The LM5168E is designed for buck
applications by operating in DEM mode, with light load PFM operation. Figure 8-1 shows the schematic for a 5V output buck regulator capable of delivering 300mA of
load current, using the LM5168E .
Note: In this data sheet, the effective value
of capacitance is defined as the actual
capacitance under D.C. bias and temperature, not
the rated or nameplate values. Use high-quality,
low ESR, ceramic capacitors with an X5R or better
dielectric throughout. All high value ceramic
capacitors have a large voltage coefficient in
addition to normal tolerances and temperature
effects. Under DC bias, the capacitance drops
considerably. Large case sizes and higher voltage
ratings are better in this regard. To help
mitigate these effects, multiple capacitors can be
used in parallel to bring the minimum
effective capacitance up to the required
value. This action can also ease the RMS current
requirements on a single capacitor. A careful
study of bias and temperature variation of any
capacitor bank must be made to make sure that the
minimum value of effective capacitance is
provided.