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AWR1243: Questions regarding MCU_CLKOUT/ PMIC_CLKOUT and current consumption

Faiz Ahmed
Intellectual 460 points
Part Number: AWR1243

Hello,

I had couple of questions regarding the clock signals and also the current consumption of the chip:

1)  What is the purpose of the MCU_CLKOUT? If the MCU has its own oscillator, wouldn't the commands be synchronized through SPI clock and the data though LVDS clock?

2)  How does the PMIC_CLK work? From my understanding, it's used to synchronize the switching of the PMIC with the chip. Is that correct?

3) How are the current values determined in Table 5-3? Are those  the maximum current that can be drawn from the supply? VIN_13RF1 and VIN_13RF2 is listed as 2000mA but we didn't see anything close to that from our test. Is there a way to determine the maximum drawn current based on our settings?

Thank you,

Faiz

  • 0
    TI__Mastermind 37500 points
    Hello
    The MCU clock output is a 40-50Mhz signal aligned to the Slicer output. It is not required.
    Depending on the Pin Mux, it may not be used.

    The PMIC Clock is a divided clock, that can be used for a PMIC clock. However the PMIC clock needs to be present before the PMIC starts, or have an I2C command sequence to switch to the external clock. The means to modify the PMIC clock is to move the CLK, 2xCLK spurs out of the radar Rx signal of interest. In the default software, this function is not enabled.

    These are user specific. you could modify the EVM to measure each RF1, RF2 with a series resistance, it should be VERY LOW, or with a small wire loop with a clip on current probe. Other than the Max current listed , we have to measure specific cases with a modified EVM.

    Regards,
    Joe Quintal
  • 0 in reply to Radio-Joe
    TI__Guru 58035 points
    Hello Faiz,
    To add to what Joe mentioned , you are right that just for the SPI communication and LVDS data capture you don't need to synchronize the MCU clockout. In the single chip use case this is more of an option to reduce having a separate clock for the MCU, but its not mandatory to use.

    With regards to the current numbers in table 5-3, these are the peak currents during the transmission , in the worst case scenario and can be used for power budgeting on the PCB. But typical scenarios may have lower currents. You can get some idea about expected current in your scenario by using the power estimation spread sheet ( www.ti.com/.../swrm018).

    Regards,
    Vivek