NC12N00563JBA - AVX Corporation - Datasheet.Directory

AVX

NTC Thermistors

Contents

NTC Thermistors

NTC THERMISTORS

General Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Application Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Selection Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Ordering Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

RoHS/ELV Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

NTC SMD Thermistors

NC 12 - NC 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

With Nickel Barrier Termination NB 12 - NB 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

With Nickel Barrier Termination NB 21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Surface Mounting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

NTC Accurate

NJ 28 - NI 24 - NK 20 - NP 30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

NTC Disc Thermistors

ND 03/06/09 - NE 03/06/09 - NV 06/09. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

NTC Leadless Disc Thermistors

NR Series for Consumer and Automotive Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Resistance

Tables of Resistance vs Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Identification – Traceability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

As we are anxious that our customers should benefit from the latest developments in the technology and standards,

AVX reserves the right to modify the characteristics published in this brochure.

NOTICE: Specifications are subject to change without notice. Contact your nearest AVX Sales Office for the latest specifications. All statements,

information and data given herein are believed to be accurate and reliable, but are presented without guarantee, warranty, or responsibility of any kind,

expressed or implied. Statements or suggestions concerning possible use of our products are made without representation or warranty that any such

use is free of patent infringement and are not recommendations to infringe any patent. The user should not assume that all safety measures are

indicated or that other measures may not be required. Specifications are typical and may not apply to all applications.

1 – INTRODUCTION

NTC thermistors are thermally sensitive resistors made from

a mixture of Mn, Ni, Co, Cu, Fe oxides. Sintered ceramic

bodies of various sizes can be obtained. Strict conditions

of mixing, pressing, sintering and metallization ensure an

excellent batch-to-batch product characteristics.

This semi-conducting material reacts as an NTC resistor,

whose resistance decreases with increasing temperature.

This Negative Temperature Coefficient effect can result from

an external change of the ambient temperature or an inter-

nal heating due to the Joule effect of a current flowing

through the thermistor.

By varying the composition and the size of the thermistors,

a wide range of resistance values (0.1Ω to 1MΩ) and tem-

perature coefficients (-2 to -6% per °C) can be achieved.

RoHS (Restriction of Hazardous Substances - European

Union directive 2002/95/EC).

ELV (End of Life-Vehicle - European Union directive

2000/53/EC).

All Thermistor Products have been fully RoHS/ELV since

before 2006.

Chip Thermistor NB RoHS/ELV Status: external Plating

100% smooth semi-bright Sn as standard SnPb Termination

available on request.

2 – MAIN CHARACTERISTICS

2.1 CHARACTERISTICS WITH NO DISSIPATION

2.1.1. Nominal Resistance (Rn)

The nominal resistance of an NTC thermistor is generally

given at 25°C. It has to be measured at near zero power

so that the resultant heating only produces a negligible

measurement error.

The following table gives the maximum advised measure -

ment voltage as a function of resistance values and thermal

dissipation factors.

This voltage is such that the heating effect generated by the

measurement current only causes a resistance change of

1% ΔRn/Rn.

2.1.2. Temperature -

Resistance characteristics R (T)

This is the relation between the zero power resistance and

the temperature. It can be determined by experimental mea-

surements and may be described by the ratios R (T) /R

(25°C) where:

R (T) is the resistance at any temperature T

R (25°C) is the resistance at 25°C.

These ratios are displayed on pages 29 to 33.

2.1.3. Temperature coefficient (α)

The temperature coefficient (␣) which is the slope of the

curve at a given point is defined by:

100 dR

␣= • and expressed in % per °C.

RdT

2.1.4. Sensitivity index (B)

The equation R = A exp (B/T) may be used as a rough

approximation of the characteristic R (T).

B is called the sensitivity index or constant of the material

used.

To calculate the B value, it is necessary to know the resis-

tances R1and R2of the thermistor at the temperatures

T1and T2.

The equation: R1= R2exp B ()

leads to: B (K) = 1• ᐍn ()

Conventionally, B will be most often calculated for tempe-

ratures T1= 25°C and T2= 85°C (298.16 K and 358.16 K).

In fact, as the equation R = A exp (B/T) is an approximation,

the value of B depends on the temperatures T1and T2by

which it is calculated.

