• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 65 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

TPS62140: continuous tracking

TPS62147: continuous tracking SS/TR 1-10V

Fredrich Lindberg
Prodigy 20 points
Part Number: TPS62147

Tool/software:

Hi
Im using TPS62147, Vin = 12V Vout <=> Variable tracking voltage on SS/TR pin (1-10V). 1:1 ratio.
e.a I want the Vout tracks the SS/TR voltage, with ratio 1:1.

Result: It's stuck @ Vout = 9.6V, when changing the SS/TR voltage 1-10V. (Nothing happens)

Is the schematic correct to do that?

I have tried other values of R18, no variable tracking as result.

What's wrong?

//Fredrich

  • 0
    TI__Genius 14121 points

    Hi Fredrish,

    Please make sure you made a right resistor divider for SS/TR.

    If the SS/TR pin voltage is above 0.7 V, the internal reference voltage is clamped to 0.7V and the device goes to normal regulation. This works for rising and falling tracking voltages with the same behavior.

    I attach app note for your reference:

    https://www.ti.com/lit/an/slva470a/slva470a.pdf?ts=1726629264533&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS62135

    Thanks,

    Colin

  • 0 in reply to Colin Chen
    Prodigy 20 points

    Hi Colin

    Thanks for the reply, you comment make sense.

    Please bring this note from me to the datasheet team:

    When you read the datasheet it say 9.4.6 "...A voltage supplied to SS/TR can be used to track a master voltage. The output voltage follows this voltage in both directions up and down in forced PWM mode..." nothing about what you did say "If the SS/TR pin voltage is above 0.7 V, the internal reference voltage is clamped to 0.7V and the device goes to normal regulation." if that was in the datasheet I would do it accordingly to that feature, and not need to ask the forum for an advice.

    Q: Are there any limit how low SS/TR pin could be and the regulation still works?

    //Fredrich

  • 0 in reply to Fredrich Lindberg
    TI__Genius 14121 points

    Hi Fredrich,

    Thanks a lot for your meaningful suggestion! I will transfer you message to datasheet tem.

    The regulation set by SS/TR works as longa as when 0V<SS/TR<0.7V. But i would like to remind you SS/TR=0V , there is a offset voltage 11mV on FB pin.  

    Anyway, I am very interested in your design.

    Could you give more information of this application and system block diagram to my email: colin-chen@ti.com

    Maybe I can give you more support if you need.

    Thanks,

    Colin