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TPS65218D0: clarification on data sheet for AC_DET connection and also Queiscent current

ajayt
Genius 9555 points
Part Number: TPS65218D0
Other Parts Discussed in Thread: AM4376,
  1. We are using a TPS65218D0 to power a AM4376 CPU
  1. In the TPS manual there is a mention that the AC_DET has to go to IN_BIAS(which is around 5V) if not used
  1.                                                                i.      But for Bootup is says AC_DET must be Grounded

 

 

Please clarify.

We also will have no power button – the power up will be done by connecting a cable to a connector  which will then power  some DCDC converter and then IN_BIAS and all other inputs of the PMIC.

 

 

  1. Do you have a reference on the power consumption of the PIMC from the Coin Cell – we are trying to estimate the life of a Coin cell battery in our system or if 2 batteries are needed or a charging circuit + rechargeable battery

 

  1. RTC_KALDO_EN Pin. Section 6.4.3.5 Internal RTC LDO of technical reference says "If your application uses the RTC functionality and requires RTC-only mode, the internal LDO is required to enable proper wakeup signaling from the RTC domain.

The proper wakeup signaling requires the following connections:

  • RTC_KALDO_ENn is grounded
  • CAP_VDD_RTC is connected to 1uF decoupling capacitor to ground
  • RTC_PWRONRSTn is connected to 1.8V RTC power on reset
  • PMIC_POWER_EN is connected to power input of PMIC
  • RTC_WAKEUP (EXT_WAKEUP0) is connected to a wakeup source"

 

Our design and the General Purpose reference designs have RTC_KALDO_ENn pulled to VDDS_RTC.

Please comment – which one is the right connections

 

  • 0
    TI__Genius 12735 points

    Hello,

    The expert for this device is out office today and is expected back in office tomorrow, 08/25. Please expect a response from him tomorrow.

    Best regards, 

    Layne J

  • 0
    TI__Mastermind 30310 points

    If there is no push-button in the system, the AC_DET pin on the TPS65218D0 must be connected to GND.

    This means the PMIC will try to turn on any time VIN_BIAS > VUVLO.

    The TPS65218D0 + AM437x system was designed to operate off of a non-rechargeable coin cell battery for >1 yr while keeping the RTC domain alive. This allows the product to sit on a shelf for up to 1yr before shipping to the end customer, which is a relatively standard requirement. Combined, the TPS65218D0 + AM4376 RTC domain will consume approximately 10uW in the RTC-only mode when only DCDC5/6 are enabled, powered from the coin cell.

    For the remainder of your question, I will need to re-assign to the AM437x Sitara processor team to let you know the correct termination of RTC_KALDO_ENn pin.

  • 0
    TI__Guru 63145 points

    If you connect RTC_KALDO_ENn to VDDS_RTC, the internal LDO which sources the RTC core power domain will be disabled. This means the RTC core power must be provided by an external source.

    How are you suppling power the CAP_VDD_RTC pin (RTC core power domain) when the internal LDO is disabled?

    Regards,
    Paul