Match the reference to the application.
The circuit specifies the required 50 kΩ NTC curve. Include source impedance, capacitance and sampling delay in the integration review.
Review the specification →GUILCOR · NTC thermistors
50 kΩ NTC
Give the input enough time to settle.
A 50 kΩ divider has a finite source impedance. Estimate its RC settling time before selecting a filter capacitor or sampling delay.
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Understand the reference
What defines a 50 kΩ NTC?
50 kΩNominal resistance at 25 °C
NegativeResistance decreases as temperature rises
Curve + packageBoth must match the application
An input can be electrically correct at steady state and still be sampled too early. Source resistance, capacitance and switching determine the transient response seen by the ADC.
A 50 kΩ NTC is a negative temperature coefficient thermistor with a nominal resistance of 50,000 Ω at 25 °C (R25). The value is a reference point, not a fixed resistance during use. Select the resistance–temperature characteristic together with tolerance, excitation and the completed probe construction.
SELECTION / YOUR APPLICATION
Is 50 kΩ NTC the right starting point?
Review 100 kΩ NTC alongside 50 kΩ NTC.
Compare the nominal resistance, reference temperature and full R/T characteristic. Matching at one temperature does not establish a compatible replacement over the operating interval.
Explore 100 kΩ NTC →Keep the complete specification together.
Keep the controller reference and the specified NTC curve together. Check tolerances, cable and probe construction rather than selecting by resistance or connector alone.
Prepare your enquiry →These links support a specification review. They do not establish interchangeable parts or availability of a complete assembly.
Application check
Check a simplified RC settling budget.
Tool input range: -20 to 100
Tool input range: 0.001 to 1000
Tool input range: 8 to 24
Tool input range: 0.001 to 1e+08
For a 50 kΩ pull-up, calculate the divider’s Thévenin resistance and a first-order RC time constant. Compare a chosen delay with the time needed to reach half an ideal ADC code after a full-scale step.
Source resistance
RC time constant
Time to half-LSB
Residual error after delay
Enable JavaScript to calculate.
This is a single-pole lumped model. A switched-capacitor ADC includes input-switch resistance, kickback and acquisition requirements that need its own datasheet or simulation. Do not treat this result as a universal ADC timing specification.
Model equationRth = RNTC ∥ Rs; τ = Rth C; t½LSB = (N + 1) ln(2) τ
Evaluate the largest source resistance over the application interval. Check the actual ADC acquisition circuit rather than relying solely on its DC input impedance.
Operating principle
Read the characteristic, not just R25.
Illustrative resistance values
| Temperature | Resistance |
|---|---|
| -20 °C | 526,923.45 Ω |
| 0 °C | 168,103.02 Ω |
| 25 °C | 50,000.00 Ω |
| 50 °C | 17,940.91 Ω |
| 85 °C | 5,433.35 Ω |
| 100 °C | 3,487.60 Ω |
From resistance to temperature
The constant-β approximation uses R(T) = R25 × exp[β(1/T − 1/298.15)], with absolute temperature in kelvin. It is useful for comparing circuit assumptions; a real part may need its specified R/T table or Steinhart–Hart coefficients for the required interval.
For Steinhart–Hart, 1/T = A + B ln(R) + C[ln(R)]³. Use coefficients and resistance units supplied for the selected part. A coefficient labelled B here is not automatically the same as a thermistor’s β value.
The temperatures in this example are calculation points, not an operating-temperature rating. Confirm the element, cable, seals and assembled probe limits.
A larger capacitor can attenuate fast disturbances while increasing settling time. It can also interact with the input driver and multiplexed sampling.
Selection checklist
Specify the complete sensing assembly.
Electrical and thermal requirements
- R25 tolerance and the exact R/T curve, β interval or coefficients.
- Required temperature interval and complete measurement error budget.
- Measuring current, allowable dissipation and self-heating under the actual mounting conditions.
- Response time with its stated medium, flow and test method; no universal response time follows from R25.
- Ageing, drift and environmental qualification documented for the selected part.
Mechanical and installation requirements
- Element or assembled probe dimensions, sheath and contact arrangement.
- Cable length, insulation, connector and total two-wire loop resistance.
- Sealing, media compatibility, pressure and ingress requirements where applicable.
- Controller curve support, supply, input range, loading and acquisition timing.
- Calibration points and required documentation for the final assembly.
Wiring and measurement
Connect the sensor and account for the circuit.
Example two-wire divider
Supply → fixed pull-up Rs → measurement node
Measurement node → NTC → ground
ADC measures the node relative to ground
For an unloaded input, Vout = Vs × RNTC / (Rs + RNTC). In this arrangement, warming an NTC lowers the output voltage. The element has no polarity, although an assembled cable or connector can have a specified pin assignment.
Separate electrical and thermal errors
Lead resistance, leakage, finite input impedance and sampling transients can alter the measured signal. Measuring current also dissipates power in the element: P = I²R. The approximate steady-state self-heating rise is P/δ when the dissipation factor δ applies to the actual installation.
A robust coating or sheath can improve environmental protection while changing heat transfer. Validate the completed probe in its intended medium instead of carrying over the bare element’s response figure.
Application contexts
Where to evaluate a 50 kΩ NTC.
Multiplexed data acquisition
Allow for the voltage step when switching from another channel.
Battery-powered sensors
Include settling time in the excitation pulse and energy budget.
Instrumentation
Coordinate the analog filter, input driver and conversion schedule.
Application examples are selection contexts. Suitability and any required certification depend on the identified reference and completed assembly.
Probe construction
Choose the installation format.
Match the sensing point, medium and mounting to the probe construction. These links explore construction families; confirm the required NTC characteristic when requesting a reference.
Frequently asked questions
50 kΩ NTC questions.
Is high DC input impedance enough to validate an ADC connection?
No. The input can draw transient charge during acquisition. Check its sampling structure, allowed source impedance and acquisition time.
Is every 50 kΩ NTC interchangeable?
No. Match R25, the complete curve and tolerances, then verify electrical excitation, construction, cable, environmental limits and controller configuration.
Can the example values replace a product datasheet?
No. The table and tool illustrate stated assumptions. Use the selected reference’s data, curve and test conditions for specification and validation.
What information should I send for a probe request?
Include the required R25 and curve, temperature range, allowable error, medium, mounting, dimensions, cable and connector, controller input and expected quantity.
Technical background: Manufacturer guidance on sensing and readout. Example calculations are educational models with the assumptions stated above.
GUILCOR / YOUR ENQUIRY
Define your 50 kΩ NTC enquiry.
Send the electrical reference and the installation details together. A nominal resistance alone does not define the right replacement or assembled probe.
Missing a reference or datasheet?
Send the component marking, equipment reference and any photographs or documents you have. These provide a starting point for identifying what must be confirmed.
The outline helps prepare your enquiry. Copying it does not send a request.
FOUR DETAILS THAT MOVE THE DISCUSSION FORWARD
01
Sensor and controller
Part number, nominal resistance and reference temperature, R/T data or specified β interval, tolerance and controller input.
02
Measurement conditions
Operating and peak temperatures, required accuracy and response target, measured medium and exposure to moisture or cleaning.
03
Assembly and connection
Probe dimensions, mounting or insertion, cable length and insulation, connector or lead termination. Attach a drawing or photo.
04
Project and validation
Sample and production quantities, target delivery, calibration or documentation needs, and the checks required before approval.