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TPS65070 enable pins connection

Evgeniy Emelyanov
Prodigy 20 points
Other Parts Discussed in Thread: TPS65070, TPS65073

TPS65070 datasheet claims on page 33 "Depending on the sequencing option, the signal at EN_DCDC1, EN_DCDC2 and EN_DCDC3 are ignored. For automatic internal sequencing, the enable signals which are not used should be connected to GND". What happens if I connect them to high level?

More specifically, I need to turn some DCDCs on and off while system operating, and I do not care of predefined automatic power up/down sequencing. I beleive if I connect pins EN_DCDC2 and EN_DCDC3 to GND it won't be possible to control the DCDCs after changing DCDC_SQ[0:2] to 101. Is there a way to resolve that issue?

I would not like to use TPS65073 because of its DCDCs current ratings.

  • 0
    TI__Genius 17240 points

    See my comments below

    Evgeniy Emelyanov said:

    TPS65070 datasheet claims on page 33 "Depending on the sequencing option, the signal at EN_DCDC1, EN_DCDC2 and EN_DCDC3 are ignored. For automatic internal sequencing, the enable signals which are not used should be connected to GND". What happens if I connect them to high level?

    [D.A.] If DCDC_SQ[2:0]= 101 and EN_DCDC1, EN_DCDC2, EN_DCDC3 are set to high, the corresponding converter starts up with soft start.

    More specifically, I need to turn some DCDCs on and off while system operating, and I do not care of predefined automatic power up/down sequencing. I beleive if I connect pins EN_DCDC2 and EN_DCDC3 to GND it won't be possible to control the DCDCs after changing DCDC_SQ[0:2] to 101. Is there a way to resolve that issue?

    [D.A.] In order to enable/disable the converters of the TPS65070 you will need to toggle the enable pins after writing DCDC_SQ[0:2] to 101 as you have said.

    You could use pull-up resistors on the enable pins to AVDD6 so that the TPS65070 will turn on all the converters, then use the microcontroller GPIOs to ground and disable the desired converter(s). 

    Keep in mind that DCDC_SQ[0:2] will have to be set each time the TPS65070 power is cycle or /PB_IN is held low for 15s.

     

     

  • 0 in reply to Daniel Acevedo
    Prodigy 20 points

    Thank you for your answer. Just for clarity, if I set EN_DCDC2=High and EN_DCDC3=Low than (with default settings in DCDC_SQ[0:2]) DCDC2 will turn on regardless of state DCDC3? Even if DCDC3 does not have its inductor and is not connected to source voltage?

    If that is correct I am going to use DCDC2 as primary power source, DCDC1 as secondary turnable source which is off at system start (to set non-default voltage before first turn on), and leave DCDC3 unconnected.

  • 0 in reply to Evgeniy Emelyanov
    TI__Genius 17240 points

    My earlier answer should be this (I corrected above): The sequencing option programmed needs to be DCDC_SQ[2:0]= 101 so when EN_DCDC1, EN_DCDC2, EN_DCDC3 are set to high, the corresponding converter starts up with soft start as