I have a question about ADP2118.I'm useing ADP2118 in the following condiiton; Vin-5V, Vout-3.3V(Duty: about 0.7).But how should I caluculate Minimum vallue of INDUCTOR?I can't find any caluculating fomula on the datasheet.
I also consder ADP2164, but I can't find the infromatoin on minimum value of Inductor.Please tell me if the calucuating fomula is the same as ADP2118.
The datasheet just say something like that;The ADP2118 uses slope compensation in the current loop to prevent subharmonic oscillations when the duty cycle is larger than 50%. The internal slope compensation limits the minimum inductor value.
the min inductor value for the ADP2118 is around 1.5uH. It is not described in the datasheet because different inductors (even if specified at 1.5uH) may have lower inductance at full load.
The best way to determin the min inductance for the internally compensated parts is to actually use the design tools and select from list of available inductor values. That list not only considers the min and max inductor values but also considers the inductance value of the part under the operating conditions.
ADP21xx Buck Regulator Design Tool
supports: ADP2105, ADP2106, ADP2107, ADP2108, ADP2109, ADP2118, ADP2119, ADP2120, ADP2138, ADP2139, ADP2164