Tool/software: WEBENCH® Design Tools
Hi,
LM5175 Vin6-34V; Vout 12V@2A:
Due to wrong placement of Cc1 and Cc2 (values from these capacitors exchanged in BOM) we get calculated with Webbench Tool an instable phase margin.
(Cc1=68pF, Cc2=56nF). But in real life there is no instability in load situation.
What we have seen is with no/light load and higher Vin (24V-34V) a saw tooth looking Vout 12V+-1.5V (the reason why we searched for mistakes). But with corrected compensation (Cc1, Cc2 values) the behaviour is not improved at no/light load.
When the sawtooth looking Vout is visible, the constant on FET from the boost side is switching with very short duty cycle.
Please give us advice why compensation is not relevant as expected and what can cause the no load saw tooth looking Vout.
What is the worst case cenario for wrong compensation network?
br, MSPUser
