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How to choose a stable power supply for high and low temperature test chambers?

In order to input the signal of the high and low temperature test chamber into the A/D converter stably, a stable power supply is required. Constant current is the basis for providing stable current for other circuits, so as to ensure their stable operation. Therefore, a stable constant current source must be designed.

　　 For the design of this high and low temperature test box, TL431 was selected as the 2.5V constant current source selection device. TL431 is a three-terminal adjustable shunt reference with good thermal stability. In the range of 2.5~36V, the output voltage can be set by two resistors to set any reference source. Its dynamic impedance is typically 0.2Ω, which has replaced Zener diodes in many applications. TL431 is a parallel integrated voltage regulator. Because of its low price and good performance, it is widely used in various power circuits.

The main parameters of TL431: The output voltage of the three-terminal adjustable shunt reference power supply is 2.5~36V; the typical value of the low dynamic output impedance is 0.22Ω; the voltage reference error range is ±0.4%; the temperature compensation operation is fully rated Temperature range; the typical value of temperature compensation operation is 0.22 ohm; the temperature characteristic of the equivalent full range is ±0.4%; the full rated value of temperature compensation operation is ±1%; the typical value is 0.22 ohm; output The current is 1.0~100mA; the temperature characteristic is flat, it is usually 50ppm, and the output is low voltage noise; the maximum input voltage is 37V, the working current is 150mA, the internal reference voltage is 2.5V, and the output voltage is in the range of 2.5-36V.

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