Author Options:

calculating MAX7219 resistor value? Answered

I want to use the 7219 to drive two 3digit 7segment displays with these specs. I want to use 1.85v and 18mA.

Here's what the MAX7219 datasheet states as resistor values to be used.

I'm too dumb to figure out how the resistor value is calculated. Can someone help? What would the resistor value be for 1.85v 18mA?



Try 33K. The value is allegedly calculated roughly by 200X (supply volts- led volts)/LED current. Table 11 says one thing, the text says another. Try the 33K first. Try 18K if it isn't bright enough.