Hello, i’m using MPQ4323 to supply GSM mode, by means of a P-mos swithed by uC output. My modem is SIM7060, with 400 uF on Vbat rail. I have 24V input with 4,2 Vootput, 2,2 Mhz 4,7uH inductor. The issue is that after switching, the DC/DC switch off the output, probably for OCP. How can i fix it? there is another PN that fits better this applciation? changing component dimensiong?BR
Hello John,
It would be better to diagnose the waveforms what happens before and after the MPQ4323 shuts off.
Also, do you have a schematic to provide here? Let me know when you can.
hello Krishan, thanks for reply. in annex the Vmain on C90 near the SIM7600. the peak current measured is 3,8A, and after 200 us the OCP shutoff the output. could be better to use MPQ4324 or 4334? any other pin to pin compatible? i wanna be sure also if i increase total Cout amount that still works.
X2
this plot show the voltage behaviour on capacitor C90, shows after 200 us the output shut down. the scenario is when a power MOSFET is powered on, so to connect Vmain to the GSM module. the connection is beetween two different board, by means of a ribbon flat cable.
OCP is very likely the culprit here as the MPQ4323 can only handle up to 3A.
Is the 3.8A peak to be expected in the system behavior? It looks like the current here is clamped and could go higher. I see nothing wrong with the schematic you provided so perhaps a converter with a higher current threshold like the MPQ4334 would be warranted if you would like to test this out. It would certainly yield you a better efficiency.
These two ICs have the same package and pinout, so you should be able to drop these in place of the MPQ4323.
Best,
Krishan
is che current that you could have with quick mosfet swithing, on 450 uF cap.
are availble PN that manage better current pulse?
Perhaps so, a higher current rating will usually help with this, but double check this info in the MPQ4334 datasheet. Is this something you would consider testing in practice?
yes, i could abruptly switch the power mosfet supplying theg modem to test it