For example, from the R (T) characteristic of material M

(values given on page 29), it can be calculated:

B (25 – 85) = 3950

B (0 – 60) = 3901

B (50 – 110) = 3983

When using the equation R = A exp (B/T) for this material,

the error can vary by as much as 9% at 25°C, 0.6% at 55°C

and 1.6% at 125°C.

Using the same equation, it is possible to relate the values of

the index B and the coefficient α:

1dR

␣= • • A exp (B/T) •

RdT

thus ␣= – expressed in %/°C

NTC Thermistors

General Characteristics

Ranges of Maximum measuring voltage

values (V)

(Ω)

δ= 2 mW/°C δ= 5 mW/°C δ= 10 mW/°C δ= 20 mW/°C

R 10 0.10

10 < R 100 0.13 0.18 0.24

100 < R 1,000 0.25 0.38 0.53 0.24

1,000 < R 10,000 0.73 1.1 1.5 2.0

10,000 < R 100,000 2.1 3.2 4.6

R < 100,000 6.4 9.7 14.5

1 -1

1T2

()

1 -1

1T2

A exp (B/T)

-B

NTC Thermistors

General Characteristics

2.1.5. Further approximation of R (T) curve

The description of the characteristic R (T) can be improved

by using a greater number of experimental points, and by

using the equation:

1= A + B (ᐍ

n R) + C (ᐍ

n R)3

The parameters A, B and C are determined by solving the

set of equations obtained by using the measured resis-

tances at three temperatures.

The solution of the above equation gives the resistance at

any temperature:

The precision of this description is typically 0.2°C for the

range –50 to +150°C (A, B, C being determined with exper-

imental values at –20, +50 and 120°C) or even better if this

temperature range is reduced. The ratios R(T)/R(25°C) for

each of the different materials shown on pages 29 to 33

have been calculated using the above method.

2.1.6. Resistance tolerance and temperature

precision

An important characteristic of a thermistor is the tolerance

on the resistance value at a given temperature.

This uncertainty on the resistance (DR/R) may be related to

the corresponding uncertainty on the temperature (DT),

using the relationship:

⌬T = 100 • ⌬R•1

R␣

Example: consider the thermistor ND06M00152J —

• R (25°C) = 1500 ohms

• Made from M material

• R (T) characteristic shown on page 23 gives:

␣= - 4.4%/°C at 25°C

• Tolerance ⌬R/R = ±5% is equivalent to:

⌬T = 5%/4.4%/°C = ±1.14°C

2.1.7. Resistance tolerance at any temperature

Any material used for NTC manufacturing always displays a

dispersion for the R (T) characteristic.

This dispersion depends on the type of material used

and has been especially reduced for our accuracy series

thermistors.

Thus, the tolerance on the resistance (⌬R2/R2) at a temper-

ature T2is the sum of two contributions as illustrated on

Figure 1:

– the tolerance ⌬R1/R1at a temperature T1used as a

reference.

– an additional contribution due to the dispersion on

the characteristic R (T) which may be called

“Manufacturing tolerance” (Tf).

Figure 1

Differentiating the equation R = A exp (B/T), the two contri-

butions on the tolerance at T can also be written:

⌬R2=⌬R1+⎪⎪• ⌬B

R2R1

The T(f) values given with the resistance – temperature

characteristics on pages 29 to 33 are based on a computer

simulation using this equation and experimental values.

2.1.8. Designing the resistance tolerances

Using the fact that the coefficient ␣decreases with temper-

ature (α= –B/T2), it is generally useful to define the closest

tolerance of the thermistor at the maximum value of the

temperature range where an accuracy in °C is required.

For example, let us compare the two designs 1 and 2

hereafter:

Only the Design 2 is able to meet the requirement ΔT ⯝1°C

from 25°C to 100°C.

RΩ

R25

25°CTTemperature (°C)

Graph with B

Graph with B ± ΔB

}(ΔR)25°C

}

}(ΔR)25°C

}= (ΔR) T

1-1

1T2

TRαDesign 1 Design 2

(°C) (Ω) (%/°C) ⌬R/R(%) ⌬T(°C) ⌬R/R(%) ⌬T(°C)

0 3275 -5.2 3.5 0.7 5.0 1.0

25 1000 -4.4 3.0 0.7 4.5 1.1

55 300 -3.7 3.5 1.0 4.0 1.1

85 109 -3.1 4.1 1.3 3.4 1.1

100 69.4 -2.9 4.5 1.6 3.0 1.0

A - 1/T

()

A - 1/T

()

ᐍn R (T) =

]

[-27

3 +3

2327 2+ 4 3

冑

()

冑

-3+27

A - 1/T

() ()()

冑

327 2+ 4 3

A - 1/T

()

冑

()

2.1.9. Shaping of the R (T) characteristic

By the use of a resistor network, it is possible to modify the

R (T) characteristic of a thermistor so that it matches the

required form, for example a linear response over a restrict-

ed temperature range.

