What are NTC thermistors

NTC stands for Negative Temperature Coefficient. An NTC thermistor is a resistor that falls in resistance when the temperature rises. This property makes it useful as a temperature sensor and as a part of circuits that must react to temperature changes. NTC thermistors are compact and low cost and are often found in consumer devices and industrial equipment.

Common part values and why they matter

Thermistors are commonly available in standard nominal resistance values measured at 25 degrees Celsius. Two popular values are the 10k thermistor and the 100k thermistors. The nominal value affects how the sensor sits in a measurement circuit and how sensitive it feels to temperature changes.

How to read a thermistor in a circuit

Most hobby and many industrial circuits use a simple voltage divider to read the thermistor with an analog input. The thermistor is placed in one leg and a fixed resistor in the other. By measuring the divider voltage the controller can calculate the temperature using the thermistor curve or a lookup table.

1. Choose a reference resistor close to the nominal thermistor value for best linearity near your target temperature.
2. Use the device table or the Beta coefficient to convert resistance to temperature.
3. Apply a small excitation current to avoid self heating of the thermistor.

For detailed specifications and part options see the product page for 100k thermistors and 10k thermistor.

How to choose between 10k and 100k thermistors

Choice depends on these factors

• Input impedance If your ADC input is high impedance a 100k thermistor can be fine. For lower impedance inputs 10k often gives better noise immunity.
• Power consumption Higher resistance values reduce current draw which is helpful for battery powered designs.
• Temperature resolution Both values can offer good resolution but the exact curve and Beta value determine sensitivity in your target range.
• Interference Lower resistance parts like 10k can be less affected by stray noise in electrically noisy environments.

Review part data and match with your circuit needs. You can compare ranges and packaging on the detailed product listing for 10k thermistor and 100k thermistors.

Mounting and placement tips

How you place the thermistor affects reading accuracy

• Place the sensor where it actually measures the temperature of interest not where it is heated by nearby parts.
• Use thermal paste or proper contact for good thermal coupling when measuring metal surfaces.
• Protect the thermistor from moisture and corrosion if it will be used outdoors or in humid conditions.

Small bead style parts are fast to respond but need good protection. Larger epoxy coated parts are easier to handle in assembly and offer mechanical strength.

Calibration and accuracy

Thermistors are nonlinear devices. For higher accuracy you can do a two point calibration or use a small lookup table in the microcontroller. Many designs use a table that covers the expected temperature span with linear interpolation between points. For precise work consider the tolerance class in the part data sheet.

Where NTC thermistors are used

Common uses include

• Consumer thermostats and kitchen appliances
• Battery management and charging circuits
• Environmental monitoring and HVAC controls
• Over temperature protection for power supplies

Both 10k thermistor and 100k thermistors appear across these areas depending on the design goals.

Where to see parts and specifications

For a clear list of available types packaging options and detailed curves visit the product page. The supplier shows part curves tolerance and mounting options to help you choose the right device. See the technical pages for full details on 100k thermistors and the page for 10k thermistor.