Adjusting LED current by adjusting control voltage...how?

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treez

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Hello,

The HV9910B allows you to adjust the LED current by adjusting the voltage into the "LD" pin.

The range of the "LD" pin voltage is from 0 to 250mV.

...this is very low voltage, how could you accurately apply control voltages of 50mV, 100mV, & 200mV to the "LD" pin?
 

If you use microcontroller, then a digital to analog converter can do this....
DAC can also be used without microcontroller, you have to configure the digital input manually.

Have a look at this...
**broken link removed**
 
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Thanks, but i cannot afford a DAC, so i wish to put a 250mV voltage across the internal resistor of this digital pot, and then use the digital pot to divide down this 250mV voltage

digital pot = MCP4011....
https://ww1.microchip.com/downloads/en/DeviceDoc/21978c.pdf

......the problem is that the resistor in the digital pot is 2K1, and so i am going to have just 125uA flowing in the resistor, so do you think the control voltage will succumb to noise?
 

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