A single fixed resistor Rp placed in parallel with a thermistor

gives a S–shape resistance–temperature curve (see Figure 2)

which is substantially more linear at the temperature range

around the inflexion point (Ro, To).

Figure 2 – Linearization of a thermistor

It can be calculated that better linearization is obtained when

the fixed resistor value and the mid-range temperature are

related by the formula:

Rp = RTo x B – To

B+ 2To

For example, with a thermistor ND03N00103J —

R25°C = 10kΩ, B = 4080 K

good linearization is obtained with a resistor in parallel where

the value is:

Rp = 10,000 Ω x 4080 - 298 = 8088 Ω

4080 + (2 x 298)

2.1.10. Demonstration of the R (T) parameters

calculation

To help our customers when designing thermistors for

temperature measurement or temperature compensation,

software developed by our engineering department is avail-

able upon request.

2.2 CHARACTERISTICS WITH ENERGY

DISSIPATION

When a current is flowing through an NTC thermistor, the

power due to the Joule effect raises the temperature of the

NTC above ambient.

The thermistor reaches a state of equilibrium when the

power supplied becomes equal to the power dissipated in

the environment.

The thermal behavior of the thermistor is mainly dependent

on the size, shape and mounting conditions.

Several parameters have been defined to characterize these

properties:

2.2.1. Heat capacity (H)

The heat capacity is the amount of heat required to change

the temperature of the thermistor by 1°C and is expressed in

J/°C.

2.2.2. Dissipation factor (␦)

This is the ratio between the variation in dissipated power

and the variation of temperature of the NTC. It is expressed

in mW/°C and may be measured as:

␦= U.I

85 – 25

where U.I is the power necessary to raise to 85°C the tem-

perature of a thermistor maintained in still air at 25°C.

2.2.3. Maximum permissible temperature (T max)

This is the maximum ambient temperature at which the ther-

mistor may be operated with zero dissipation. Above this

temperature, the stability of the resistance and the leads

attachment can no longer be guaranteed.

2.2.4. Maximum permissible power at 25°C (Pmax)

This is the power required by a thermistor maintained in still

air at 25°C to reach the maximum temperature for which it is

specified.

For higher ambient temperatures, the maximum permissible

power is generally derated according to the Figure 3 here-

after and TL = Tmax – 10°C.

Figure 3 – Derating of maximum power

(kΩ)

T (°C)

RTO

max

25°TLTmax T°C

NTC Thermistors

General Characteristics

2.2.5. Voltage – Current curves V (l)

These curves describe the behavior of the voltage drop V

measured across the NTC as the current l through the NTC

is increased.

They describe the state of equilibrium between power

resulting from Joule effect and dissipated power in the

surroundings. (Figure 4)

Figure 4 – Voltage – current curve V (l)

Several zones can be identified:

– low current zone

dissipated energy only produces negligible heating and

the curve V (l) is almost linear.

– non-linear zone

the curve V (l) displays a maximum voltage Vmax for a

current lo.This maximum voltage Vmax and the temper-

ature Tmax reached by the NTC under these conditions

can be determined by using the equations:

P = V2/R = ␦(T - Tamb) and

R = Ramb • exp B (1/T - 1/Tamb)

therefore:

Tmax = B/2 - B2/4 - BTamb ~Tamb

Vmax = ␦(Tmax - Tamb ) • Ramb exp [B(1 - 1 )]

Tmax Tamb

where ␦is the dissipation factor and Tamb is the ambi-

ent temperature.

– high current zone

for higher currents, an increase in temperature of the

NTC decreases the resistance and the voltage more

rapidly than the increase of the current. Above a certain

dissipated power, the temperature of the NTC exceeds

the permissible value.

2.2.6. Current – Time curves l(t)

When voltage is applied to a thermistor, a certain amount of

time is necessary to reach the state of equilibrium described

by the V(l) curves.

This is the heating up time of the thermistor which depends

on the voltage and the resistance on one side and the heat

capacity and dissipation on the other.

