first, sorry about my english.
Currently I'm working as project engineer developing an AC/DC power supply. The AC section is a resonant flyback and diode rectify to get 48VDC. With these 48 volts and 4 MAX17506 DC/DC buck controller, I obtain four 5VDC/3Amps outputs. Next picture is brief of my circuit.
As you can see, I rectify using a pairs of diode and clamping the voltage with two zeners, next a ten units of MLCC murata capacitors (2.2uF/100V X7R C1206) and single electrolytic cap (2200uF/63V). Following, four DC/DC buck converter using the MAX17506 IC. This it's working fine, but in several units the MLCC caps (caps before electrolytic) was literally blown to pieces. Things tested:
- Voltage capacitors are OK, 100 volts.
- No overcurrent and no overtemp.
- No shortcircuit.
- The polarity of electrolytic cap it's OK
The only clue about this mystery is what the electrolytic capacitor always be BEFORE MLCC caps, not after.