CH452 application circuit design
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In the figure, the single-chip U2 drives 8 common cathode digital tubes through the CH452 and simultaneously scans 64 buttons. Because some digital tubes have reverse leakage at higher operating voltages, it is easy for CH452 to mistakenly think that a button has been pressed all the time. Therefore, it is strongly recommended to use diodes D1-D8 to prevent digital tube reverse leakage and improve the keyboard. The level of the SEG0~SEG7 input signal during scanning ensures that the keyboard scan is more reliable. When the supply voltage is low (eg VCC = 3.3V), these diodes should be removed to avoid affecting the display brightness.
If the CH452S chip uses both keyboard scanning and digital tube display functions at 5V, then a diode must be added.
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