Hi Team,
my customer uses TPS552872-Q1 under these conditions:
Vout = 20V
Iout = 1.1A
Vin = 12V
Dither disabled
He is observing increased Vout Ripple in Auto PFM compared to FPWM Mode. The ripple is about 2x increased.
Do you have an explanation for this behavior?
Thanks and best regards,
Michael
Hi Michael,
This is the normal behavior.
With auto PFM mode, when Vout is higher than the target value, there will be no switching for all MOSFETs to reduce the power loss, so the efficiency is higher but the output voltage ripple is larger. It is recommended to choose FPWM to achieve lower voltage ripple, the switching frequency is constant at all loads.
Please see below for more detailed description.
BRs,
Bryce
Hi Michael,
At present we have thermal imagine of TPS55289 for reference with following conditions: Vin=12V, Vout=20V, Iout=2.25A, fsw=400kHz. With 1.1A load, the thermal performance will be better.
Regards,
Mulin
