TPS55288EVM-045: Vout will be disable when change VOUT_FS Register(04h)

Hi Hardy,

Thanks for the post.

In the report, it wrote: Vout use res divider. What is the meaning? use external feedback?

In the external feedback mode, the Vref=1.2V.  The feedback ratio can't be changed. So I feel confused about your comments.

Hi Helen,

Thank you for your reply.

"Vout use res divider" is another circuit using for debug tool because the tool maximum input voltage is only 10V.

It is not for feedback, so you can see Vout is 3.53V when I setting Vout = 20V in GUI.

Also, the result is the same even if I don’t connect to this another res divider.

Best Regards,

Hardy

Hi Hardy,

Did you do the test based on the EVM board? or your own board?

What is the Vin, Vo/Io, and what is the experiment sequency?

Hi Helen,

I do the testing on EVM board and information as below.

Vin = 5V, Vout = 5V~20V, Rload = 460 ohm

1. Connect hardware and open GUI

2. Set Reg[04h] = 0x03 then enable output  //Vout = 5V 

3. Set Reg[00h] = 0xC0, Reg[01h] = 0x03  //Vout = 20V 

4. Set Reg[04h] = 0x00  //Vout 20V→5V

5. Set Reg[04h] = 0x03  //no output voltage

Best Regards,

Hardy

Hi Hardy,

I will double check the EVM board, please wait in patience.

Hardy,

I checked the EVM board, didn't found the issue. Please check the below Picture:

1. Vin=5V, Vo=5V

2. Vin=5V, Vo=20V

3. 20-->5V, the output is normal.

Could you please tell me how you change the Vout? Thanks!

Hi Helen,

I don't change Vout by Reg[00h] and Reg[01h] anymore when I finished the Step3. I only change Reg[04h] value.

3. Set Reg[00h] = 0xC0, Reg[01h] = 0x03  //Vout = 20V 

4. Set Reg[04h] = 0x00  //Vout 20V→5V

5. Set Reg[04h] = 0x03  //no output voltage

Best Regards,

Hardy

Hi Hardy,

Could you please show us the GUI page?

Hi Helen,

Update GUI information picture

3. Set Reg[00h] = 0xC0, Reg[01h] = 0x03  //Vout = 20V 

4. Set Reg[04h] = 0x00  //Vout 20V→5V

5. Set Reg[04h] = 0x03  //no output voltage

Best Regards,

Hardy