CL-70

**NTC THERMISTORS:  TYPE CL** 

## g 

## **NTC DISCS FOR INRUSH CURRENT LIMITING** 

## **DESCRIPTION:** 

Disc thermistor with uninsulated lead-wires. 

## **FEATURES:** 

- [Low cost solid state device for inrush current ] suppression 

- [Excellent mechanical strength] 

- [Wide operating temperature range: -50°C to 175°C] 

- [Suitable for PCB mounting] 

- [Available as a standard with kinked leads and on ] tape and reel to EIA RS-468A for automatic insertion 

|TYPE<br>Fig. 1<br>~~ea~~|Res @<br>25°C<br>±25%<br>(ohms)<br>~~ea~~|Max*<br>Steady<br>State<br>Current<br>AMPS<br>(RMS)<br>~~ea~~|Disc<br>Dia.<br>(Max)<br>(in.)<br>~~ea~~|Disc<br>Thick.<br>(Max)<br>(in.)|Lead<br>Spacing<br>(Ref.)<br>(in.)|Lead<br>Dia.<br>AWG|Cx (max)**<br>µFarads|Cx (max)**<br>µFarads|Equation constants for<br>resistance under load ***|Equation constants for<br>resistance under load ***|Equation constants for<br>resistance under load ***|Approx. Res. Under Load at %<br>Max. Rated Current|Approx. Res. Under Load at %<br>Max. Rated Current|Approx. Res. Under Load at %<br>Max. Rated Current|Approx. Res. Under Load at %<br>Max. Rated Current|Diss.<br>Const.<br>(mW/°C)|Time<br>Const.<br>(sec.)|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
||||||||@120<br>VAC|@240<br>VAC|X|Y|Current<br>Range<br>Min.I / Max.I|25%|50%|75%|100%|||
|CL-11<br>~~ea~~|0.7<br>~~ea~~|12<br>~~ea~~|0.77<br>~~ea~~|0.22|0.328|18|2700|600|0.50|-1.18|4.0≤1≤12|14|.06|.04|.02|25|100|
|CL-21<br>~~ea~~|1.3<br>~~ea~~|8<br>~~ea~~|0.55<br>~~ea~~|0.21|0.328|18|800|200|0.60|-1.25|3.0≤1≤8.0|.25|.09|.06|.04|15|60|
|CL-30|2.5|8|0.77|0.22|0.328|18|6000|1500|0.81|-1.25|2.5≤1≤8.0|.34|.14|.09|.06|25|100|
|CL-40|5|6|0.77|0.22|0.328|18|5200|1300|1.09|-1.27|1.5≤1≤6.0|.65|.27|.16|.11|25|100|
|CL-50|7|5|0.77|0.26|0.328|18|5000|1250|1.28|-1.27|1.5≤1≤5.0|.96|.40|.24|.16|25|120|
|CL-60|10|5|0.77|0.22|0.328|18|5000|1250|1.45|-1.30|1.2≤1≤5.0|1.09|.44|.26|.18|25|100|
|CL-70|16|4|0.77|0.22|0.328|18|5000|1250|1.55|-1.26|1.0≤1≤4.0|1.55|.65|.39|.27|25|100|
|CL-80|47|3|0.77|0.22|0.328|18|5000|1250|2.03|-1.29|0.5≤1≤3.0|2.94|1.20|.71|.49|25|100|
|CL-90|120|2|0.93|0.22|0.328|18|5000|1250|3.04|-1.36|0.5≤1≤2.0|7.80|3.04|1.75|1.18|30|120|
|CL-101|0.5|16|0.93|0.22|0.328|18|4000|1000|0.44|-1.12|4.0≤1≤16|.09|.04|.03|.02|30|120|
|CL-110|10|3.2|0.40|0.17|0.250|24|600|150|0.83|-1.29|0.7≤1≤3.2|1.10|.45|.27|.18|8|30|
|CL-120|10|1.7|0.40|0.17|0.250|24|600|150|0.61|-1.09|0.4≤1≤1.7|1.55|.73|.46|.34|4|90|
|CL-130|50|1.6|0.45|0.17|0.250|24|600|150|1.45|-1.38|0.4≤1≤1.6|5.13|1.97|1.13|.75|8|30|
|CL-140|50|1.1|0.45|0.17|0.250|24|600|150|1.01|-1.28|0.2≤1≤1.1|5.27|2.17|1.28|.89|4|90|
|CL-150|5|4.7|0.55|0.18|0.328|22|1600|400|0.81|-1.26|1.0≤1≤4.7|.66|.27|.16|.11|15|110|
|CL-160|5|2.8|0.55|0.18|0.328|22|1600|400|0.60|-1.05|0.8≤1≤2.8|.87|.42|.27|.20|9|130|
|CL-170|16|2.7|0.55|0.18|0.328|22|1600|400|1.18|-1.28|0.5≤1≤2.7|1.95|.80|.48|.33|15|110|
|CL-180|16|1.7|0.55|0.18|0.328|22|1600|400|0.92|-1.18|0.4≤1≤1.7|2.52|1.11|.69|.49|9|130|
|CL-190|25|2.4|0.55|0.18|0.328|22|800|200|1.33|-1.34|0.5≤1≤2.4|2.63|1.04|.60|.41|15|110|
|CL-200|25|1.7|0.55|0.18|0.328|22|800|200|0.95|-1.24|0.4≤1≤1.7|2.74|1.18|.70|.49|9|130|
|CL-210|30|1.5|0.40|0.20|0.250|24|600|150|1.02|-1.35|0.3≤1≤1.5|3.83|1.50|.87|.60|8|30|



