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TPS65910: TPS65910 RTC

usercnh75516
Prodigy 180 points
Part Number: TPS65910

hi, dear

      In my design, the PMIC RTC is used for a back-up RTC , when the AC/BATTERY is not present. we use a super-capacitor (3.3V 200mF) to supply the RTC power, series a 10 ohm resistor for current limit.

refer to the datasheet, when AC/BATTERY is not present, VBACKUP is the only power supply. as shown in the datasheet, the power consumption is 6-9uA. 

according to the condition, would you please help to calculate how much time will the RTC of PMIC be maintained?

thanks

  • 0
    TI__Genius 17380 points
    Hello,

    Looking at the datasheet, it looks like VRTC will continue to operate until VBACKUP < VBNPR (Figure 5-3) which has a max value of 2.2 V. If discharging a capacitor with a max 9 uA from 3.3 V to 2.2 V, and delta V = I*t/C, then I calculate a worst case time of 6.8 hours.