SimSurfing
NTC Thermistor
Performance Simulator
Operation Manual

August, 2023
Murata ManufacturingCo., Ltd.
23 August 2023
Copyright © Murata Manufacturing Co., Ltd. All rights reserved. 2019

Contents
page
1. About This Tool
1-1. Outline
1-2. Main Functions

34

2. Quick Operation Guide
2-1. Simulation Graph Display
2-2. Overwriting Graphs
2-3. Comparison and Output of Simulation

56
7

3. Details of Operation
3-1. Selecting the Desired Type of NTC Thermistor
3-2. Selecting a Simulation Circuit
3-3. Changing/Setting the Simulation Conditions
3-4. Saving a Text File
3-5. Printing
3-6. Making a Mark on a Graph

8
9
10
17
18
19

4. About Circuit Patterns

22

5. Software Use Examples
5-1. circuit that achieves your desired output
28
5-2. Circuit Design That Maximizes Output Voltage Gain Through Arbitrary
Temperature
33
6. Version Confirmation and Contact Method
Appendix Preferred Numbers

38
39
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1. About This Tool
1-1. Outline
The SimSurfing NTC Thermistor Performance Simulator (hereafter called “this software”) is software
for simulating the output voltage versus temperature characteristics.
Each graph of the output voltage characteristics of the specified circuit, the output voltage error andthe temperature error are displayed.

3
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1. About This Tool
1-2. Main Functions (1/2)⚫ Regarding the grounding circuit of the NTC thermistor and that of the resistor, the output voltage
characteristics can be simulated.
<Example of circuit>⚫ In the default simulation, [Output Voltage (output voltage)], [Voltage Error (output voltage error)] and[Temperature Error (temperature conversion error)] are displayed as graphs.
⚫ In addition to the above 3 graphs, the following graphs can also be displayed.
• Vout Gain (output voltage per unit temperature)• Self Heating (self-heating)• Output Voltage Approximation (approximate value of the output voltage)• Appropriate Vout Error (error in the approximate value of the voltage)• Approximate Temp. Error (error in the approximate value of the voltage (temperature conversion ))• Temperature Approximation (approximate value of the output temperature)• Approximate Temp. Error versus Vout (error in the approximate value of the temperature)• Approximate Temp. Error (error in the approximate value of the temperature (with respect to thetemperature))⚫ The characteristics data of each graph can be saved as a CSV file. Also, it can be printed out.
⚫ Multiple circuits (Circuit 0 + Circuit 1 + ...) can be simulated simultaneously, and also the results canbe compared under each set of conditions.
⚫ The recommended value of the voltage dividing resistor can be calculated.
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2. Quick Operation Guide
2-1. Simulation Graph Display⚫ Start the software, then select (1) item No. and (2) circuit diagram, and click (3),the screen switches over, and, as shown on the next page, graphs representing the results ofsimulation are displayed.

(2)
(1)

(3)

5
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2. Quick Operation Guide
2-2. Overwriting Graphs⚫ The circuit diagram and the parameters of the NTC thermistor are displayed on [NTC Thermistor
Simulation] (the parameter values can be changed).
⚫ Click, then select a different circuit diagram or a product using the same procedure as thatindicated on the previous page and click, the results of simulation of the different circuit areadded to the existing graphs, enabling a comparison to be made.
Simulation
parameters

The new simulation results areadded to the graphs.

6
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2. Quick Operation Guide
2-3. Comparison and Output of Simulation⚫ By changing the conditions of Circuit 0, Circuit 1, ..., the results of each simulation can be comparedwith each other on the same graph (after changing the conditions, click).
⚫ You can save a curved line on a graph to a text file (CSV format).
⚫ You can print out graphs.
<An example of comparing 2 simulation results>

You can save the resultsin text format.
You can print out the simulation
conditions and results.

7
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3. Details of Operation
3-1. Selecting the Desired Type of NTC Thermistor⚫ You can select an NTC thermistor for general use or an NTC thermistor for automotive.
By clicking [NTC Thermistors for consumer application] or [NTC Thermistors for Automotive・highreriability application(Meet AECQ-200)], the type of thermistor is switched over.

8
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3. Details of Operation
3-2. Selecting a Simulation Circuit⚫ Select the item No. and the circuit diagram.
You can select up to 10 circuits (a resistance grounding circuit, 2 NTC thermistor grounding circuits,
and 5 circuits at the resistor insertion positions).
After making a selection, click. The simulation results will be displayed on a graph.