The curves l(t) are of particular interest in timing applications.

2.2.7. Thermal time constant

When a thermistor is self-heated to a temperature T above

ambient temperature Tamb, and allowed to cool under zero

power resistance, this will show a transient situation.

At any time interval dt, dissipation of the thermistor

(␦(T – Tamb)dt) generates a temperature decrease –HdT,

resulting in the equation:

1dT = - ␦dt

(T - Tamb)H

The solution to this equation for any value of t, measured

from t = 0, is:

ᐍn(T - Tamb)= - ␦t

(To - Tamb)H

We can define a thermal time constant ␶as:

␶= H/␦expressed in seconds.

Where the time t = ␶:

(T - Tamb) / (To - Tamb) = exp - 1 = 0.368

expressing that for t = ␶, the thermistor cools to 63.2% of the

temperature difference between the initial To and Tamb (see

Figure 5).

According to IEC 539 our technical data indicates ␶mea-

sured with To = 85°C, Tamb = 25°C and consequently

T = 47.1°C.

Figure 5 – Temperature – time curve T(t)

2.2.8. Response time

More generally, it is possible to define a response time as the

time the thermistor needs to reach 63.2% of the total

temperature difference when submitted to a change in the

thermal equilibrium (for example from 60°C to 25°C in

silicone oil 47V20 Rhodorsil).

T (°C)

47.1

25 tt (s)

Vmax

IoI

NTC Thermistors

General Characteristics

( )

1+Tamb

冑

TEMPERATURE MEASUREMENT

High sensitivity and low cost make NTC thermistors the most

common device used for temperature measurement.

Non-linearity of the R -T curve generally leads to the use of

a resistor network to linearize the signal. An example is

given in Figure 6.

More precise measurements and temperature display can

also be achieved with simple electronic equipment as

shown in Figure 7.

The choice of the model will particularly take into account

the small size (better response time) and the resistance

tolerance. Mounting conditions (dissipation), and input volt-

age (self-heating) will also be carefully defined to avoid serious

errors in temperature measurement.

TEMPERATURE CONTROL

AND ALARM

NTC thermistors can be used as a simple on-off control tem-

perature system or temperature alarm system. Figure 8 gives

an example of such a circuit.

When the temperature increases to a defined value, the

resistance of the thermistor decreases and the current

becomes sufficiently high to energize the relay and provide

temperature alarm or heating system turn-off.

The high sensitivity of thermistors (about 4% resistance

change for 1°C) allows the temperature to be controlled very

precisely.

TEMPERATURE COMPENSATION

As many electronic components (integrated circuits, ampli-

fiers,...) have a positive temperature coefficient of resistance,

NTC thermistors represent a cheap and interesting solution

to compensate for this effect and provide an improved

temperature stability for electronic equipment.

It is necessary to include the thermistor in a resistor network

(Figure 10) calculated in such a manner that the network

coefficient compensates exactly for the positive temperature

coefficient of the other component (Figure 9).

Common leaded discs or chip thermistors are well suited for

this application.

Figure 6 Figure 7

NTC Thermistors

Application Notes

RNTC

Thermistor

circuit

A/D

converter

Display T°C

μ processor

with R/T

algorithm

Resistance

Temperature

RTotal

RNTC

Figure 8

Figure 9 Figure 10

LIQUID LEVEL OR FLOW DETECTION

The dissipation of a thermistor is significantly different in a

liquid or in a gas, in a static fluid or in a stirred one. A liquid

level detector or a gas–flow measurement can be designed

using this property.

In Figure 11, the output voltage measured on the thermistor

depends upon the dissipation factor of its environment, and

can be illustrated by V-l curves (Figure 12).

This voltage can be used to detect the presence (V2) or

absence (V1) of liquid around the thermistor or measure the

flow speed.

A good design should define a precise operating temperature

range, where dissipation in the high dissipating medium at

highest ambient temperature remains higher than the dissipa-

tion in low dissipating medium at lowest ambient temperature.

SURGE PROTECTION

A soft start of sensitive apparatus can be achieved by using

NTC thermistors as described in Figures 13 and 14.

At turn-on, the NTC absorbs the surge current, limits the

current across the equipment and protects it. Then, the

thermistor heats, its resistance decreases and most of the

power becomes applied to the apparatus.

In its design, the thermistor will be selected with a thermal

capacity higher than the surge energy to absorb.

