Hi Team,
The new design of a motherboard scheme, in which the power part uses the circuit of TPS65251 which has been verified before, but when the board comes back, TPS65251 has no output, the old and new schematic diagram is as follows:
The major failures of the new version are as follows:
The three outputs are 6.9V -0.5V 0.25V, respectively, and the first 6.9V has output only when the fuse is connected. After disconnecting the fuse, all three measurements are 0V.
V3V pin output is 0.25V, V7V pin output is 0.5V, ROSC is about 100mV aperiodic signal
All three EN feet are low (0.2V) and forced up to 3.3V will not work properly.
Modifying the capacitance value of SS1/2/3 has no effect on the results
Replacing the chip has no effect
With the old version test, the old version output and pin status are normal. I don't know where the problem is.
Best Regards,
James