70 4 411
−30 203 378 80 3 377
−20 134 164 90 2 604
−10 89 681 100 2 026
0 60 922 110 1 567
10 42 033 120 1 229
20 29 599 130 967
25 20 000 140 760
30 13 726 150 598
40 9 520 160 472
50 6 724 170 373

💡 Between −20 °C and +100 °C, the resistance is divided by approximately 65, following a classic exponential law for β ≈ 3950.

Class / Tolerance
 Tolerance at 25 °C (R25)
 Max error on T° (−40 → +125 °C)
 Typical usage
±1 % ±200 Ω ±0,2 K Applications scientifiques et médicales
±2 % ±400 Ω ±0,4 K Mesures de contrôle industriel
±3 % ±600 Ω ±0,6 K Systèmes embarqués
±5 % ±1 000 Ω ±1 K Dispositifs grand public
🔹 Glass-encapsulated sensors provide the best thermal stability, resistant up to +150 °C.

Complet formul:

1/T = A + B · ln(R) + C · [ln(R)]³

Typical coefficients for NTC 20 kΩ β = 3950 K:

  • A = 1.4051 × 10⁻³
  • B = 2.369 × 10⁻⁴
  • C = 1.019 × 10⁻⁷


🔹 Example 1: Temperature from R

R = 13,726 Ω

ln(13726) = 9,53

1/T = 1,4051e−3 + 2,369e−4 (9,53) + 1,019e−7 (9,53)³ = 3,05e−3

T = 1 / 3,05e−3 = 327,9 K = 54,8 °C

✅ Measured temperature: ≈ 55 °C


🔹 Example 2: Resistance from T

T = 80 °C = 353.15 K

R = R₂₅ · e^(β(1/T − 1/T₂₅))

R = 20000 · e^(3950 × (1/353,15 − 1/298,15)) = 3377 Ω

✅ Expected resistance: ≈ 3.38 kΩ

The NTC 20 kΩ is integrated into a voltage divider, used for analog reading on microcontrollers or low-power instrumentation.

🔹 Typical components

Component
 Function
NTC 20 kΩ Temperature sensor
R fixed (20 kΩ)
 Reference resistance
Microcontroller (ADC)
 Analog Lecture
Capacitor 100 nF
 Noise filtering
Power Supply 3.3 / 5 V
 Tension stable
🔹 Functional diagram (ASCII)
  +3.3V / +5V
       │
     [Rfixe]
       │────► ADC (microcontroller input)
     [NTC 20kΩ]
       │
      GND
💡 Its high resistance allows for stable accuracy with minimal measurement current, perfect for autonomous and sustainable applications.

 We integrate any sensor into any probe 

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 Smooth tube 

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PCBA design

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Winding

More than 1,000,000 probes delivered in 2025

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