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TPS65261-1: About the timing of EN1 and EN2 of Automatic Power Sequencing

Kaji@PAN
Mastermind 7145 points
Part Number: TPS65261-1

Hello,

I would like to ask you about the timing of EN1 and EN2 of Automatic Power Sequencing.
In the data sheet Figure 29, first of all, EN1 and EN2 are "H".
Is it necessary to set EN1 and EN2 to "H" before VIN starts up?

I am considering the configuration shown in the figure below.
I will adjust the timing when EN becomes 'H' by the resistance for setting EN after starting VIN.
Can Automatic Power Sequencing work this way?

The data sheet does not describe when the MODE, EN1 and EN2 settings are finalized in the Automatic Power Sequencing settings.
So it would be helpful if you could show me this information.

Best regards,

  • 0
    TI__Prodigy 560 points

    Hi Kaji,

    Our expert is checking this, If there is a result, I will reply in time

  • 0
    TI__Genius 15135 points

    Hi, Kaji 

    MODE, EN1 and EN2 can follow Vin timing. 

    But the EN3 signal must be late than MODE, EN1 and EN2. 

    So you should parallel a capacitor(0.1uF) with R4 to delay EN3 signal. 

  • 0 in reply to Zhao Ma
    Mastermind 7145 points

    thank you for your reply.
    I have additional questions.

    1.Is the order of rising MODE, EN1 and EN2 fixed?
      Is it necessary to start MODE after turning on EN1 and EN2 as shown in Fig. 29?
      Or should I turn on EN1 and EN2 after launching MODE?
      In my circuit, the voltage is divided by a resistor from VIN and the voltage is applied to EN, so there is a possibility that MODE will start up first.

    2. Does the threshold value for "H" and "L" of MODE, EN1 and EN2 match with 1.2Vtyp?

    3. How long does EN3 need to be turned on after MODE, EN1 and EN2 are confirmed?
      Is there a limit to the minimum time it takes to turn it on?

    Best regards,

  • +1 in reply to Kaji@PAN
    TI__Genius 15135 points

    Hi, Kaji 

    Q1: It is not necessary to follow the sequence in Figure29, it is just an example. 

    There is no sequence requirement for MODE, EN1 and EN2. The only requirement is that before EN3 is turned on, MODE, EN1 and EN2 must be ready. 

    Q2: Yes. 

    Q3: I would say 500uS is good enough.