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TPS65140EVM-031: Vo3 output issue.

Nicky Lim
Genius 3195 points
Part Number: TPS65140EVM-031

Hello, 

Under TPS65140EVM-031 testing and make output voltage as below.

VIN : 5V

VOUT1 : 10V 

VOUT2 : -6V 

VOUT3 : 21V

To make a wished output voltage, modified FB resistors as below.

It works properly without LCD connection, at first. But after connecting LCD, Vo3 output voltage up to 25.3V.

After that, V03 output voltage is always 25.3V even not connecting LCD.

To make Vo3 = 21V,  is there any other setting needed?

And why Vo3 output is raised to 25.3V?

Please let me get your answer ASAP.

Regards,

Nicky

  • 0
    Genius 3195 points
    Hello,

    Is there any updates?
    Please let me get your answer ASAP.

    Thanks & Best Regards,
    Nicky
  • 0 in reply to Nicky Lim
    TI__Expert 8010 points

    Helly Nicky,

    Did you check VO1 ? From the value (R3) you have chosen, the voltage is supposed to be 12 V.

    If you want VO1 to be 10 V, R3 should be 56 kOhm.

    In the current configuration you will not be able to achieve 21 V on VO3. I have following suggestions for you:

    • If VO1 = 12 V --> remove second charge pump stage (remove C7, leave pins C2+/- floating)
    • If VO2 = 10 V --> exchange R3 to be 56 kOhm

    Please let me know which configuration is required.

    Thank you.

    Best Regards.

    Ilona

  • 0 in reply to Ilona
    Genius 3195 points
    Hi Ilona,

    I have question about your comment as below.
    Does it mean that I cannot achieve 21V on Vo3 anyway?
    or If I choose one of your suggestions, I can achieve 21V on Vo3?


    In the current configuration you will not be able to achieve 21 V on VO3. I have following suggestions for you:

    If VO1 = 12 V --> remove second charge pump stage (remove C7, leave pins C2+/- floating)
    If VO2 = 10 V --> exchange R3 to be 56 kOhm

    Regards,
    Nicky
  • 0 in reply to Nicky Lim
    TI__Expert 8010 points
    Hello Nicky,

    What I meant was that in the current configuration you will not be able to achieve 21 V. Only if you choose one of the suggestions.

    Best Regards.
    Ilona