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VSYS_MON of TPS659037

Michi Yama
Guru 10030 points
Other Parts Discussed in Thread: TPS659037

Hi,

I have questions regarding VSYS_MON comparator of TPS659037.

As you know, TPS659037 has 4 comparators (POR , VSYS_LO, VSYS_MON and VBUS_WKUP_UP) with power sequencer.According to my understanding,

VSYS_LO register and VSYS_MON register are following.

VSYS_LO(VSYS Low threshold) register is used for decision of transition from BACKUP state to OFF state, and request transtion (On request).

VSYS_MON(VSYS Monitoring) register is used for decision of transiton from OFF state to ACTIVE state, and requested transition(ON request)

1) Are my understanding right? Are both registers used for other reason?

2) According to  page 71 of SLIS165C data manual,  it is written in the below.

"After start-up, the VSYS_MON comparator is automatically disabled."

Is VYSYS_MON comparator valid absolutely when start-up? Is it guaranteed?

3) Regarding question (2), can customer confirm that VSYS_MON comparator is enabled?

4) Why is VSYS_MON disabled automatically after start-up?

Please advise me.

I appreciate your quick reply.

Best regards,

Michi   

  • 0
    TI__Genius 16410 points
    Hello Michi,

    VSYS_MON comparator is used for 2 functions: VSYS_HI and VSYS_MON.

    VSYS_HI is the level which gates power-on. If VCC_SENSE is below VSYS_HI, the PMIC will not turn on. VSYS_HI is programmed in to OTP, and sets the default value of the VSYS_MON register. VSYS_HI is only applicable while the PMIC is OFF. But this comparator is always active when the PMIC is OFF (it can't be disabled), so we can guarantee its function during start-up.

    VSYS_MON is used while the PMIC is ACTIVE. After power-up, the VSYS_MON comparator can be used to generate an interrupt if the VCC_SENSE level drops below VSYS_MON register value. This function is disabled by default, and must be enabled through the VSYS_MON register through I2C. You can also use this register to read out if it is enabled (bit 7).

    I think this may answer your questions. If you still have additional questions, please let me know.

    Regards,
    Karl
  • 0 in reply to Karl Wallinger
    Guru 10030 points
    Dear Karl-san,

    Thank you for your quick reply. It is very helpful for me.

    I would like to ask you about my question 4).
    4) Why is VSYS_MON disabled automatically after start-up?

    Please give me your answer of 4).

    Best regards,
    Michi
  • 0 in reply to Michi Yama
    TI__Genius 16410 points
    Michi,

    The functional reason it is disabled after start-up is because the VSYS_MON.ENABLE register bit is defaulted to 0 at start-up.

    If you are asking the intention of the designer, it may be to reduce quiescent current when that function is not needed. Or it could be that the user needs to configure the voltage before it is useful for the system, so it is disabled by default.

    Regards,
    Karl