Dear TI Team:
Please help to check UCC2897A schematic, Input is DC 160V, output 12V/25A and 24V/12.5A, 300W.
Hi Eric,
Page 1 and Page 2 of the schematic are almost identical except that Page 2 has a zener diode on the VIN pin.
The 51k resistor presents a high impedance to VIN and the UCC2897A may not be able to start up and operate due to this.
Usually there is a bias winding on the transformer and this provides power to the VDD input.
Can you confirm that this is a real design and that the component values are accurate ?
I notice also that the LINEOV and the LINEUV have the same DC value.
Therefore I recommend that the Excel calculator should be used to calculate the correct component values for all of the circuit components.
This would be a good check on the component values.
Regards
John