9
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3. Details of Operation
3-3. Changing/Setting the Simulation Conditions (1/7)⚫ You can freely change each item in the [NTC Thermistor Simulation] window.

<About the voltage parameters>• Compare Mode (comparison mode)If you click, and then select [Voltage Error] followed by [Diff], the following items will be
displayed (this function can be used only when multiple circuits are selected).
When you remove the Compare Mode check, all of the circuits change to Center (the mode
ceases to be the comparison mode), and the values of each circuit are displayed.
・Vout Error H: Difference between the upper limit value of the output and the output
voltage of Circuit 0 to Circuit n・Vout Error L: Difference between the lower limit value of the output and the output
voltage of Circuit 0 to Circuit n・Vout Difference+ : Difference between the upper limit value of the output voltage ofCircuit n and the output voltage of Circuit (n-1)
・Vout Difference : Difference between the output voltage of Circuit n and the output
voltage of Circuit (n-1)
・Vout Difference- : Difference between the lower limit value of the output voltage ofCircuit n and the output voltage of Circuit (n-1)• Approximation
Display/non-display of error graph(Refer to [3-3 Changing/Setting the Simulation Conditions (6/6)].)• Vin (V)
Input voltage (The initial value is 3 [V]).
• Vin Tolerance
Used to enter the input voltage tolerance (the initial value is 0.0 [%]).

10
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3. Details of Operation
3-3. Changing/Setting the Simulation Conditions (2/7)<About the fixed resistor parameters>• R1 Recommend (kohm)
Recommended resistance value of R1
If the lower limit temperature is T1, the upper limit temperature is Th, the output voltage attemperature T1 is Vout (T1), and the output voltage at temperature Th is Vout (Th), the value of
R1 in the case where the following formula holds will be the recommended value.
• R1 (kohm)
Resistance value (R)V
𝑇ℎ +𝑇𝑙 𝑉𝑜𝑢𝑡 𝑇ℎ +𝑉𝑜𝑢𝑡 （𝑇𝑙）=to the selected simulation circuit (R1 to R3).
The number of resistors selected differs 𝑜𝑢𝑡
according2
2
The initial value differs according to the selected simulation circuit.
• R1 Tolerance (%)
Resistance tolerance (R Tolerance)
The number of resistances differs according to the selected simulation circuit (R1 to R3).
The initial value is 1 (%).
• R1 TCR (ppm/deg.C)
Resistor temperature coefficient (R TCR)
The number of resistors differs according to the selected simulation circuit (R1 to R3).
The initial value is 200 [ppm/C].

11
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3. Details of Operation
3-3. Changing/Setting the Simulation Conditions (3/7)<Setting the parameters>• Thermal Dissipation ConstantHeat dissipation constant. The initial value is calculated based on the assumption of 3 mw/C(assuming surface mounting of the NCP15 Series).
Heat dissipation constant depends on the size of the NTC element.
Please change the heat dissipation constant as follows depending on the element size.

SeriesHeat dissipation
constant [mW/℃]

NCP02 Series

2

NCP03 Series

2

NCP15,NCU15 Series

2.5

NCP18,NCU18 Series

312
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3. Details of Operation
3-3. Changing/Setting the Simulation Conditions (4/7)<Parameters of the selected thermistor>• NTC P/N
Item No. selected from the item No. list
Below this item No., R25 (kohm), the resistance tolerance, B (25/50) (K), and the B
constant coefficient tolerance (%) of the selected item No. are displayed.
13
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3. Details of Operation
3-3. Changing/Setting the Simulation Conditions (4/6)⚫ You can change the settings of the graph parameters and the displayed graph by clicking.

<Setting the parameters>• Temp L[deg.C]
Lower limit temperature (Temp L).
• Temp H[deg. C]
Upper limit temperature (Temp H).

