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Hi FORUM.
I am now working on a DC-DC converter using the 38085 but there are a couple of things in the Data sheet which are not very clear to me.
The value of this resistor is found from the Formula on the image.
I'm not too clear on how to derive :RAMP VOLTAGE HEIGHT" ?
Is this the peak voltage developed across the current sense resistor? or something else.
Thanks
Julian
Hi Teng
so, in regard to Equation 2 and the meaning of RAMP VOLTAGE HEIGHT, is this derived from multiplying the current limit value set by 5 ?
Otherwise, how do we actually establish a real world number for that value?
Thanks
J
Hi Teng
I do 'get' why slope compensation is needed, I simply could not find a real value in the data book that I could plug into the formula to make get a value of Rset.
I love it when engineers go through 3 pages of maths and then say "In the end.. we resort to the 'empirical' method" :) i.e.. suck and see.. trial and error etc...
So your 'gotten from debugging' seemed in that category...but I totally am ok with that.. I just needed the guidance to push me in the right direction.
cheers
Julian
Hi Julian,
Practically, you can first set slope compensation voltage height 20% of maximum current sense resistor voltage height, on the basis of which, then regulate the compensation slope to ensure elimination of sub-harmonic oscillation. Thanks.
Regards,
Teng