TIME DELAY

The current-time characteristic of a thermistor is used in time

delay applications such as delaying energization of a relay

after application of power to an electrical circuit.

The time delay, time necessary for the thermistor to heat up

to the temperature where its resistance allows the current to

reach the switching value of the relay, is mainly defined with

the nominal resistance of the thermistor.

The time delay is also strongly dependent upon the ambient

temperature, as shown in Figure 15.

Figure 11

Figure 12

Figure 15

Current T = 50°C

T = 40°C

T = 25°C

Time

Voltage

Vin

Vin/RS

Current

Vin

RNTC

NTC Thermistors

Application Notes

Figure 13

Figure 14

RNTC

Equipment

Power

Unprotected equipment

Protected equipment

NTC absorbed power

Time

NTC Thermistors

Selection Guide

Types Range of Values Main Applications Page

R at 25°C

SMD - Hybrid circuit

NC 12/20 - Temperature 10

NB 12/20 Compensation 12

NB 21/23 14

Accuracy Series

Leaded Discs

Leadless Discs

- Temperature

measurement

- Temperature

measurement

and regulation

- Level detection

- Compensation

- Automotive

and industrial

thermal control

Custom designed products

generally defined at two temperatures

NJ 28

NI 24

NP 30

NK 20

N.03

N.06

N.09

10 Ω 1 MΩ

2 kΩ 100 kΩ

330 Ω 1 MΩ

150 Ω 330 kΩ

68 Ω 150 kΩ

NC20 K 0 0103 M – –

NTC Thermistors

Ordering Code

Type

NC 12

NC 20

NB 12

NB 20

NB 21

NB 23

NJ 28

NI 24

NK 20

ND 03

ND 06

ND 09

NR ..

Material

Code

(See tables

pages 29 to 33)

Material Code

2nd Digit

NJ, NK Types: A

NB, NC Types:

C or O or 5 or 2

Other Types: 0

Resistance at 25ºC

(EIA Code)

Tolerance

on Resistance

at 25°C

F: ± 1%

G: ± 2%

H: ± 3%

J: ± 5%

K: ± 10%

L: ± 15%

M: ± 20%

X: ± 25%

Suffix

HOW TO ORDER

ROHS/ELV COMPLIANCE BY PRODUCT FAMILY

For leadless discs

(types NR) see

specification and

ordering code on

pages 28.

1. Resistance expressed by two

significant figures

1st digit: 0 (zero)

2nd and 3rd digits: the first two

significant figures of the resistance

value at 25°C.

4th digit:

– for values ≥ 10 Ω:

the number of ZEROS to be

added to the resistance value

– for values ≥ 1 Ωand ≤ 9.9 Ω:

the numerical 9 signifying that the

resistance value is to be multiplied

by 0.1

– for values < 1 Ω: the numerical 8

signifying that the resistance

value is to be multiplied by 0.01

Examples: 1000 Ω: 0102

8.2 Ω: 0829

0.47 Ω: 0478

2. Resistance expressed by three

significant figures

1st, 2nd and 3rd digits: the first three

significant figures of the resistance

value at 25°C.

4th digit:

– for values > 100 Ω:

the number of ZEROS to be

added to the resistance value

– for values > 10 Ωand < 100 Ω:

the numerical 9 signifying that the

resistance value is to be multiplied

by 0.01

– for values > 1 Ωand < 10 Ω:

the numerical 8 signifying that the

capacitance value is to be multiplied

by 0.01

Examples : 196 Ω: 1960

47.2 Ω: 4729

RoHS (Restriction of Hazardous Substances - European Union directive 2002/95/EC).

ELV (End of Life-Vehicle - European Union directive 2000/53/EC).

All Thermistor Products have been fully RoHS/ELV since before 2006.

Chip Thermistor NB RoHS/ELV Status: external Plating 100% smooth semi-bright Sn as standard SnPb Termination available

on request.

Products that are supplied AS STANDARD in RoHS/ELV compliant form for listed

Industrial Product Family RoHS Compliant for Material Listed

Group Series Cadmium Hexavalent Lead Mercury PBBs PBDEs

Chromium

Leaded NTC Thermistors NF NI 444444

Thermistors Thermistors ND NJ NP 444444

SMD Thermistors NC 444444

Thermistors Thermistors NB 444444

LEAD-FREE COMPATIBLE

COMPONENT