ニュース

1. What are the operating temperatures of temperature sensors using different core components?

Answer: (1) Welded bare chip or MF52A, MF51E, MF55: temperature resistance level 125℃, actual temperature resistance 150℃.

(2) Double-ended glass seal (MF58): temperature resistance level 200℃, actual temperature resistance 250℃.

(3) Single-ended glass seal (MF51): temperature resistance level 200℃, actual temperature resistance 250℃.

(4) Single-ended glass seal special model (MF51): temperature resistance level 250℃, actual temperature resistance 300℃.

(5) Non-welded chip: temperature resistance level 450℃, actual temperature resistance 500℃.

2. What are the design considerations and steps of temperature sensors?

Answer: (1) Select the appearance according to the customer's design requirements or installation requirements.

(2) Select core components and other materials with appropriate operating temperature range according to customer requirements or usage requirements.

(3) Select appropriate resistance value, B value and accuracy.

(4) Select appropriate moisture-proof insulation technology to meet the different needs of customers.

(5) Select appropriate packaging structure to meet the product's mechanical impact resistance.

(6) Meet customers' special requirements.

3. What are the main applications of NTC thermistors and PTC thermistors?

Answer: The resistance of NTC thermistors can decrease with the increase of temperature. Due to its very large temperature coefficient, it can detect small temperature changes. Therefore, it is widely used in temperature measurement, circuit soft start, control and compensation. Conventional thermistor temperature sensors are made of NTC thermistors.

The resistance of PTC thermistors can increase with the increase of temperature. Due to its very large temperature coefficient, it is mainly used in demagnetization circuits, heaters, circuit protection, motor start, air heaters, wind speed measurement, temperature control and compensation.

4. Can the resistance of NTC thermistors be measured with a multimeter?

Answer: When using thermistors, several important parameters must be tested. Generally speaking, thermistors are highly sensitive to temperature, so it is not suitable to use a multimeter to measure their resistance. This is because the working current of the multimeter is relatively large, and when it flows through the thermistor, it will generate heat and change the resistance value. However, a multimeter can also be used to make a simple judgment to confirm whether the thermistor can work.

5. In what areas are NTC thermistors widely used?

Answer: Negative temperature coefficient NTC thermistors are widely used in many industries such as home appliances (air conditioners, refrigerators, water heaters, etc.), automobiles, medical care, aviation, instrumentation, building automation control (HVAC, fire alarm), etc., and have broad market prospects. With the intensification of market competition and the improvement of product technology, the trend of using NTC thermistors in various home appliances has gradually increased. In addition, NTC thermistors have also been widely used in mobile phone crystal oscillators and rechargeable batteries, LCDs, PDAs, integrated circuits, overcurrent protection, etc. The delay effect of NTC thermistors can be used for surge current suppression, and they are widely used in various power supply circuits.

6. What are the main functions, characteristics and application range of SMD chip thermistors?

Answer: Function: high precision, no leads, small size, excellent solderability, and high stability. Features: Multilayer structure allows different resistance values ​​in the same B constant; ultra-small size, low capacitance, high B value; glass coating for long-term reliability; non-polarized for installation; suitable for wave soldering and reflow soldering.

Application range: temperature compensation of crystal oscillators (TCXO); temperature compensation of personal computers; temperature detection of CPU and storage devices; temperature detection of battery packs; temperature compensation of LCD contrast; temperature compensation and sensing of car audio equipment (CD, MD, tuner).

7. What material are NTC thermistor electrodes made of?

Answer: Thermistors can only be used normally in circuits if electrodes are added to the substrate, and changes in ambient temperature are measured by changes in thermistor resistance. It can be seen that in thermistors, electrodes play an extremely important role. At present, the materials used to prepare NTC thermistor electrodes are mostly precious metal materials, such as Ag, Ag-Pa, Au, Pt, etc. (the working temperature is very high, such as around 1000℃, platinum paste can be considered); when preparing NTC thermistor electrodes, domestic manufacturers generally use silver paste to prepare electrodes, and sometimes use Ag-Pa paste; some foreign companies use gold paste as electrode material.

8. What are the main temperature measurement methods used by NTC thermistors?

Answer: (1) Bridge measurement. Place the NTC thermistor in the environment to be measured, and use the NTC thermistor as a bridge arm of the Wheatstone bridge. Changes in ambient temperature will cause changes in the resistance of the NTC thermistor. The change in resistance can be known through the milliammeter. Using the characteristic that the resistance of the NTC thermistor changes with temperature, the temperature signal can be provided by measuring its resistance. With the corresponding circuit, temperature measurement, temperature display and temperature control can be performed.

(2) Single-chip microcomputer measurement. Usually, a precision resistor is connected in series with the NTC. The change in the NTC resistance value is converted into a voltage change and directly enters the A/D input interface of the single-chip computer without amplification. The circuit structure is extremely simple. As long as the resistance value of the corresponding NTC thermistor is measured, the temperature value can be obtained through calculation according to the resistance-temperature characteristics of the NTC thermistor.