I want to modify the ADP1046A-100_EVALZ to get the 24Vin, 5Vo/6A.
I change the R10 of main board from 10ohm to 20ohm, and R5/R7/R10 of Daughter card from 11Kohm to 4Kohm, and R1 of Daughter card FROM 27Kohm to 12Kohm.
And below is some questions.
1. The Vin in GUI monitor just around 10V in the no load.
2. The Vin slow increase based on the load increase, but only up to 21V(It should be 24V).
Could you please advise the root cause?
Sorry for the late response. I have not received the notice for your question.
since the turn ratio of the main transformer is 2:1. when the Vin is 48V, the voltage plateau of the secondary side sw node is 24V, so the R1 in the daughter card should be 23k to get a voltage of 1V to ACSNS pin. when you modify the Vin to 48V, the voltage plateau of the secondary side sw node is 12V, so the R1 in the daughter card should be 11k to get a voltage of 1V to ACSNS pin.
however, since the switching node is noisy. there are huge ringings especially at heavy load. if you add an RC filter to filter the ringing, the Vin sense accuracy will be much better. please refer to the circuit below.