for HP 42S
NTC10K - NTC Thermistor Resistance Approximation Formula of three coefficients for Murata's 10kΩ NTC thermistors - Rev.2.3 for HP 42s

Usage

Resistance → Temperature conversion : [SOLVER] [XV10K|XH10K] Resistance [R] [Temp]
Temperature → Resistance conversion : [SOLVER] [XV10K|XH10K] Temperature [Temp] [R]

Variables

MEM "R"   : resistance [&Omega];
MEM "Tc" : temperature [°C]

Resistance Approximation Formula for NTC Thermistors

R_T = R_{25} \exp\left\{ B \left( \displaystyle\frac{1}{ 298.15 + (T - T_{25}) + C (T - T_{25})^2 + D (T - T_{25})^3} - \frac{1}{273.15 + T_{25}}\right)\right\} … (1)
where,
RT : Resistance at T [Ω]
R25 : Nominal Resistance at T25 [Ω]
T25 : Nominal Temperature (25 °C)
T : Temperature [°C]

Table.1 Approximation coefficients for some NTC thermistors


Part numberBCDRerr[%]Tmin [°C]Tmax [°C]Note



NTSA0XV103E3878.12.79999e-42.77985e-07±0.135472-40125Discontinued 2016 


NCP21XV103J3866.373.74252e-4-6.2382e-07±0.185954-40125 


NCP15XH103D3332.315.55745e-44.74033e-07±0.182184-40125Applicable upto 139 °C

The component-dependent coefficients B, C, and D in the three-coefficient approximation formula (1) were determined using a computer program to minimize the absolute error within the specified temperature range relative to the median value of each component.

Approximation errors

NTC Thermistor approximation vs. Temperature
Fig.1 Approximation error V.S. Temperature, Resistance V.S. Temperature
(DUT: NCP21XV103J, NCP15XH103D and NCU18HX103DS)

Program list

NTC10K — NTC thermistor approximate function for NTSA0XV103, NCP21XV103 and NCP15XH103, Rev.2.30 (March 18, 2025)
NTSA0XV103 NCP21XV103 NCP15XH103 
01 LBL "A0XV"
02 MVAR "Tc" 
03 MVAR "R"
04 RCL "Tc"
05 25
06 -
07 ENTER
08 ENTER
09 ENTER
10 2.77985E-7
11 ×
12 2.79999E-4
13 +
14 × 
15 1 
16 +
17 ×
18 298.15
19 +
20 1/χ
21 298.15
22 1/χ
23 -
24 3878.1
25 ×
26 E↑χ
27 1E4
28 ×
29 RCL- "R"
30 .END.

01 LBL "P1XV"
02 MVAR "Tc" 
03 MVAR "R"
04 RCL "Tc"
05 25
06 -
07 ENTER
08 ENTER
09 ENTER
10 -6.2382E-7
11 ×
12 3.74252E-4
13 +
14 × 
15 1 
16 +
17 ×
18 298.15
19 +
20 1/χ
21 298.15
22 1/χ
23 -
24 3866.37
25 ×
26 E↑χ
27 1E4
28 ×
29 RCL- "R"
30 .END.

01 LBL "P5XH"
02 MVAR "Tc" 
03 MVAR "R"
04 RCL "Tc"
05 25
06 -
07 ENTER
08 ENTER
09 ENTER
10 4.74033E-7
11 ×
12 5.55745E-4
13 +
14 × 
15 1 
16 +
17 ×
18 298.15
19 +
20 1/χ
21 298.15
22 1/χ
23 -
24 3332.31
25 ×
26 E↑χ
27 1E4
28 ×
29 RCL- "R"
30 .END.
Download 'A0XV' / 'P1XV' / 'P5XH' - raw program files for the Free42

SEE ALSO

APPENDIX

Program library for the HP 42S
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