## **OPTIONS:** 

- [For kinked leads, add suffix “A”] 

- [For tape and reel, add suffix “B”] 

- [For tape and reel, add suffix “AB”] 

- [Other tolerances in the range 0.7][Ω][to 120][Ω] 

- [Other tolerances, tolerances at other temperatures] 

- Alternative lead lengths, lead materials, insulations 

## **DATA:** 

*maximum rating at 25ºC or 

Iderated = √ (1.1425–0.0057 x TA)  x  Imax @ 25°C for ambient temperatures other than 25ºC. **maximum ratings 

- ***R0=X1[Y ] where X and Y are found in the table above 

**NTC THERMISTORS:  TYPE CL** 

**==> picture [37 x 37] intentionally omitted <==**

**----- Start of picture text -----**<br>
g<br>**----- End of picture text -----**<br>


## **NTC DISCS FOR INRUSH CURRENT LIMITING** 

**==> picture [151 x 113] intentionally omitted <==**

**----- Start of picture text -----**<br>
R I<br>i [A]<br>-tº<br>zZos<br>TYPICAL POWER SUPPLY CIRCUIT<br>**----- End of picture text -----**<br>


## INRUSH CURRENT LIMITERS IN SWITCHING POWER SUPPLIES 

The problem of current surges in switch-mode power supplies is caused by the large filter capacitors used to smooth the ripple in the rectified 60Hz current prior to being chopped at a high frequency. The diagram above illustrates a circuit commonly used in switching power supplies. 

- Maximum permissible surge current at turn-on 

- Matching the thermistor to the size of the filter capacitors 

- Maximum value of steady state current 

- Maximum ambient temperature 

- Expected life of the power supply 

## Maximum Surge Current 

In the circuit above the maximum current at turn-on is the peak line voltage divided by the value of R; for 120v, it is approximately 120 x 2/RI. Ideally, during turn-on RI should be very large, and after the supply is operating, should be reduced to zero. The NTC thermistor is ideally suited for this application. It limits surge current by functioning as a power resistor which drops from a high cold resistance to a low hot resistance when heated by the current flowing through it. Some of the factors to consider when designing NTC thermistor as an inrush current limiter are: 

The main purpose of limiting inrush current is to prevent components in series with the input to the DC/DC convertor from being damaged. Typically, inrush protection prevents nuisance blowing of fuses or breakers as well as welding of switch contacts. Since most thermistor materials are very nearly ohmic at any given temperature, the minimum no-load resistance of the thermistor is calculated by dividing the peak input voltage by the maximum permissible surge current in the power supply (Vpeak/Imax surge).