Datasheet

DocID14117 Rev 4 37/44
B5973D Application information
44
8.8 Synchronization example
See Section 5.3: Oscillator and synchronization on page 10 for details.
Figure 24. Synchronization example
8.9 Compensation network with MLCC at the output
MLCCs (multiple layer ceramic capacitor) with values in the range of 10 µF - 22 µF and
rated voltages in the range of 10 V - 25 V are available today at relatively low cost from
many manufacturers.
These capacitors have very low ESR values (a few m) and thus are occasionally used for
the output filter in order to reduce the voltage ripple and the overall size of the application.
However, a very low ESR value affects the compensation of the loop (see Section 7:
Closing the loop on page 17) and in order to keep the system stable, a more complicated
compensation network may be required. However, due to the architecture of the internal
error amplifier the bandwidth with this compensation is limited.
That is why output capacitors with a not negligible ESR are suggested. The selection of the
output capacitor have to guarantee that the zero introduced by this component is inside the
designed system bandwidth and close to the frequency of the double pole introduced by the
LC filter. A general rule for the selection of this compound for the system stability is provided
by:
Equation 41
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