NTC divider calculator

Calculate a thermistor divider’s voltage, sensitivity and self-heating power versus temperature.

Schematic

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Results

Sensor output voltage1.65 V

Divider voltage versus temperature

Output

Sensor resistance	10 kΩ
Temperature sensitivity	-36.66 mV/°C

Advanced results

Sensor current	165 µA
Sensor dissipation	272.25 µW

How ntc divider works

R1 pulls the output toward V1; TH1 pulls it toward ground. An NTC thermistor’s resistance falls as it warms, so the output falls too. R25 and Beta describe the thermistor at the fixed 25 °C reference.

R(T)=R_{25}e^{B(1/(T+273.15)-1/298.15)}

Beta-law approximation, unloaded output and fixed ambient temperature. Reported sensor power is electrical dissipation; temperature rise requires the thermistor’s dissipation constant and mounting conditions.

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Do the math

Selected input values
TH1 — Sensor temperature	25 °C
R1	10 kΩ
TH1 — Thermistor resistance at 25 °C	10 kΩ
TH1 — Thermistor beta constant	3950 K
V1	3.3 V

Thermistor resistance: $R(T)=R_{25}e^{B(1/(T+273.15)-1/298.15)}$
$10\,\mathrm{k\Omega}e^{3950(1/298.15-1/298.15)}$
≈ 10 kΩ
Output voltage: $V_O=V_1R(T)/(R_1+R(T))$
$3.3\,\mathrm{V}\times\frac{10\,\mathrm{k\Omega}}{20\,\mathrm{k\Omega}}$
≈ 1.65 V
Sensor dissipation: $P_T=V_O^2/R(T)$
$\frac{(1.65\,\mathrm{V})^2}{10\,\mathrm{k\Omega}}$
≈ 272.25 µW

NTC divider calculator

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Schematic

Results

How ntc divider works

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