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TPS65266: TPS65266 enable power sequencing

Peck
Prodigy 230 points
Part Number: TPS65266

Hi,

From the datasheet:

min/typ/max

VENXH EN1/2/3 high-level input voltage:-/1.2V/ 1.26V
VENXL EN1/2/3 low-level input voltage: 1.1V/ 1.15V/-

Question1 - Does this information means:

- If I want to enable: set 1.2V to 1.26V max?

- If I want to disable: 1.1V to 1.15V?

What should be the correct voltage level to enable and disable the IC?

Question2 -

I have a +5V input & 3 outputs (Vout1 = 1.0V@3A, Vout2 = 3.3V@2A, Vout3 = 1.5V@2A).

I need the following sequence: 5V input -> 3.3V -> 1.0V -> 1.5V output.

Can I do this:

1) set EN2 to open

2) output of Vout2 (3.3V) connect to EN1.

3) output of Vout1 (1.0V) connect to EN3. (can 1.0V voltage enable this buck3?)

4) output of Vout2 will be 1.5V (last)

Thank you

  • 0
    TI__Genius 9550 points

    Question1 - Does this information means:

    - If I want to enable: set 1.2V to 1.26V max?----->set the voltage no lower than 1.26v

    - If I want to disable: 1.1V to 1.15V?----------->set the voltage no higher than 1.1V

    What should be the correct voltage level to enable and disable the IC?

    Question2 -

    I have a +5V input & 3 outputs (Vout1 = 1.0V@3A, Vout2 = 3.3V@2A, Vout3 = 1.5V@2A).

    I need the following sequence: 5V input -> 3.3V -> 1.0V -> 1.5V output.

    Can I do this:---->the setting is wrong. please find my suggestion.

    1) set EN2 to open

    2) output of Vout2 (3.3V) connect to EN1.

    3) output of Vout1 (1.0V) connect to EN3. (can 1.0V voltage enable this buck3?)--------->can't enable the buck3

    4) output of Vout2 will be 1.5V (last)

    my suggestion:

    leave EN2 open, connect EN1 to C1, connect EN3 to C2;(C1 and C2 another terminal connect to GND)  the cpacitance C1<C2 (see datasheet figure 27)

    Jason Wang

  • 0 in reply to Jason Wang (BSR-MV)
    Prodigy 230 points
    In this case we are using capacitance to delay the power sequencing. There are 3 outputs, if one of the outputs is faulty I dont want the other outputs to continue (there is only 1 powergood).

    If I want to ensure 5V is up before 3.3V, 3.3V is up before 1.0V and 1.0V is up before 1.5V can my method be done?
    Anyway how to interpret (from the datasheet)?:

    min/typ/max

    VENXH EN1/2/3 high-level input voltage:-/1.2V/ 1.26V
    VENXL EN1/2/3 low-level input voltage: 1.1V/ 1.15V/-
  • 0 in reply to Peck
    TI__Genius 15135 points

    Hi,

    1. If want to one of the outputs is faulty, and don't want the other outputs to continue.

    ANS: we can use SS1 to control EN2, SS2 to control EN3, SS3 to control EN4.

    SSx signal will ramp up to 1.7V from 0V, when SSx>0.6V, this channel soft start is end and normal working; when SSx>1.26V, it will enable next channel.

    If this channel is faulty and shutdown, the SSx will be pull down to 0V, then it will disable next channel. But please be noted: the ENx internal pull-up current will affect the soft start time, the Tss calculation should plus ENx pull-up current.

    2. The VENXH and VENXL threshold have variaitions, it is different from parts to parts.

    When ENx voltage > the MAX VENXH=1.26V, we can ensure all mass production parts be enabled.

    When ENx voltage < Min VENXL=1.1V, we can ensure all mass production parts be disabled.