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TPS54821: Some question about overvoltage

Part Number: TPS54821
Other Parts Discussed in Thread: AFE7921,

Tool/software:

Hi,

    We used TPS54821 to power up  AFE7921,but when I reset our AFE7921,the Voltage will drops.The AFE7921 power up must be follow Power-on sequence,the datasheet suggest powergood to control next step power enable.

We found that when I reset AFE7921,the second step power will drops,and the first step powergood is falling

see below

And I also found that the first step power was rise when I reset our load so that trig the Output Overvoltage Protection,our load AFE7921 when runs,the voltage is 0.9V and  current is 4A

see below

 ..

We are try to modify the different Switching Frequency,we try 300kHz,500kHz,1000kHz,1500kHz,but it can not solve this problem.

And we also try to modify different frequency compensation,but it also can not solve this problem.

And we also try to add Electrolytic capacitors to output to increase ESR,but it also can not solve this problem.

And we also try to add resistance to GND in output ,but it also can not solve this problem.