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IWR1843: 1V and 1.3V modes

Guy Shemesh
Prodigy 245 points
Part Number: IWR1843

Hello,

On a custom board that we're making we're using the IWR1843 with LP87524J (direct 1V output with external LC filters).

1. I'd like to know, in the DS there is a mention of 1V LDO bypass mode which means as I understand that the internal LDOs of the IWR1843 on the pins VIN_13RF1 / VIN_13RF2 are disabled. 

As I understand these internal LDOs receive 1.3V and supply internally 1V. First off all, is this correct? please confirm. 

2. Second question, what needs to be done on the hardware side in order to use the LDO bypass mode and supply 1V directly to VIN_13RF1 / VIN_13RF2 ?

So far, I didn't see any special pin / other setting that needs to be done to use that mode other than just supplying the 1V on VIN_13RF1 / VIN_13RF2.

3. Third question please. I see in section 5.6 power consumption summary, note (1), that in case of using 3 transmitters simultaneously 1V should be connected to the VOUT_PA directly. 

Please recommend, should I just put decaps on VOUT_PA as on the EVM, or should I also connect it directly to my 1V supply. 

Thank you

Guy

  • 0
    TI__Mastermind 25835 points

    Hello Guy,

        1) Yes, your assumption is correct.

        2)  If you use the LP87524J PMIC then 1.3V volt rail needs LDO bypass option. You could feed 1V from the LP87524J PMIC and you need to issue LDO bypass API command from mmWave SDK link layer.

    Documentation for this you could refer to SDK.  You should refer to mmwavelink doxygen (mmwave_sdk_<ver>\packages\ti\control\mmwavelink\do

    cs\doxygen\html\index.html) on the usage of this API and call this API from their application before calling MMWave_open().

    You could refer below excerpt from the mmWave link layer documentation. 

    3) Yes, you need to connect VOUT_PA to 1V supply along with the Decaps connected on Vout_PA. (This is recommended only in 1V mode).

    Thanks and regards,

    CHETHAN KUMAR Y.B.

  • 0 in reply to CHETHAN KUMAR Y.B.
    Prodigy 245 points

    Dear Chethan,

    Thank you very much, all clear now

    Guy