hi ,
do you need to put a resistor in series with a string of leds when using a led current driver.
if so how do you calculate the resistance with a variable voltage.
thank
mark
No, if you've got a constant-current source, you don't need current-limiting resistors
thanks for your help .
much appreciated.
The constant current source will work nicely but it has some headroom (voltage drop). It also has another minor problem, the Leds will extinguish when the variable voltage drops below the sum of the Vf of the LEDs in the series string. You might consider posting a simple schematic if you have problems.
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