Other Parts Discussed in Thread: LM5155, LM5158
There are few points I couldn't understand about current sense functionality in LM3478.
The option to set current limit by choosing Rsn works like if voltage across Rsn (which is given as input to Isn) crosses threshold (~190mV), the MOSFET will be turned off till the next cycle.
The short circuit sensing happens if there is ~300+ mV at Isn pin.But when will this happen? As soon as the pin voltage reaches 190mV, the MOSFET is turned OFF right?
And I couldn't completely understand the plot attached with this post. The duty cycle is set using feedback resistors right? If no load is connected and current ripple is small, then current through MOSFET will be low. If it is low enough to make current sense voltage less than 0.1V, does the duty cycle reach 100%? If so, how is the output voltage set to desired value?
Chiranjeevi M R