The
Secret Of TPS51225
It is usually said that after the standby
chip has the main power supply and linearity is turned on, it will usually
output the reference and linearity,
but I don't pay much attention to it during
maintenance.
This standby chip TPS51225 is a bit special.
First of all, I looked at the pin names.
There was no abnormality. I took it for granted that if there is a main power
supply, there will be a linear output..
Looking at the pin definitions again, EN1
controls PWM1 and EN2 controls PWM2. There seems to be nothing special.
Looking at the control relationship again, we found the problem. When EN1 and EN2 of TPS51225B are low, VREG5 is turned off. Only VREG3 is turned on.
When EN1 and EN2 of TPS51225C are low, VREG5 and VREG3 are all turned on.
Finally, looking at the timing diagram, it
shows that this TPS51225B needs to get EN1 before it can turn on VREG5.
The TPS51225 and TPS51225C will output two
linear lines after getting the main power supply VIN.
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