月：2015年10月

analogtechnologies.com

Common Failures and Causes for NTC Thermistor

NTC thermistor can be applied in many fields, such as temperature measurement and control, temperature compensation, surge current suppression, environmental measurement, etc.
There are some common failures and causes for NTC thermistor
1. Short circuit:
When theloop current is higher than Imax, or power rating is higher than Pmax for a long time, it will make the temperature of the thermistor higher than Tmax. At the start, the thermistor will have a rather low resistance, and then the thermistor will be burnt, resulting in short circuit or open circuit.
2. Open circuit/Damage:
When an instant huge energy is loaded in the thermistor, the product may not bear it and then damage. Generally, it shows high impedance or direct open circuit.
3. Offset resistance: NTC thermistor is the semiconductor component that is much sensitive to heat.　If the IR reflow and rework exceeds certain temperature and time, the thermistor can easily be damaged, resulting in offset resistance. The resistance can increase or decrease.
Physical photo of NTC thermistorwith ring lug
ATI provides various NTC thermistors with different nominal values and B values, which can meet requirements for the applications above.
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Advantages of Peltier Controller

Peltier controller is a kind of electronic module, which is designed and produced by Analog Technologies Inc. (ATI). There is a variety of Peltier controllers in ATI, such as TECA1-XV-XV-D series, ATFC105D series, ATW3A314 series and so on.
TECA1-XV-XV-D series Peltier controller has high efficiency, high stability, compact size and long service lifetime. ATFC105D series Peltier controller comes with a key pad and a digital display screen, which is used to drive TEC assemblies and monitor the working temperature at the same time.
Figure 1. The photos of TECA1-XV-XV-D and ATFC105D seriesPeltier controllers
ATW3A314 seriesPeltier controller is a product under development, which can stand by automatically when the object temperature is within a pre-set temperature window.It comes with Seebeck voltage available. This Peltier controller can switch frequency synchronizable to an external signal.
Figure 2. The physical photo of ATW3A314 seriesPeltier controller
There are many other Peltier controllers with high quality and exellent performances. You can choose what you need. In addition, we can also customize a specialized Peltier controller based on TEC controller.
If you want to know more about Peltier controller, please feel free to contact us.
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NTC Thermistor ATH10KL2B and ATH10KL2C

ATI provides a variety of basic NTC thermistor, such as ATH10KR8, ATH10K1R0, or ATH10K1R25. These NTC thermistors come with high stability and accuracy, which can be used for optical components, industrial fields that high precision temperature measurement and control is needed.
Based on these basic thermistors, ATI has developed updated products. Take ATH10K1R25 as an example. ATH10K1R25 is a glass encapsulated NTC thermistor with bare leads or leads covered with high temperature plastic tubing. The resistance accuracy is 1%. It comes with a compact size: φ1.25mm×2.0mm. The temperature range is −40°C to 270°C.
As a core of new products, ATH10KL2B and ATH10KL2C have ATH10K1R25 inside them as the thermistor head, while outside the thermistor, there is a ring lug, which is used for easy fixing. There is a difference between ATH10KL2B and ATH10KL2C even if they have a same thermistor head. They come with different ring hole diameter: it is2.18 ± 0.1mm for ATH10KL2B, and 3.02 ± 0.1mm for ATH10KL2C. The latter is larger than the former, which can meet different requirements.
Physical photo of NTC thermistorATH10KL2B and ATH10KL2C
These NTC thermistors have different nominal values and B values, which can meet different requirements on various thermal control applications.
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Practical Functions of NTC Thermistors

NTC thermistor in series in AC circuit functions like current insurance.
How does this insurance do in the circuit? When the circuit is powered on, there produces an instant surge current. Thermistors can suppress this current. After this, the current will keep stable, and then the NTC thermistor will decrease its resistance to an ignorable value, which will not influence the current.
During power-off at room temperature, the resistance of thermistors is relatively high, and at the moment of power-on, the resistance remains high, which is used to suppress the surge current. Then the temperature increases, and the resistance decreases to an ignorable value. If there is another surge current at this time, NTC thermistor cannot help and it needs a fuse. That is to say, NTC thermistor can only function at the moment of power-on. For the power supply that has a NTC thermistor inside, it cannot frequently power on and off. Restart only when the NTC thermistor cools down to its cold resistance. That means NTC cannot function when there is frequent power on and off.
Physical photo of NTC thermistor
ATI offers various NTC thermistors with high accuracy and reliability, such as ATH10KR8, ATH10KL2C, etc.
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Characteristics of Inductor Kits

The Inductor kit is a research and development product of ATI, which is utilized to store inductive elements. Inductor kits released by our company have high quality and long service lifetime. There are 128 individually lidded compartments, and inductor values are printed on each lid. In order to find inductors easily, the values are arranged in the order from left to right and from top to bottom. Each lid inside is very tight so that internal chip inductors can be ensured not to leak or lose. The following is the photo of an actual inductor kit.
Figure 1. The physical photo of an actual inductor kit
Inductors are 100% lead (Pb)-free and RoHS compliant. According to the size, the inductors are divided into four series, 0402 series, 0603 series, 0805 series and 1008 series.The appearance size of an inductor kit is 11” (L) * 8.5” (W) (the letter paper size) *1.75” (H). Thus it is very convenient to carry and display.
Besides inductor kits, there are also resistor kits, capacitor kits and empty enclosuresin our company.
If you want to know more about inductor kits or other related products, please feel free to contact us.
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Application Examples of NTC Thermistors (IV)

