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MMWCAS-RF-EVM: PMIC control signals

Antonio Puglielli
Expert 1025 points
Part Number: MMWCAS-RF-EVM

Hello,

In the MMWCAS-RF-EVM schematic, the control signals for the PMIC (e.g. I2C, EN, NRST, etc) are pulled up to the "PMIC1_3V3" rail. That rail is generated by a 1ohm/1.96kohm divider from the 5V supply, which makes it seem that it is actually a 5V rail. Is that correct? Is it expected that the pullups go to 5V? What are the requirements on the driver of those signals?

Thanks,
Antonio

  • 0
    TI__Mastermind 18470 points

    Hi Antonio, 

    The VANA pin determines the LP87524P digital input max voltage. With VANA set to 5.0V, this sets the max to 5.0V. See the LP87524P datasheet, table 6.3, recommended operating conditions table: http://www.ti.com/lit/ds/symlink/lp87524p-q1.pdf#page=5

    However, the intention was for R34 and R59 to be populated with 1.0kohm resistors resulting in a ~3.3 high pull voltage being generated from the 5.0V system rail so that any interfacing MCU host logic would see maximum 3.3V on those pins. I'll note this.

    Thank you,

    -Randy