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TPS5402 COMP pin

Prodigy 140 points

Replies: 6

Views: 991

Hi,

I am designing a buck converter based on TPS5402 chip. By reading the datasheet I don't understand the criteria to choose Rc and Cc values.

It says " Error amplifier output and input to the PWM comparator. Connect frequency compensation components to COMP 6 this pin"

Can someone help me with this issue? 

Thank you.

  • They don't really cover that at all in the datasheet do they? The TPS5402 is just current mode control. Are you an experienced dc/dc converter designer? If so you can just design the compensation as you normally would. If not I can possibly help you with it. Let me know your input and output voltage and current requirements. Have you already chosen Cout and Lout?

    Best  Regards,

    John Tucker

    BSR-MV DC/DC Applications

     

    “Working on an automotive power design? Read the E2E technical article Meet European Commission ADAS requirements with TI DC/DC for device recommendations and other helpful resources.”

     

  • In reply to JohnTucker:

    I have no experience designing dc/dc converter. This is my first design. I dont want you to spend much time with this, so as long as you can provide me a guide to understand this problem it will be fine.

    My requeriments are input voltage between 5-24v and fixed output voltage around 4-5v (I am not sure if it can work with 5v input voltage and 5v output voltage) . Output current around 1A its fine.

    Basically what I'm designing is the power stage of a battery powered device which should work with either a solar cell or wide voltage DC conection (5-24v)

    Thank you.
  • In reply to Mario Avila:

    I would probably use this document to calculate compensation:
    http://www.ti.com/lit/ds/symlink/tps54040.pdf
    Start on page 33. Make sure to use the parameters from TPS5402, gmps = 9 A/V, gmea = 92E-6 and vref = 0.8 V.
    Let me know if you have problems.

    Best  Regards,

    John Tucker

    BSR-MV DC/DC Applications

     

    “Working on an automotive power design? Read the E2E technical article Meet European Commission ADAS requirements with TI DC/DC for device recommendations and other helpful resources.”

     

  • In reply to JohnTucker:

    Thank you so much! This application note was really helpful.

    I have a last question. Those equations are related with Vout. What happen if Vout is not fixed?
  • In reply to Mario Avila:

    That's one of the disadvantages of current mode control. The loop response will change with Vout. If your Vout does not change much you can design a circuit that is stable over the range of output voltages. If you need a wide range of adjust ability, you may be better off with voltage mode control.

    Best  Regards,

    John Tucker

    BSR-MV DC/DC Applications

     

    “Working on an automotive power design? Read the E2E technical article Meet European Commission ADAS requirements with TI DC/DC for device recommendations and other helpful resources.”

     

  • In reply to JohnTucker:

    Thank you again! Very helpful.

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