14
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3. Details of Operation
3-3. Changing/Setting the Simulation Conditions (5/6)<Graph parameters (1/2)>• Outline Voltage
Output voltage. When this item is selected, the following items are displayed.
・Vout_typ
・Vout_max
・Vout_min: Output voltage at Circuit 0 to Circuit n: Upper limit value of the output voltage at Circuit 0 to Circuit n: Lower limit value of the output voltage at Circuit 0 to Circuit n• Voltage Error
Output voltage error graph. When you select [Diff] in the [NTC Thermistor Simulation] window
and then select this item, the following items are displayed.
・Vout Error H: Upper limit value of the output at Circuit 0 to Circuit n・Vout Error L: Lower limit value of the output at Circuit 0 to Circuit n・Vout Difference+ : Difference between the upper limit value of the output voltage at
Circuit n and the output voltage at Circuit (n-1)
・Vout Difference :Difference between the output voltage at Circuit n and the output
voltage at Circuit (n-1)
・Vout Difference- : Difference between the lower limit value of the output voltage at
Circuit n and the output voltage at Circuit (n-1)• Temperature Error
Temperature conversion error graph. When you select this item, the following items are displayed.
・Temperature Error L at Circuit 0 to n・Temperature Error H at Circuit 0 to n・Temp Difference+・Temp difference・Temp Difference-: temperature conversion graph of Vout Error L: temperature conversion graph of Vout Error H: Value resulting from the conversion of [VoutDifference+] into the temperature at Circuit (n-1): Value resulting from the conversion of [VoutDifference] into the temperature at Circuit (n-1): Value resulting from the conversion of [VoutDifference-] into the temperature at Circuit (n-1)
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3. Details of Operation
3-3. Changing/Setting the Simulation Conditions (6/6)<Graph parameters (2/2)>• Self Heating
Self-heating graph. When you select this item, self-heating (Self Heating [C]) at Circuit 0 to n isdisplayed.
• Voltage Gain
Graph of output voltage per unit temperature. When you select this item, the output voltage perunit temperature (Vout Gain [mV/C]) at Circuit 0 to n is displayed.
• Vout Approximation
Graph indicating approximate value of the output voltage. When you select [Approximation] in the[NTC Thermistor Simulation] window and then select this item, the following items are displayed.
• Graph of Vout-type (center value of the output voltage) and Vout Approximation(approximate value of the output voltage) at Circuit n• Graph of Approximate Vout Error (error in the approximate value of the voltage)• Error in the Approximate Temp. Error (error in the approximate value resulting
from temperature conversion)* “Degree” is the order of the above approximation formula• Temperature Approximation
Graph indicating the approximate value of the temperature versus the output voltage. When you
select [Approximation] in the [NTC Thermistor Simulation] window and then select this item, thefollowing items are displayed.
• Graph of Temp-typ (center value of the voltage) and Temp Approximation(approximate value of the temperature versus the output voltage) of Circuit n.
• Graph of Approximate Temp. Error versus Vout (error in the approximate valueof the temperature with respect to voltage)• Graph of Approximate Temp. Error versus Temp (error in the approximate value
with respect to temperature)* “Degree” is the order of the above approximation formula16
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3. Details of Operation
3-4. Saving a Text File
You can save data in the CSV format.

You can also do this by using the icons in each graph.
17
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3. Details of Operation
3-5. Printing
You can print out displayed graphs.
<Example of printout screen>

You can also do this by using the icons in each graph.
18
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3. Details of Operation
3-6. Making a Mark on a Graph⚫ By clicking a desired point on the graph, you can mark a point you want to measure. The marked
position can be canceled by clicking again.

You can move the marking
point by inputting any
number.

click

19
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This is the end of the operation
manual. To enable maximum usageof the software, techniques anddetailed descriptions of operation
procedures will be introduced fromthe next page on.

20

Copyright © Murata Manufacturing Co., Ltd. All rights reserved.

23 August 2023

Contents
page
1. About This Tool
1-1. Outline
1-2. Main Functions

34

2. Quick Operation Guide
2-1. Simulation Graph Display
2-2. Overwriting Graphs
2-3. Comparison and Output of Simulation

56
7

3. Details of Operation
3-1. Selecting the Desired Type of NTC Thermistor
3-2. Selecting a Simulation Circuit
3-3. Changing/Setting the Simulation Conditions
3-4. Saving a Text File
3-5. Printing
3-6. Making a Mark on a Graph

8
9
10
17
18
19

4. About Circuit Patterns

22

5. Software Use Examples
5-1. circuit that achieves your desired output
28
5-2. Circuit Design That Maximizes Output Voltage Gain Through Arbitrary
Temperature
33
6. Version Confirmation and Contact Method
Appendix Preferred Numbers

38
39
Copyright © Murata Manufacturing Co., Ltd. All rights reserved. 201921

4. About Circuit Patterns
4-1. NTC Thermistor Positions and Output Voltage
There are 10 types of circuit patterns on Simsurfing that are classified under 2 groups
depending on the NTC thermistor position. Furthermore, you can change the output
voltage by adding fixed resistors and changing the resistance value.

