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AWR2243: schematic questions about MMWCAS-RF-EVM

Shine
Genius 13655 points
Part Number: AWR2243
Other Parts Discussed in Thread: MMWCAS-RF-EVM,

Hello Champs,

Customer has some schematic questions about MMWCAS-RF-EVM.
https://www.ti.com/tool/MMWCAS-RF-EVM

1. In PROC054E_System_Power.SchDoc，what are the function of R189 and R191 100ohm resistors? Can they be removed?

2. In PROC054E_System_Power.SchDoc, PMIC1 is used for power supply, in theory, it only needs to use PGOOD on PMIC1 as reset signal. However, the PMIC1 PGOOD is "AND" to PMIC2 PGOOD to generate the SYSTEM_PGOOD as a reset signal.  Is there some special considerations? Can he only use the PMIC1 PGOOD? 

3. In PROC054E_AWR_1_AWR_4_LP87524P.SchDoc，PMIC_NRST is connected with both pullup and pulldown resistors. But according to the BOM, the pulldown resistor is not on the board. What is the function of the R58 pulldown resistor? Can it be removed? The same question for PMIC_BUCK_EN pin. 

4. In PROC054E_AWR_1_AWR_4_LC_Filtering.SchDoc，PMIC1_AWR_1_1V0 is divided into two parts by L4 and L5，AWR_1_1V0_RE1_FILR and AWR_1_1V0_RE2_FILR， and then provide the power supply for AWR1_2243 G5,J5,H5 and A2,B2,C2,D2. Why is it divided into two parts?

5. In PROC054E_AWR_Pull_Resistors.SchDoc, AWR2243 SPI_MOSI is connected to GND via R183, but in the AWR2243 datasheet, the SPI_MOSI is pullup in default. Which resistor should be connected to the pin, pullup or pulldown resistors?



Thanks.
Rgds
Shine

  • +1
    TI__Genius 13805 points

    Hi,

              Please find my response below:

    1. These resistors can be used for debug purpose to scope the NRST to AWR device.

    2. This is done to ensure that none of the devices RESET is released till the power supply is established across board(across PMICs/to AWR devices).

    3. The pull down is not populated and also in the design checklist the pull up and cap to GND is recommended.

    4. As the name of the nets suggest these are the RF supply ball pads. RF1 and RF2 are Analog and RF supply nets and are separately filtered to ensure no cross noise coupling happens.

    5. I think you are referring to two different things. The DS talks about status of PULL structures associated with the IO after device POWER UP. Where as the Board schematic is talking about the external recommended interface. This signal is also going to the HOST.

    Regards