Hello,
I have an application that needs Vin=12V-16.8V, Vout=12V, Iout=4.5A.
Of course it is not possible to have 12Vout when Vin approaches 12V, unless the part supports 100% duty cycle.
However, it is not essential in our application for the output to be a perfect 12V; some output sag at low input voltage is acceptable (-7.5%)
It appears this part has a maximum duty cycle of 98%, so doing some quick math I think the output voltage sag would be:
- (DC%) * (Vin - I*R)
- DC%=0.98
- Vin=12V
- I=4.5A
- R=57m + 25m (FET + Ldcr)
- Vout = ~11.4V
This ignores the 2% part of the switching cycle, but I think that's okay for this approximation.
- Do you think 11.4Vout is realistic?
- Will the part still behave normally when operating in "drop out" like this?
- Is there a better part to consider? Cost is priority, efficiency a close second.
Thank you!
