Hi team,
Another question about TPS92691EVM-001
1.When using the recommend PWM input for dimming , I found the output current has a surge current on the rising edge of the PWM input voltage. The maximum of the overshoot can reach up to 1.1A at pulse current= 300mA. I tried changing the output voltage 7.5V~35V, PWM duty cycle and frequency, and changing the voltage of IADJ pin, but the overshoot remained high. The GATE waveform seems no problem. But the Q2 drain peak voltage value changes with the output current, while duty cycle is constant.
Green: output current
By the way, is Q2 drain voltage the Switch Node of this SEPIC?
2.In datasheet figure 27 BUCK LED DRIVER, I found Vin pin connects to diode cathode. The VIN and ground connection seems opposite of the normal BUCK topology (this picture). I derived formula is still Vout=Vin * D, but I don't understand why to do this?
