POSITIVE THERMISTORS "Posi-R"
CAT.8100B
General Observations
1. Do not use"Posi-R" in the presence of oil or water.The parts could fail.
2. Do not apply voltage in excess of the rated voltage
.
This could cause a short circuit or burn-out.
3. Do not use "Posi-R" with reactive gas,reducing gas, or oxygen-free environment
-
electrical characteristics may deteriorate or
burn-out may occur.
Notes on Usage
1. Please use the parts within the rated operating temperatures according to the catalog.
2. Please use the parts wihtin the maximum operating voltage and maximum inrush current as specified in the catalog.
3. The surface temperatures for the "Posi-R" during operation are:
for overcurrent protection 100 to 160˚C
Please take into consideration the effect of generated heat around the "Posi-R"
4. Excessive press or shock (ex. drop) should not be applied to the "Posi-R".
5. Do not apply more lead stress than specified.
6. Do not allow flux to come in contact with "Posi-R", it may cause failure.
7. The outer resin on the leads may be partially peeled off. This will not affect the function of products.
8. In case of gluing "Posi-R", the outer resin may be come off, please contact us in this case.
Notes on Storage
1. Packaged parts should be stored under the following conditions:
temperature:
–
10 to +40˚C
humidity:85% or less
2. Storage of "Posi-R" devices may result in increased resistive characteristics. They will return to the initial value by applying
max. operating voltage prior to using the parts.
3. Shall be used shortly after opening the package. The prolonged exposure to the air may case to deteriorate the solderability.
APPLICATION GUIDELINES FOR POSITIVE THERMISTORS, "Posi-R"
Characteristics of Positive Thermistors "Posi-R"
•Switching Temperature (Resistance Anomaly Point)
At the resistance / temperature characteristics of positive thermistors "Posi-R", the temperature which the resistance value becomes
twice as high as that of at 25˚C, is called as "switching temperature" (Curie point)
Thermistors "Posi-R" show anomalous temperature characteristics of resistivity, and typical characteristics are represented in Fig. 1.
Optimum characteristics can be selected for each application.
•Temperature Coefficient
The temperature coefficient is calculated from the linear range at the steepest portion of resistance
(T1to T2)
as illustrated in Fig. 2.
Temperature coefficient = 2.303 ( log10 R2 / R1) ×100 (%/ ˚C)
t2–t
1
Maximum Inrush Current
The maximum inrush current is the maximum allowable current (effective value) flowed into a Posi-R. No current higher than this shall
be flowed as it causes breakdown of a Posi-R.
Recovery Time
The recovery time is the time constant necessary for a Posi-R to quickly return to the switching temperature (resistance of twice as high
as the initial value) after the power source is cut off.
Dissipation Factor
When a power source is applied to Posi-R and thermal equilibrium will have been reached, the following equation is established.
V •I = C (T1–T0)
Where,V : Applied voltage (V)
I : Equilibrium current (A)
C : Dissipation factor (W/˚C)
T1 : Equilibrium temperature of Posi-R (˚C)
T0 : Ambient temperature (˚C)
In case that the dissipation factor is known by putting arbitrary values of voltage and current into the above equation, the equilibrium
temperature at the then voltage can be attained.
The temperature rise (T1 –T0) of Posi-R due to voltage application can be also computed easily.
10
5
10
4
10
3
10
2
10
1
10
-1
–50 0 50 100 150 200 250
Fig. 1 Resistance / Temperature Characteristics
Temperature (˚C)
BT CA CJ
BL CN
CE
Resistance ratio (1 at 25˚C)
POSITIVE THERMISTORS "Posi-R"
CAT.8100B
POSITIVE THERMISTORS "Posi-R"
CAT.8100B
V
A
Fig. 3 Measuring Circuit
"Posi-R"
Fig. 4 Voltage / Current Characteristics
Current long
10
1
1
1
1
2
E
1
E
2
Voltage log
10
E
Fig. 2 Temperature Characteristics of "Posi-R"
Temperature (˚C)
Resistance log
10
R
R
2
R
1
T
1
t
1
t
2
T
2
• Voltage / Current Characteristics
In the Fig. 3 circuit, the relationship between voltage and current is called as the voltage/current characteristics when the voltage is
applied to Posi-R and it gets the thermal equilibrium.
As seen in Fig. 4, the characteristic follows Ohm's law up to E1 point. The current increases when the voltage is raised, provided that
the temperature characteristics is within the range of switching temperature or lower. The range between E1and E2is over the
switching temperature but within the constant range of power dissipation. However, beyond E2point, an excess power will run and
Posi-R will result in breakdown, accordingly.
Therefore, the operating voltage of Posi-R shall be lower than E2, and its rated voltage shall be defined to half of E2value or lower,
taking the safety into account.
