User manual

Design Calculations

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14.4 Inductor

Calculate peak inductor currents at the minimum and maximum peak input voltages:

(36)

Calculate inductor ripple currents at the minimum and maximum peak input voltages based on 80% of

maximum peak inductor currents:

(37)

Verify that converter is in CCM operation at the minimum peak input voltage:

(38)

Calculate inductor value:

(39)

14.5 COFF Current Source

Choose capacitor C12=470pF.

Calculate resistor R16:

(40)

Calculate maximum on-time, minimum switching frequency and maximum switching period:

(41)

Calculate maximum and minimum duty cycles:

(42)

AN-2127 LM3448 A19 Edison Retrofit Evaluation Board SNOA559B–October 2011–Revised May 2013

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