02100004 Rev 1
CCPF-3500-XX User Manual
Page 11 of 15
5.3 Using a CCPF with multiple PFNs or capacitors
In applications where the power supply has to charge 2 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. Also, a resistor must be in parallel with each diode
to help the power supply to “see” the cap voltage which 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.
