02100005 Rev 1
CCPF-500 CCPF-750 User Manual
Page 13 of 17
5.3
Using a CCPF with multiple PFNs or capacitors
In applications where the power supply has to charge two or more separate capacitors,
which are discharged at different times, diodes must be used in series with the output to
prevent one cap from discharge into the other. In addition, a resistor must be in parallel
with each diode to help the power supply to “see” the cap voltage that is now blocked by
the diodes. Failure to add the parallel resistors will result in over charging the cap as the
power supply does not see the real voltage on the caps.
The diodes must have voltage rated at least 300V higher than the max voltage and 2 times
the current.
The resistor values are calculated as follows:
R (in Ohm) >= 100 * Vout.
P (in Watts) >= V^2 /R.
