Should SEPIC inductors be sized according to the average load current or the peak load current?
For instance my load draws one amp pulses (3uS PW) but at ten percent duty so this is an average of 100Ma. Should the inductors be sized for
Would I be better of designing for DCM or CCM?
Thanks
The switcher loop won't react much in 3 us, so you're going to have to depend on the output capacitor to supply the load current, and the switcher basically recharges it between shots. So, size L for the average, or maybe a bit above, 200 mA maybe.
At 10 mA, it will almost certainly go discontinuous. You may as well keep it discontinuous at max load, to keep the loop dynamics relatively constant, but if it transitions tio continuous at some intermediate load, that's usually OK.
John
Thanks John
John is right above relative to the load current which mainly comes from the capacitor. However, you really have to ask the question based on the current in the inductor, not the load for which you need the duty cycle. At 50% this current would be 200mA.
The inductor must be sized for the PEAK current in IT for all conditions of line, load and duty cycle. The inductor current determines the saturation of the core which under normal operation should be avoided.
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