SNVS690I January 2011 – August 2021 LMZ14201H
PRODUCTION DATA
Operating frequency in DCM can be calculated as follows:
In CCM, current flows through the inductor through the entire switching cycle and never falls to zero during the OFF-time. The switching frequency remains relatively constant with load current and line voltage variations. The CCM operating frequency can be calculated using Equation 12 above.
The approximate formula for determining the DCM/CCM boundary is as follows:
The inductor internal to the module is 15 μH. This value was chosen as a good balance between low and high input voltage applications. The main parameter affected by the inductor is the amplitude of the inductor ripple current (I_{LR}). I_{LR} can be calculated with:
where
If the output current I_{O} is determined by assuming that I_{O} = I_{L}, the higher and lower peak of I_{LR} can be determined. Be aware that the lower peak of I_{LR} must be positive if CCM operation is required.