The working principle of CNC switching power supply
A non-volatile CNC potentiometer is selected as the controllable device for the PWM chip comparison reference voltage, which has low power consumption, easy to use and good reliability. It is a resistor array containing 31 resistor cells with tap points for sliding cells to access at the end points between each cell. The position of the sliding unit is controlled by three inputs, CS.U/D and INC, and the position of the sliding end is stored in a non-volatile memory which can be recalled at the next power-up operation.
The output voltage range of the switching power supply is determined by VL and VH. The formula for the output voltage shows that as long as the consistency of VL and VH is ensured, the consistency of the power supply output voltage can be ensured. Assuming that the voltage regulation range is 4.5V~5.2V, then the output voltage deviation is ±20mV, which can fully meet the power supply requirements of LED. In order to improve the anti-interference performance, the digital signal into the switching power supply optical isolation.
The use of CNC switching power supply
CNC switching power supply signal generator is composed of a microcontroller signal processing system, as shown in Figure 4. It stores the voltage value that should be output under different temperatures to compensate for LED temperature drift, as well as the output voltage value determined by the brightness of the LED display under different light conditions. The CNC switching power supply has three control modes: automatic, manual and programme.
1) Automatic control
Temperature sensor and light sensor regularly collect the temperature and light intensity of the site and send them to the signal generator for data processing. The control signal corresponding to the exact position in the 32 files of the CNC potentiometer is generated and amplified by the signal driver split to meet the demand for signal transmission of the m×n switching power supply. After receiving the CNC signal, the CNC switching power supply adjusts the output voltage and then sends it to the LED display.
2) Manual control
Use the keyboard of the signal generator to input a certain value, which is processed by the signal generator to produce a digital control signal, which is amplified by the driver and sent to each CNC switching power supply to output different voltages to be sent to the LED display.
3) Programme control
By the broadcasting machine through the serial interface to send commands, sent to the signal generator, processed to produce control signals, amplified by the driver, and sent to the numerical control switching power supply, the output of different voltages sent to the LED display.
The special switching power supply for outdoor full-colour LED display has been widely used in many outdoor full-colour screens. The use situation is satisfactory. With the continuous development of outdoor full-colour LED display technology, switching power supply has to be further developed to meet the various requirements of full-colour screen.
