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TPS6521905: Push button functionality with standby and switch supplies.

Terry Gould
Prodigy 55 points
Part Number: TPS6521905
Other Parts Discussed in Thread: TPS7A20, TPS65219

Tool/software:

We are using a AC to DC PSU with a 5V standby supply and higher current switched supply. The PSU has a power good signal for the switched supply.

We were hoping to use the push button functionality of the TPS6521905 to enable the switched supply of our AC/DC PSU.

Would it be possible to supply one of the LDOs from the 5V standby supply and the other 3 bucks and 3 LDOs from the switched supply. When the push button is pressed the LDO turns on to enable the switched supply, when the power good signal is activated then the other supplies turn on. 

Is this something that could be achieved with minimal external components?

I appreciate this may not be the clearest so I will upload a block diagram later.  

  • 0
    TI__Mastermind 19716 points

    Hi,

    Thanks for reaching out. The PMIC can be configured to have one LDO enabled by default and the remaining rails OFF. The challenge is that the remining rails would need to be turned-ON by I2C because the PMIC standby state can only be used to disable rails (using the STBY pin).

    I would recommend using an external LDO for the "standby supply" and the TPS65219 PMIC for the remaining rails (PMIC can be enabled with the power-good signal from the PSU). This PMIC comes in a very small 4x4mm package so even when combined with an external LDO, it still provides a competitive low cost/small BOM solution. How much current/voltage do you need on the LDO? We can help to recommend a small LDO (i.e. TPS7A20). 

    Thanks,

    Brenda