Digital Potentiometer (POT) to Control LED Brightness APPLICATION NOTE
●Light-emitting diodes (LEDs) require a regulated current,and their brightness is proportional to the current that flows through them. Some LED drivers use an external resistor to set the LED current. A digital POT can replace a discrete resistor with the advantage of providing an adjustable value allowing the LED brightness to dynamically change. Most digital POT circuits have the ability to store permanently the resistor value in non-volatile memory.
●This application brief shows a digital POT circuit used in combination with the CAT32 white LED driver. The digital POT is connected as a 2-terminal variable resistor, as shown in Figure 1. The potentiometer Wiper-to-Low resistor(between W and L pins) is connected in series with the RSET resistor to adjust the LED brightness. This example uses a 100-tap linear potentiometer, the CAT5113, with an end-to-end resistance of 50 kΩ. The wiper terminal (W)position is controlled through a 3-wire interface. The INC input increments the wiper in the direction which is determined by the logic state of the Up/Down input. The CS input is used to select the device and also store the wiper position prior to power down.
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Application note & Design Guide |
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Please see the document for details |
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English Chinese Chinese and English Japanese |
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April, 2019 |
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Rev. 2 |
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AND8412/D |
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132 KB |
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