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CC1101: The schematic diagram review

Zhang Liang
Genius 3360 points
Part Number: CC1101

Hi,

Please kindly review the schematic diagram that the CC1101 has no TX and RX signal,  

The waveform of the power supply during transmission is normal, with a floating range of<30mV. Ripple<20mV, thanks.

  • 0
    TI__Expert 4220 points

    Hi Zhang,

    The most critical error I found is that DCOUPL should not be connected to VDD.

    The only connection to this pin should be the 100nF decoupling capacitor. Image below from reference design.

    I also noticed that the decoupling capacitors for AVDD are different than the reference design. In the reference design it uses 220pF and 20nF capacitors depending on the pin, while in your design, it seems that 100 nF capacitors were used for all of the AVDD pins.

    Finally, the DGUARD pin should only have a 220pF capacitor.

    Image below from reference design.

    You can find the CC1101EM reference design for 433 MHz here: www.ti.com/.../swrr046

  • 0 in reply to Diego P
    Genius 3360 points

    Hi,

    This is the pilot production and the fault rate is 27%(8/30) , we have no idea if we don't change the PIN5 design and is there any other improve for this design, thanks?

  • 0 in reply to Zhang Liang
    TI__Expert 4220 points

    Hi Zhang,
    PIN5 (DCOUPL) needs to be disconnected from 3.3 V in the design. This pin is used only to connect the decoupling capacitor for the internal 1.6 - 2.0 V digital power supply. In your current design you are shorting 3.3 V to the internal power supply.

    You are also exceeding the maximum voltage allowed on the DCOUPL pin.


    Images above from the datasheet: https://www.ti.com/lit/ds/symlink/cc1101.pdf

  • 0 in reply to Diego P
    Genius 3360 points

    Hi,

    Because we have pilot production the error design about 100boards, so please advise if we can do something on the current boards, thanks.

  • 0 in reply to Zhang Liang
    TI__Expert 4220 points

    Hi,

    For testing, you may be able to cut the trace the connects DCOUPL to 3.3 V and just keep DCOUPL connected to the decoupling capacitor. If you can do this will depend on the board layout.