(1) Position the thermistor between
Vout-GND⇒Vout-Temp tilt is positive(2) Position the NTC thermistor
between Vin-Vout⇒Vout-Temp tilt is negative

circuit1

circuit022
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4. About Circuit Patterns
4-2. Effects of Voltage Dividing Resistance Value R1
By changing the voltage dividing resistance R1 parameter, theentire output voltage graph can be moved in the parallel
direction.

R1UP

R1DOWN23
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4. About Circuit Patterns
4-3. Effects of Parallel Resistance Value R2
By changing the parallel resistance R2 parameter, the tilting of theoutput voltage graph can be changed. The higher the R2 value, theoutput voltage of the lower temperature side becomes smaller.

※*If “0” is input in R2, the resistance value becomes ∞.
(Open state)

R2UP

24
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4. About Circuit Patterns
4-4. Effects of Series Resistance Value R3
By changing the series resistance R3 parameter, the tilting of theoutput voltage graph can be changed. The higher the R3 value, theoutput voltage of the higher temperature side becomes smaller.

※*If “0” is input in R3, the resistance value becomes 0.
(Short circuit state)

R3UP

25
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4. About Circuit Patterns
4-5. Circuit Pattern Summary
You can change the outline of the output voltage graph by using thevoltage dividing resistance R1, parallel resistance R2, and series
resistance R3.
Parallel resistance R2⇒Related to the Vout size on
the low temperature side

R2

Series resistance R3⇒Related to the Vout sizeon the high temperature
side

R3

R2UP

Voltage dividing resistance R1⇒Related to the Vout size

R1UP
R3UP
R1

R1DOWN26
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Contents
page
1. About This Tool
1-1. Outline
1-2. Main Functions

34

2. Quick Operation Guide
2-1. Simulation Graph Display
2-2. Overwriting Graphs
2-3. Comparison and Output of Simulation

56
7

3. Details of Operation
3-1. Selecting the Desired Type of NTC Thermistor
3-2. Selecting a Simulation Circuit
3-3. Changing/Setting the Simulation Conditions
3-4. Saving a Text File
3-5. Printing
3-6. Making a Mark on a Graph

8
9
10
16
17
18

4. About Circuit Patterns

21

5. Software Use Examples
5-1. circuit that achieves your desired output
27
5-2. Circuit Design That Maximizes Output Voltage Gain Through Arbitrary
Temperature
32
6. Version Confirmation and Contact Method
Appendix Preferred Numbers

37
38
Copyright © Murata Manufacturing Co., Ltd. All rights reserved. 201927

5. Software Use Examples

5-1-1. Circuit Design Using Series Resistance andParallel ResistanceDesign a circuit that achieves your desired output using thissoftware.

-Design Example 1Thermistor used

:NCP15XH103F

R2

Circuit: right diagram (voltage dividing
resistance R1 + parallel resistance R2)
Operating temperature range:0℃～100℃
Input voltage Vin
voltage fluctuation):1V(assuming there are no
R1

Output voltage Vout :0.4V@10℃, 0.7V@60℃
28
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5. Software Use Examples

5-1-2. Selection of Circuit, Thermistor used
Thermistor used
Circuit:NCU15XH103F:Bottom diagram (voltage dividing resistanceR1, parallel resistance R2)
Operating temperature range :0℃～100℃
Input voltage Vin :1V(assuming there are no voltage fluctuation)
Output voltage Vout :0.4V@10℃,
0.7V@60℃

(2)

(1)

(3)

(1) Select a thermistor(2) Select a circuit(3) Perform simulation
29
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5. Software Use Examples

5-1-3. Setting the Operating Temperature,
Input Voltage
Thermistor used
Circuit:NCU15XH103F:Bottom diagram (voltage dividing resistanceR1, parallel resistance R2)
Operating temperature range :0℃～100℃
Input voltage Vin :1V(assuming there are no voltage fluctuation)
Output voltage Vout :0.4V@10℃,
0.7V@60℃(1)(2)(1) Set the operating temperature
range(2) Set the input voltage(3) Pressing
displays thesimulation result
30
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5. Software Use Examples

5-1-4. Displaying Multiple Circuits
Thermistor used
Circuit:NCU15XH103F:Bottom diagram (voltage dividing resistanceR1, parallel resistance R2)
Operating temperature range :0℃～100℃
Input voltage Vin :1V(assuming there are no voltage fluctuation)
Output voltage Vout :0.4V@10℃,
0.7V@60℃

The current R1, R2 does not match your desired Vout.
Press
to display multiple circuits and seek R1, R2
until you find your desired Vout.