6. The function in power supply circuit of NTC thermistor 
NTC thermistors in series in the AC circuit plays a role of “current insurance”. NTC thermistors in parallel in the AC circuit plays a role of “limit overvoltage”. Frequent on/off is not allowed when using NTC thermistor in the power supply for startup surge suppression. Restarting is allowed when NTC thermistor cooled down to a cold resistance. Otherwise, NTC thermistor in the circuit will have little effect.
7. NTC thermistor in medical electronic thermometer
Nowadays, many large hospitals use electronic thermometer, which has a short measurement time, a high accuracy, and a memory function. It’s also easy to read. It performs well in clinical use. There are four components in the thermometer, heat detector, signal processing unit, display and power supply. Heat detector is a sensitive component, which generally applies one or more high accuracy fast response NTC thermistors. This is closely related to the accuracy and response speed of output temperature; signal processing unit has two algorithms, heating and calculating.
Physical photo of NTC thermistor
ATI offers various NTC thermistors with and without ring lug, such as ATH100KR8, ATH100KL2C, etc.
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Application Examples of NTC Thermistors (III)

4. NTC thermistor “temporary” insert sensor
This type of thermistor sensor can insert into human body through an incision (the typical way is through a catheter). Compared with implantable sensor, this insert sensor has less danger. According to different surgeries, this sensor can effect for a few minutes to a few hours. Ideally, these sensors don’t need external force to drive, but if necessary, it can be driven by external forces.
5. NTC thermistor water temperature and water level sensor for solar heater
The thermistor sensor is a device that can sense the water temperature and water level, and then transform them into changing electronic signal. In the development history of solar heater, water temperature and water level sensor has played a vital role. The intelligentialization and humanization of the heater is inseparable to the water temperature and water level sensor, so is water temperature and water level measuring instrument. This sensor’s working status is a guarantee of the intelligent control of the whole heater.
To be continued…
Physical photo of NTC thermistor
ATI offers various NTC thermistors with and without ring lug, such as ATH100KR8, ATH100KL2C, etc.
analogtechnologies.com

Application Examples of NTC Thermistors (II)

2. NTC thermistor medical implantable sensor
Implantable sensor requires a compact size, light weight and body compatible. It should have a very small power. The most important, the thermistor cannot decay over time. Generally, this kind of thermistor sensor is very expensive and needs medical experts to do surgery for transplanting.
3. External sensor for NTC thermistor and body fluid contact
There are some types of disposable sensor that are used extra corporally, but they contact the body liquid, such as disposable blood pressure sensor. This kind of sensor is used for surgical and intensive care, which can continually monitor the pressure of the patients. This is the most ideal method to measure blood pressure when the patients is under IV. This type of thermistor sensor needs to be replaced per 24 hours in order to ensure the cleanliness of the sensor. The sensor is connected to a monitor to record all the information. There are some other types of thermistor sensor contacting with body liquid.
To be continued…
Physical photo of NTC thermistor
ATI offers various NTC thermistors with and without ring lug, such as ATH100KR8, ATH100KL2C, etc.
analogtechnologies.com

Application Examples of NTC Thermistors (I)

NTC thermistor plays a vital role in many applications, due to its characteristics: the resistance decreases with the increase of the temperature and the resistance increases when the temperature falls. There are some application examples of NTC thermistor.
1. NTC thermistor in body temperature probe
The temperature accuracy of body temperature probe can reach 0.1°C. Therefore, the requirements on the thermistor is compact size, high accuracy, high reliability, good thermal cycle resistance capability. Clinical monitor applies double track body temperature measurement circuit, which is used for monitoring critically ill patients. It requires that one body temperature probe provides double track temperature measurement, which can match the double track temperature measurement circuit in the monitor. Traditionally, put two NTC thermistors in parallel to form a body temperature probe. Since this kind of probe has a large size, which cannot meet the requirements of miniaturization. On the one hand, two thermistors make the measurement result more accurate, for the reason that we can compare the results of two chips, and we can get a more accurate actual temperature. On the other hand, it has higher reliability. When accidentally one chip has sudden failure, the other chip can work well.
To be continued…
Physical photo of NTC thermistor
ATI offers various NTC thermistors with and without ring lug, such as ATH100KR8, ATH100KL2C, etc.
analogtechnologies.com

Applications of NTC Thermistor ATH10KL2A

ATH10KL2A is a kind of NTC thermistor, which is packaged with glass.The resistance value of NTC thermistor ATH10KL2Ais 10K at the temperature of 25°C. This NTC thermistor comes with an extra small ring lug for being fixed easily. As NTC thermistor ATH10KL2A has compact size, short respond time and some other good characteristics, it has been widely utilized to measure the temperature of laser diode, optical elements, etc.,with high accuracy and long term stability. Figure 1 is the physical photo of a NTC thermistor ATH10KL2A.
Figure 1. The physical photo of a NTC thermistor ATH10KL2A
The NTC thermistor ATH10KL2A is made of three versions, ATH10KL2A, ATH10KL2AT63 and ATH10KL2AT63S. There are some differences among them. The first NTC thermistor comes with bear leads coated with copper, the leads of the second one is covered by using high temperature plastic tubing and the last one has two sealed leads.
This NTC thermistor can be mounted on a smooth metal surfaceof an object for which the temperature needs to be measured by using M2.5 metric screw. In order to obtain an accurate measurement result, a cover made of thethermal insulating materialshould be used to cover the NTC thermistor area.
If you want to know more about NTC thermistor, please contact us.