Analog-to-digital conversion and voltage stabilization circuit diagram

D/A conversion is mainly achieved using the MAX522 chip.

The MAX522 chip has two 8-bit voltage buffer output D/A converters (DAC A and DAC B), 8-pin saving package and DIP package, DAC A end buffer working current can reach 5mA, DAC B end buffer working current can reach 500μA, MAX522 works in a unidirectional voltage of +2.7V~+5.5V.

MAX522 has a 3-wire serial interface that is directly compatible with SPITM, QSPITM, and MicrowireTM. It has a 16-bit input shift register that contains 8-bit DAC input data and 8-bit DAC selection and shutdown control. Data can be stored in the DAC register on the positive edge of /CS.

The analog-to-digital conversion module circuit is shown in the figure. The PB0 port of the microcontroller is connected to the serial data input port DIN, PB1 is connected to the chip select signal /cs, and the PB2 port is connected to the clock signal SCLK. Select DAC A as the output, and connect a 0.1μF capacitor to the output and reference voltage input terminals respectively to improve the output stability of the circuit. The VDD and reference voltage terminals of the chip are both provided by a 5.12V voltage regulator circuit.

Figure analog-to-digital conversion and voltage stabilization circuit

The LM336 integrated circuit is a precision 5V voltage regulator, which works as a 5V Zener diode with a low temperature coefficient and a dynamic resistance of 0.2Ω. The fine-tuning terminal (G) can fine-tune the reference voltage and temperature coefficient. The output voltage of the LM336 is adjusted to 5.12V by adjusting the adjustable resistor. Therefore, the resolution of the MAX522 output voltage is 5.12/256=0.02V, which means that the voltage increases by 0.02V for every increase of 1 in the MAX522 digital input. Since the power supply output voltage range is 0~12V and the step accuracy is 0.1V, the maximum input data is 120 (the binary value is 11110000), and the MAX522 output value is 2.4V. That is, the output voltage of the MAX522 changes from 0 to 2.4V.