31
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5. Software Use Examples

5-1-5. Correlation Between R1 and Output Voltage
Thermistor used
Circuit:NCU15XH103F:Bottom diagram (voltage dividing resistanceR1, parallel resistance R2)
Operating temperature range :0℃～100℃
Input voltage Vin :1V(assuming there are no voltage fluctuation)
Output voltage Vout :0.4V@10℃,
0.7V@60℃

Adjust the R1, R2 value referring to the page 25.
In this case, setting to R1=6.2kΩ, R2=22kΩ will achieve your desired Vout.

32
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5. Software Use Examples

5-2-1. Circuit Design That Maximizes Output
Voltage Gain Through Arbitrary Temperature
Next, design a circuit that raises the Vout gain
through arbitrary temperatures.
-Design Example2Thermistor used:NCP03WF104F

Circuit：right diagram

Operating temperature range:0℃～60℃

Input voltage Vin :3V(assuming there are no
voltage fluctuation)
Circuit Design Condition: Design a circuit in which
the output voltage fluctuation rises the most in
the 50℃ range
33
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5. Software Use Examples

5-2-2. Selection of Circuit, Thermistor used
Thermistor used :NCP03WF104F
Circuit: Bottom diagram
Operating temperature range :0℃～60℃
Input voltage Vin :3V(assuming there are no voltage fluctuation)
Circuit Design Condition :Circuit in which the output voltage
fluctuation rises the most in the 50℃ range

(2)

(1)

(3)

(1) Select a thermistor(2) Select a circuit(3) Perform simulation
34
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5. Software Use Examples

5-2-3. Optimizing Fixed Resistance Values
Thermistor used :NCP03WF104F
Circuit: Bottom diagram
Operating temperature range :0℃～60℃
Input voltage Vin :3V(assuming there are no voltage fluctuation)
Circuit Design Condition :Circuit in which the output voltage
fluctuation rises the most in the 50℃ range

Seek the R1 in which the voltage fluctuation rises the most in the 50℃ range.
(1)

(2)

(1) Set the temperature so the center value of
Temp_L, Temp_H becomes 50℃.
(2) Set R1 to the same value as R1_Recommend.
*R_1Recommend indicates the R1 value when thevoltage fluctuation of the central value of theselected temperature range rises the most(becomes Vout = 1/2 Vin).
35
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5. Software Use Examples

5-2-4. Changing the Operating Temperature Range
Thermistor used :NCP03WF104F
Circuit: Bottom diagram
Operating temperature range :0℃～60℃
Input voltage Vin :3V(assuming there are no voltage fluctuation)
Circuit Design Condition :Circuit in which the output voltage
fluctuation rises the most in the 50℃ range

Change the temperature area again to 0℃ - 60℃.

Using the value set previously for R1, a circuitdesign with a large voltage fluctuation in 50℃ is
36achieved.
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Contents
page
1. About This Tool
1-1. Outline
1-2. Main Functions

34

2. Quick Operation Guide
2-1. Simulation Graph Display
2-2. Overwriting Graphs
2-3. Comparison and Output of Simulation

56
7

3. Details of Operation
3-1. Selecting the Desired Type of NTC Thermistor
3-2. Selecting a Simulation Circuit
3-3. Changing/Setting the Simulation Conditions
3-4. Saving a Text File
3-5. Printing
3-6. Making a Mark on a Graph

8
9
10
16
17
18

4. About Circuit Patterns

21

5. Software Use Examples
5-1. circuit that achieves your desired output
27
5-2. Circuit Design That Maximizes Output Voltage Gain Through Arbitrary
Temperature
32
6. Version Confirmation and Contact Method
Appendix Preferred Numbers

37
38
Copyright © Murata Manufacturing Co., Ltd. All rights reserved. 201937

6. Version Confirmation and Contact Method⚫ Access the contact form on our website from the following link.

38
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Appendix

Preferred Numbers

39
Copyright © Murata Manufacturing Co., Ltd. All rights reserved. 2019