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NFC-DATALOGGER-EVM: "VCC_I2C" in NFC-DATALOGGER-EVM's schematic

weiji jiang
Expert 2040 points
Part Number: NFC-DATALOGGER-EVM
Other Parts Discussed in Thread: RF430CL331H, RF430CL330H, TMP112, OPT3001, HDC1000

Hi TI Folks,

  Good day to you.

  When I read the schematic of NFC-DATALOGGER-EVM, then confuse on the VCC_I2C:

  1. Where does “VCC_I2C” come from? What is the voltage level range to support the EVM operate normally?
  2. What is its power source? Is it from P2.6 of U1 (MPN MSP430FR5969IRGZ)

I also confuse on the supply voltage range on RF430CL330H and RF430CL331H:

1. The VCC supply spec in datasheets of RF430CL330H and RF430CL331H indicated as below, please teach me the difference in details:

    1.  3.0 ~ 3.6V: During program execution no RF field present
    2.  2.0 ~3.6V:  During program execution with RF field present

Best regards

Jiang WeiJi

  • 0
    Expert 2040 points
    Hi TI Folks,
    Good day to you.

    Addition one more question on NFC-DATALOGGER-EVM:
    What is different between “VCC” and “VCC_I2C” voltage level? Are there any issues to interface Master/Slave I2C devices in different voltage levels?

    best regards
    Jiang WeiJi
  • 0 in reply to weiji jiang
    TI__Mastermind 31600 points
    Hi WeiJi,

    Thank you for choosing TI products for your design. Let me review the layout, and I will get back to you soon.

    Aaron
  • 0 in reply to Aaron Heng
    TI__Mastermind 31600 points
    Hi WeiJi,

    I reviewed the layout and schematic. The only difference between VCC and VCC_I2C: VCC is connected to a 3V coin cell battery to power the MSP430 and RF430 NFC Transponder, and VCC_I2C is when two coils of the NFC phone and antenna on the EVM come together, the RF430 harvest the energy, and eventually powered the rest of the devices such as TMP112, HDC1000, OPT3001. The voltage level should be around 3.3V.

    Regarding to your power supply question about the RF field is present or not, you might want to post on RF430 forum so that RF430 team will give you the exact answer. Basically, it is related to the present of the antenna. We rectify the RF signal on the antenna, powered by harvested energy from NFC field, and use it to power our circuit.

    Hope this helps. Please let me know if you have further question.

    Aaron