Ubergeek63
Well-Known Member
You do not adjust the PWM, the 9910 adjusts in order to regulate the current.
You can put in a voltage on the LD (linear dimming- it is meant to drive power LEDs) pin to bring the peak voltage on the current sense down from 0.25V.
When the frequency adjust resistor is tied to the drive pin instead of ground it works in constant off time mode. In this mode the frequency varies as the line and load vary to maintain a constant current output.
You can put in a voltage on the LD (linear dimming- it is meant to drive power LEDs) pin to bring the peak voltage on the current sense down from 0.25V.
When the frequency adjust resistor is tied to the drive pin instead of ground it works in constant off time mode. In this mode the frequency varies as the line and load vary to maintain a constant current output.