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ailex

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  1. Circuit Diagram is given below: The circuit diagram of a three channel LED driver circuit using MAX7219 is shown below (Fig 1). C4 is an input filter capacitor. R1 is the resistor used for programming the output current. C3 is the output filter capacitor. C1 and C2 are the storage capacitors of the internal charge pump circuit. A logic high at pin 5 will enable the IC and a logic low on the same pin will drive the IC into shutdown mode. In the shutdown mode, the quiescent current is almost equal to zero. With the used value of R1, the LED current per channel will be 25mA. When powered up the MAX7219 operates in 1X mode i.e, the output voltage will be equal to the input voltage. If this output voltage is enough to regulate the current through all LEDs, the IC remains 1X mode. If the output voltage is not sufficient enough to regulate the desired current through the LEDs, the device automatically switches to the 1.5X mode where the output voltage is 1.5 times the input voltage. This process is repeated when ever the IC is powered up or awaken from shutdown mode. Can this circuit work? Actually,the LED driver in this circuit is CAT3063,however,I can't found this mode. I would like to use MAX7219 instead of CAT3063. Please give me some help! Appreciating!
  2. Good afternoon~all Please help me out. As the LP3856’s datasheet shows,the inputted current is 3.3V,the outputted current is 1.8V,the referring voltage is 1.216V,. What should I consider about when in the design process? Can I use LP3856 here ? Wishes~
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