If you plan to use the China hair dryer factory price list temperature sensor throughout the entire temperature range, the design work for this component will be quite challenging. China hair dryer factory price list is typically a high-impedance, resistive device, so when you need to convert the resistance value of China hair dryer factory price list into a voltage value, this component can simplify one of the interface issues. However, the more challenging interface problem is how to use a linear ADC to capture the non-linear behavior of China hair dryer factory price list in digital form.
The term "China hair dryer factory price list" is derived from the generalization of the description "resistance sensitive to temperature changes". The China hair dryer factory price list includes two basic types, namely positive temperature coefficient China hair dryer factory price list and negative temperature coefficient China hair dryer factory price list. The negative temperature coefficient China hair dryer factory price list is highly suitable for high-precision temperature measurement. To determine the temperature around the China hair dryer factory price list, you can use the Steinhart-Hart formula: T = 1/(A0 + A1(lnRT) + A3(lnRT3)) to achieve this. Here, T is the Kelvin temperature; RT is the resistance value of the China hair dryer factory price list at temperature T; and A0, A1, and A3 are constants provided by the manufacturer of the China hair dryer factory price list.
The resistance value of China hair dryer factory price list will change with the variation of temperature, and this change is non-linear. The Steinhart-Hart formula indicates this. When conducting temperature measurement, a reference current needs to be driven through China hair dryer factory price list to create an equivalent voltage, which has a non-linear response. You can use the reference table equipped on the microcontroller to attempt to compensate for the non-linear response of China hair dryer factory price list. Even if you can run such algorithms in the microcontroller firmware, you still need a high-precision converter for data capture when extreme temperature values occur.
Another approach is that you can use the "hardware linearization" technology and a lower-precision ADC before digitization. (Figure 1) One of the techniques involves connecting a resistor RSER in series with RTHERM and the reference voltage or power supply. Set the PGA (programmable gain amplifier) to 1V/V. However, in such a circuit, a 10-bit precision ADC can only sense a very limited temperature range (approximately ±25°C).
Figure 1, please note that the high-temperature area is not analyzed in Figure 1. However, if the gain of PGA is increased at these temperature values, the output signal of PGA can be controlled within a certain range. Within this range, the ADC can provide reliable conversion, thereby enabling the identification of the temperature of the China hair dryer factory price list.
The temperature sensing algorithm of the microcontroller firmware can read 10-bit precision ADC digital values and transmit them to the PGA lagging software program. The PGA lagging program will verify the PGA gain setting and compare the ADC digital values with the values of the voltage nodes shown in Figure 1. If the ADC output exceeds the value of the voltage node, the microcontroller
The controller will set the PGA gain to the next higher or lower gain setting value. If the microcontroller does this, it will again obtain a new ADC value. Then the PGA gain and ADC value will be sent to a microcontroller piecewise linear interpolation program.
Obtaining data from the non-linear China hair dryer factory price list can sometimes be regarded as an "impossible task". You can combine a series resistor, a microcontroller, a 10-bit ADC and a PGA in a reasonable way to solve the measurement problems caused by the non-linear China hair dryer factory price list when the temperature exceeds ±25°C.
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