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AMIC110: Power-up sequencing

Hideaki Matsumoto
Genius 9765 points

Part Number: AMIC110

Hi,

The customer has some questions regarding Figure 6-6. Power-Supply Sequencing With RTC Feature Disabled in the AMIC110 Datasheet.

 

1) Could you share any document which describes each timing [ms] or [us] ?

        I think there is no timing spec, need to keep only ramping order and follow the note A to G, right ?

 

2) When they don't use 3.3V,

     Can VDD_MPU, VDD_CORE, VDDS_RTC, CAP_VDD_RTC, VDDS_DDR and All other 1.8V Supplies be ramped at the same time ?

 

Regards,
Hideaki

  • 0
    TI__Guru**** 393215 points

    Hi,

    Hideaki Matsumoto said:
    I think there is no timing spec, need to keep only ramping order and follow the note A to G, right?

    Correct.

    Hideaki Matsumoto said:
    When they don't use 3.3V, can VDD_MPU, VDD_CORE, VDDS_RTC, CAP_VDD_RTC, VDDS_DDR and all other 1.8V Supplies be ramped at the same time?

    No, VDD_MPU, VDD_CORE and CAP_VDD_RTC must still be ramped-up AFTER the 1.8V supplies.

  • 0 in reply to Biser Gatchev-XID
    TI__Genius 9765 points

    Hi Biser,

     

    Thanks for your reply. According to the Figure 6-6 and its notes,

     

    D. If the system uses mDDR or DDR2 memory devices, VDDS_DDR can be ramped simultaneously with the other 1.8-V I/O power supplies

     

    Figure 6-6 shows All other 1.8-V Supplies and VDDS_RTC are ramped at the same time.

     

    E. VDDS_RTC should be ramped at the same time or before CAP_VDD_RTC

     

    Figure 6-6 shows CAP_VDD_RTC, VDD_CORE and VDD_MPU are ramped at the same time.

     

     

    From these descriptions, I thought that VDD_MPU, VDD_CORE, VDDS_RTC, CAP_VDD_RTC, VDDS_DDR and all other 1.8V Supplies can be ramped at the same time.

     

    What do you think about this my consideration ?

     

    Thanks and regards,

    Hideaki

     

  • 0 in reply to Hideaki Matsumoto
    TI__Guru 64015 points

    Note “E” associated with Figure 6-6 only describes a relationship between VDDS_RTC and CAP_VDD_RTC.

     

    The relationship of VDD_CORE and VDD_MPU supplies with respect all other supplies is completely different. The VDD_CORE and VDD_MPU supplies should be the last to ramp and should not begin to ramp until all other supplies are valid.

     

    It is possible to use the same power source for VDD_CORE, VDD_MPU, and CAP_VDD_RTC. However, you must consider all power supply sequencing requirements when you do this. The CAP_VDD_RTC supply must follow the same power sequencing requirement as VDD_CORE and VDD_MPU once you connect CAP_VDD_RTC to the same source as VDD_CORE and VDD_MPU. Therefore, you cannot use the relationship described in note “E” to define a relationship for VDD_CORE and VDD_MPU supplies with respect to other supplies.

     

    Regards,

    Paul