• State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 62 subscribers
  • Views 350 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TPS3896: TPS389X Understanding working principle

Mehmet Eyup Arslan
Intellectual 745 points
Part Number: TPS3896


Hi,

I have a system that has 2 power inputs that I am working on, one of these inputs can be 1 continuously, the other second power input can be 1 in a maximum of 10 seconds.

What I want to do is;
If the 2nd power input does not go high within 8-10 seconds, reset the regulator controlling the 1st power input.
Can I watch the system by waiting for 8-10 seconds, with any device of TPS389X.

This is my first time working on this, can you help? If I couldn't explain the issue, please ask, I'll try to help you in more detail.

Best regards,

Mehmet

  • 0
    TI__Intellectual 1210 points

    Hi Mehmet,

    Just so I can make sure I am understanding your system correctly, you have 2 power rails. One of these power rails is active continuously, the other comes up after a delay period (8-10s).

    1. Do you want to monitor only the one (second, delayed period) power rail?

    2. And then the output of this monitoring should be used to control the first power rail?

    Jake

  • 0 in reply to Jake F
    Intellectual 745 points

    Hi Jake,

    1) My 1st power rail will always be 1 (high).
    2) My 2nd power rail can be 1 (high) in 8-10 seconds.

    Yes, I think you got it right. If my 2nd power rail does not become 1(high) in 8-10 seconds, I want to reset my 1st power rail.

    Best regards,

    Mehmet

  • 0 in reply to Mehmet Eyup Arslan
    TI__Intellectual 1210 points

    Hi Mehmet,

    A supervisor, such as the TPS3896 can be used to monitor the 2nd voltage rail and the RESET output of this supervisor can be used to control the EN of the first rail. One thing however is that this device won't necessarily wait for the 8-10 second delay. It will be constantly monitoring the rail and if it is ever outside of a defined operating range, the RESET will be toggled.

    Jake

  • 0 in reply to Jake F
    Intellectual 745 points

    Hi Jake,

    I understand in general, there is one point I would like to clarify. Isn't it enough to put the required capacity for 8-10s delay on the CT pin?

    for exp: If I put a value like 2.2uF on the Ct pin, can't I get about 9s delay according to the formula in the datasheet?

    (datasheet 8.3.4 Output Delay Time Pin (CT) )

    I would like to reiterate my purpose.


    - We set our delay time to 9 seconds. For example, my 2nd rail became 1(high) in 6 seconds. Will it still reset our 1st rail? (9 seconds is not over yet.) This is the most important issue.

    Thanks,

    Mehmet

  • 0 in reply to Mehmet Eyup Arslan
    TI__Intellectual 1210 points

    Hi Mehmet,

    Yes, the delay time can be set to about 9s based on the equation in the datasheet. 

    To answer your question, when the 2nd rail becomes 1 (high) in 6 seconds, then there will be a period of 9 seconds, and then the SENSE_OUT output will be asserted. This is the function of the delay, figure 3 in the datasheet explains the relationship of the SENSE to SENSE_OUT with the delay included.

    Jake