# POWER STAGE CALCULATIONS

Please refer to the LT16810 datasheet for many of these calculations.

## Contents

- Some Constants
- FB Resistor Network
- Inductor Selection
- Max Frequency of Switching

## Some Constants

    Vin = 15; %volts
    Vout = [3.3 5];%volts

## FB Resistor Network

Referring to scott's original circuit, we have to reset the value of the divider.

Originally it was:

    R1 = [620e3 866e3];
    R2 = [243e3 200e3];
    VoutOrig = (R1./R2+1)*0.970

    % Let's reset for 3.3 and 5. Let's keep R2
    R1new = [1e6 1e6];
    R2new = [412e3 243e3];
    VoutNew = (R1new./R2new+1)*0.970

    % Determine the quiescent current
    Iq = (1.7e-6 + (VoutNew/(R1new+R2new))*(VoutNew/Vin)*(1/.8) ) * 1e6 %uA

    VoutOrig =

        3.4449    5.1701

    VoutNew =

        3.3244    4.9618

    Iq =

        2.5503    2.9691

## Inductor Selection

This a simple suggestion for where to start based on sampling frequency

    fsw = 0.200; %MHz
    Vout
    L = (Vout + Vswbot)/fsw

    Vout =

        3.3000    5.0000

    L =

       17.2500   25.7500

## Max Frequency of Switching

    % First some supporting variables.
    Vswbot = 0.15;
    Vswtop = 0.3;
    tonmin = 45e-9;
    fswmax = Vout;

    %The resulting operating frequencies (MHz) are

    fswmax = ( Vout + Vswbot) ./ (tonmin * (Vin - Vswtop + Vswbot))*1e-6

    %

    fswmax =

        5.1627    7.7067