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TM4C129ENCPDT: RTC hardware Design

Nishitha Chandrasekar
Intellectual 700 points

Part Number: TM4C129ENCPDT

Hi Sir

 I am working in TM4C129ENCPDT controller. I am new in this filed. I have a doubt in RTC hardware connection. For RTC implementation in my custom board. I have two doubts

1. Whether 32.768Khz crystal is required? if it is required tell me why it is required.please explain me

2. For Vbat connection i have referred system guidelines. They have mentioned RC filter with 3V battery whether Vdd (3.3v) is required ??? if required means guide why it is required .

  • 0
    TI__Guru**** 191886 points

    Nishitha Chandrasekar said:
    1. Whether 32.768Khz crystal is required? if it is required tell me why it is required.please explain me

    The RTC is used to keep the wall time. You can use a 32.769Khz crystal or an 32.768kHz oscillator. If you use the 32.768kHz oscillator then you just connect to the XOSC0 input and leave the XOSC1 open. Please refer to the datasheet for details. Below are excerpt from the datasheet.

    Nishitha Chandrasekar said:
    2. For Vbat connection i have referred system guidelines. They have mentioned RC filter with 3V battery whether Vdd (3.3v) is required ??? if required means guide why it is required

     You can connect the VDD to the Vbat pin if you do not have an external battery in which case there is no need of the RC filter. The recommended RC filter is meant to ensure the maximum Vbat battery supply voltage ramp time is met which is 0.7V/us as shown in the datasheet.