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CC1121: About LDO for power supplying to CC1121.

Kazuya Nakai59
Guru 20100 points
Part Number: CC1121
Other Parts Discussed in Thread: TLV700, LP5907, TPS782, LP5900, TPS62740

 Hello guys,

 One of my customers is going to use CC1121 for their next products.

 Also they are considering using one of following LDOs for CC1121.

TLV700　SOT-23-THIN

https://www.ti.com/product/TLV700

 

LP5907   SOT-23-THIN

https://www.ti.com/lit/ds/symlink/lp5907.pdf

 

TPS782　SOT-23-THIN

https://www.ti.com/product/TPS782

 

LP5900　WSON

https://www.ti.com/product/LP5900

 

 Could you please tell me the LDO if any of these LDOs are not suitable for CC1121 power supply?

 

 Your reply would be much appreciated.

 

 Best regards,

 Kazuya.

 

  • 0
    TI__Guru**** 317180 points

    Which input voltage and output voltage for the LDO do you target? 

    Have you a buck/ boost converter (TPS62740 family) to save current? 

  • 0 in reply to TER
    Guru 20100 points

     Hello TER,

     Thank you for your reply.

     LDO input voltage is 2.5V (min) and output voltage is 2.2V.

     They want to use LDO as the power supply of CC1121 for lower cost, and high PSRR, low noise.

     Also they think that all of these LDOs can supply the current which CC1121 needs.

     Could you please tell me if you have any concern to use these LDOs for CC1121?

     Thank you again and best regards,

     Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Guru**** 317180 points

    The CC1121 has internal LDOs with good PSRR, do they need a LDO?

  • 0 in reply to TER
    Guru 20100 points

     Hello TER,

     Thank you for your reply.

     I have CC1121 datasheet, version SWRS111F.

    https://www.ti.com/lit/ds/symlink/cc1121.pdf.

     Could you tell me where I can see a description for the LDO in the datasheet?

     Is it "2.0–3.6 V VDD to internal digital regulator" in setion 3.2 Pin Configuration on page 6?

     Thank you again and best regards,

     Kazuya. 

     

  • 0 in reply to Kazuya Nakai59
    TI__Guru**** 317180 points

    The spec of the internal LDOs is not covered in the datasheet but I have fairly good overview of the PSRR of the internal LDOs since I designed some of them.

    Could you share the spec for the full power system? 

    CC1121 is designed be connected to a power source without having to include a LDO with high PSRR. If you are unsure of the performance you can buy some CC112x modules and test if the performance is degraded by your power system or not.  

  • 0 in reply to TER
    Guru 20100 points

     Hello TER,

     Thank you very much for your reply.

     I understood CC1121 has high PSRR LDO internally.

     I will get the full power system and share with you on new thread.

     Thank you again and best regards,

     Kazuya.