Other Parts Discussed in Thread: LM5141
I am looking to use the LM5085 in an application where the current limit runaway is a real concern. I have a relatively large bulk capacitor on the LM5085 output (which will look like a short circuit until it is charged) and also the risk of an actual short circuit on the output. I have gone through datasheet section 7.3.5 - Current Limit Off-Time. For my 30V input I get a required Vfd + Vesd of about 300mV. This was using the nominal values for Ton_min and Toff_min.
Does this result seem correct? This seems easy enough to meet, as the diode Vf is at least 400mV. I do see the note that mentions that variations in t_on and t_off tend to move together. I assume this means that I do not need to worry about a minimum t_on and maximum t_off, which would give me a much higher requred Vfd + Vesd of about 800mV.
I guess the question comes down to - how common is it to have trouble with current runaway for this part? And if it is a real concern, what steps might you recommend to make sure it cannot happen in actual usage?