Quote:
Originally Posted by MPaulHolmes
I can easily adjust the values and mail you a new chip if it comes to that, like if it turns on too soon. Right now, I have it start to limit max current when the internal heatspreader hits 75 degC, and there is complete thermal shutdown at 85 degC (internal heat spreader temp).
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This might be appropriate though for keeping the diodes/mosfets from getting too hot. You're still using the thermal pad to isolate all the components, correct? There could be a large temperature drop across that pad, especially if there's a lot of heat generation and the heat spreader (and thermistor) haven't had time to heat up. The silicon could be much hotter and having lots of margin might be desirable. (I'm having trouble with my charger design getting hot and blowing FETs. Those high voltage FETs aren't as efficient!)
If it happens that thermal shutdown occurs, it might be better to try to reduce the thermal resistance to keep things cooler rather than adjust the threshold higher.
Guess we can cross that bridge if it comes up - maybe everything will work fine and we won't have a problem! 120F is 49C - That leaves 26C above ambient for a controller that's gotta be more efficient than the Curtis.