Tool/software:
Hi Sir,
we are now designing the turns ratio of the Voltage regulator for TPS23731, and we need 10v output, is our turns ratio correct? also , what is the role of R16?
we hope you can help check if there anything other that need to be modifyied in this schematic, thanks for your help and lrean from you.
Hi Tommy,
R16 is mainly for current limiting for charging the PSR cap C40 during startup. R16 also increases damping factor against noise during steady state.
For your 10V output:
1. You need to make R18 connected: PSRS is only open if your 2nd side is sync FET, otherwise please tie PSRS to RTN.
2. According to the turns ratio SEC : AUX = 9 : 8, VCC voltage will be closed to ~10V / 9 * 8 = 8.9V. But considering there are some forward drop by diodes, the VCC could be less than 8.5V UVLO. It is recommended to use 0.67 < SEC : AUX < 1.
3. You can calculate the regulation resistance by FB = 1.75V and Vreg = 10V / Nsec * Naux
For other parts review, please go with the attached check list first and let me know if you have any specific questions:
0435.PoE PD Schematic Checklist.xlsx
Best regards,
Diang
