Current mode Full Bridge with series capacitor in the bridge.

[cupoftea]

Hi,
Page 19 of the LTC3723-1 datasheet shows a 300W Current mode Full Bridge SMPS with a 4u7 series capacitor.
Can we agree that this capacitor doesnt need to be there?

LTC3723-1 datasheet

https://www.analog.com/media/en/technical-documentation/data-sheets/372312f.pdf

 

[Easy peasy]

Interesting that there is 5.1 ohms across it - this is a classic " trying to fix a cock-up" of layout in the one they built. They could not get it working properly with no cap ( as it should be capable of ) so they added a cap - but also the 5.1 ohm R to stop the cap charging too far one way due to the peak current mode control based on the source resistor for the bottom fets - this is a good sign to steer clear of this chip, unless you are a layout expert and have plenty of time to try and fix the chip deficiencies ....

--- Updated Nov 20, 2022 ---

Also - it is extremely unlikely that the ckt shown on p19 will work satisfactorily at light loads

--- Updated Nov 20, 2022 ---

actually the single ended take off the Tx for the pri side aux supply could have a lot to do with assymetry and the need for the cap and resistor ... see L3 on the ckt diagram.