LM3402: PWM dimming frequency range

Hello,

3.3V PWM signal is fine, in the datasheet:

"7.3.7 Fast Shutdown for PWM Dimming
The DIM pin of the LM3402/HV is a TTL logic compatible input for low-frequency PWM dimming of the LED. A
logic low (less than 0.8V) at DIM will disable the internal MOSFET and shut off the current flow to the LED array.
While the DIM pin is in a logic low state the support circuitry (driver, bandgap, VCC) remains active to minimize
the time needed to turn the LED array back on when the DIM pin sees a logic high (above 2.2 V). A 75 μA
(typical) pullup current ensures that the LM3402/HV is on when DIM pin is open circuited, eliminating the need
for a pullup resistor. Dimming frequency, fDIM, and duty cycle, DDIM, are limited by the LED current rise time and
fall time and the delay from activation of the DIM pin to the response of the internal power MOSFET. In general,
fDIM should be at least one order of magnitude lower than the steady state switching frequency to prevent
aliasing."

The PWM dimming range is based on your design, your operating frequency, input and output voltage as well as output current and output capacitor.

Best Regards,