LTC3114-1 Secondary Foldback Current Limit

Question

Hi, Guys. 
 Thank you for your support. 
 
 I have some question about the secondary foldback current limit (Datasheet page12). 
 Q1: Is it the characteristic of the foldback function that a graph of "Avarage Output Current vs Vout" on datasheets page6 ? 
 Q2: If Q1 is Yes, is the characteristic the same even if the value of Rprog is changed? 
 Q3: Is the characteristics also the same at a startup cycle? 
 
 I tried to check using LTspice, but I can't understand it.

LT3114-1_CCCV-2.asc LT3114-1_CCCV-2.asc 
 
 Best regards, 
 Yuki.

ADIApproved · Accepted Answer

Hi, 
 The waveform on page 6 of the datasheet is an example of programable output current limit across Vout range for a given Rprog .The output current limit changes and so does the characteristic curve will vary with Rprog. However for Vout below 2V the current limit will not be proportional to Rprog. In the simulation, I think the load is set higher than the current limit so the Vout starts to drop after startup. 
 Thanks)

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LTC3114-1 Secondary Foldback Current Limit