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# Is AN19fc available for LT8709 ?

Hi

I consider using LT8709 for negative inverting converter as -48V to +12V, 3A. But I don't understand the equations in table 2 on LT8709 data sheet. Because I don't understand what the parameters mean as follows. There are 0.58, 0.05 and 1.6 in the Rsense equation, there are 12.5mV, 40mV and 3mV in the L calculation. So I'll try to calculate following AN19fc below link. What do you think abut that ?

https://www.analog.com/media/en/technical-documentation/application-notes/an19fc.pdf

Regards,

Hiroyuki

• I think that is better to use LT8709 datasheet formulas. The 0.58 is a coefficient, the 0.05 is in Volts. Use physical UNIT LESS, just the values, numbers to calculate Ltyp, Lmin, Lmax.  The 12.5mV  is 12.5E-3 , 40mV is 40E-3 and 5mV is 5E-3.

• Dear Victor,

Thank you very much for your support. Regarding (2) formula of Step 6, 2DCmax-1 would be always minus value because DCmax is lower than 1. Then the Lmin value would be also minus. I'll take a look datasheet for detail.

Regards,

Hiroyuki