Hi,
My customer has the following questions:
We use an L55281 LED Driver to generate a 4.0V output with an input that can range from 3.4V to 4.35V. I had some questions about this.
1. For voltages above 4V I understand that the regulator PWM falls to 0% duty and current flows through the diode. Thus, at no load conditions, Vout is mostly equal to Vin and as current starts to flow, Vout will be a diode drop below Vin. This is my understanding – so please correct me if I’m wrong.
2. Our firmware does not set the EN_AUTOLOAD bit. I’m somewhat confused from reading the datasheet, but if this bit isn’t set does that mean we operate in a pulse-skipping mode from 3.5V to 4V? We use an 82k for IRT and we are switching at 2MHz.
3. Do you have a document that describes how pulse skipping works? I am trying to understand how operating in this mode would affect a frequency domain stability measurement of gain and phase margins.
Thanks,
Chuchen