POSITIVE THERMISTORS "Posi-R"
CAT.8100B
• Equilibrium Current, Equilibrium Resistance
The current, which Posi-R gets thermal equilibrium with an arbitrary voltage application (for 30 seconds or longer), is called as the
equilibrium current.
Besides, the quotient which the applied voltage is divided by the equilibrium current is specified as the equilibrium resistance.
• Current , Time Characteristics
In the Fig. 5 circuit, when a load resistance (R) and a Posi-R are connected in series and an arbitrary voltage higher than E1in Fig. 4 is
applied, the Posi-R will have inherent temperature due to a current flowing through it. Its temperature rises as time passes by, and it
exceeds the switching temperature in a certain time, resulting in a rapid damp of the current. The trip time can be adjusted by the
current volume as shown in Fig. 6.
By making use of these characteristics, a Posi-R can be used for the following applications;
1. Timing circuit
2. Switching use for motor starting
3. Overcurrent protection
When the parameters of I1, t1, I2and t2in Fig. 6 are expressed in a logarithmic graph in the manner of Fig. 7, an almost linear graph is
formed and the relationship between the circuit current and the trip time can be obtained.
But, when a Posi-R is used for a timing application such as a timer, the voltage shall be appropriately applied for 30 seconds or less
as the changes of conditions may affect much more as time passes by.
Fig. 5 Measuring Circuit
Posi-R
R
A
Current
I
1
I
2
t
1
t
2
Time
Fig. 6 Current / Time Characteristics
Current log
10
I
I
1
I
2
t
1
t
2
Time log
10
t
Fig. 7 Current / Time Characteristics
POSITIVE THERMISTORS "Posi-R"
CAT.8100B
Type numbering system
(Example for overcurrent protection 12V. 2.2Ω)
Z
1P
2 3 4 5 6 7 8910 11
Type (Posi-R)
Configuration
Revision Code
Switching Temperature (Example)
Usage
Nominal Resistance
Temperature
Code
BL
BN
BX
Nominal resistance
Code
0.5Ω0R5
1.0Ω1R0
2.2Ω2R2
10Ω100
100Ω101
1kΩ102
Application Code
For overcurrent protection
Disc type
For square type temperature heater
For thermal sensing
For refrigerator motor starting
Others Appliance
C
D
S
P
For air conditioner R
M
Z
150˚C
160˚C
110˚C
190˚C
120˚C
135˚C
CC
CE
CH
C11CE2R2A
POSITIVE THERMISTORS "Posi-R"
CAT.8100B
For Overcurrent Protection
When something abnormal occurs at the load such as a transistor circuit or a small-type motor, an abnormal current rushes into the
power source circuit. Then, a power transistor at the transformer or the switching power supply generates heat in an abnormal level
and causes breakdown.
If a Posi-R for overcurrent protection is used in such a circuit, it can make the temperature compensation and protection for the power
source and the load. An example is as shown in Fig. 8.
As to the temperature protection, it can be perfectly made in use of this Posi-R owing to the excellent characteristics of resistance
anomaly, that is, a current is reduced by the increased resistance due to the selfheating of Posi-R.
At the voltage/current characteristics in Fig. 9, there is a peak current. If a current larger than this peak current flows, a Posi-R acts.
But if a current less than the peak current flows, a Posi-R does not act. The peak current varies depending upon the size of Posi-R,
resistance and ambient temperature. Fig. 10 shows an example of current characteristics.
At the current higher than the upper limit of fluctuation range, a Posi-R acts. Contrary, at the current less than the lower limit, it does
not act. But the fluctuation range varies owing to ambient temperature.
For instance, if the operating temperature range is supposed to be at –10 to +60˚C, the lower limit at +60˚C becomes the maximum
value for a normal current (non-acting) and the upper limit at –10˚C becomes the minimum value for a limiting current (acting),
respectively.
Judging from the above explained relations, a Posi-R can be suited for the circuit where the ratio of a limiting current to a normal current
is more than 2.5 to 3 times.
power source
power source
Load
Load
Power source circuit (Primary)
Motor circuit Transistor circuit
power
source
Load
Power source circuit (Secondary)
Posi-R
Posi-R
Posi-R
Posi-R
Motor
Fig. 8 Examples of applications
M
Current (mA)
1000
500
300
200
100
50
123 10205
Voltage (VAC)
Fig. 9 Voltage / Current Characteristics
–10˚C
25˚C
60˚C
Characteristics of ZPC4MCE100D
Peak current
POSITIVE THERMISTORS "Posi-R"
CAT.8100B
Fluctuation range
Normal current (Non-acting)
Current (mA)
Characteristic of ZPC4MCE100D
600
400
300
500
200
100
–10˚C25˚C60˚C
Ambient temperature
Fig. 10 Current Characteristics
Limiting current (Acting)
104
103
102
10
1
0.1 50 100 150 2000
Temperature (˚C)
Fig. 11 Resistance / Temperature Characteristics
Resistance ratio (1 at 25˚C)
