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BOOSTXL-CC1120-90: Current consumption of PA_EN & LNA_EN pins of CC1190 When driven from an MCU

Part Number: BOOSTXL-CC1120-90
Other Parts Discussed in Thread: CC1190, CC1120,

Tool/software:

Dear TI Team, 

I am using the CC1120 Transceiver in a project along with the CC1190 Power amplifier. My question here is that,  is it safe to drive the Power Amplifier Enable (PA_EN) and Low Noise Enable (LNA_EN) pins of the CC1190 directly from the MCU GPIO as we found that these GPIOs of our MCU stop working after some duration of operations. Please note that I'm driving the PA at maximum dBm. I couldn't find any information regarding the current consumption of these pins in the datasheet. All I could find regarding this is this graph, there it seems that the PAE current peeks to 350 mA(Not sure if this diagram is  referring to the PA_EN pin or the chip in whole when the PA is enabled). 

Would like your advise on the safest way to drive this pin i.e. PA_EN and LNA_EN 

  • Hi,

    Please can you clarify "drive the Power Amplifier Enable (PA_EN) and Low Noise Enable (LNA_EN) pins of the CC1190 directly from the MCU GPIO"? The CC1190 should be connected to the Sub-1 GHz RF pins (LNA_P, LNA_N, and TRX) of the CC1120, not any GPIO. Can you share your setup?

    The absolute maximum input RF level on any of the CC1190 RF pins (PA_IN, LNA_OUT, PA_OUT, and LNA_IN) is +10 dBm. Figure 6 is referring to the current consumption/PAE/Pout performance of the CC1190 device.

    Regards,

    Zack

  • Dear Zack,

    Sorry for the confusion,

    I was not talking about the LNA_P, LNA_N, and TRX pins, which in my design are connected between CC1120 & CC1190, as in the Reference design for CC1120-90 EVK. My doubt was regarding the LNA_EN (Pin7) & PA_EN (Pin8) of the CC1190, which are controlled from a MCU's GPIO if I have understood it correct.

    Regards, 

    Arun Raj

  • Hi Arun,

    Understood, thank you for clarifying.

    The LNA_EN and PA_EN control pins are intended to be driven directly from an MCU, but it is recommended to add 10 kOhm resistors to the lines (as in the reference design).

    The current peaks of 350 mA are the current consumption CC1190 device as a whole, not the current peak seen on the DIO pins.

    When you say "we found that these GPIOs of our MCU stop working after some duration of operations", is that with the BOOSTXL-CC1120-90 hardware or a custom design? Please can you give more specifics of the issue you are seeing?

    Regards,

    Zack

  • FYI we're always driving these enable pins directly from micro GPIOs, with about 10 - 15mA drive capability (or any standard CMOS output), but we have 100K pull-downs on these pins. Should not make any difference though. Since you mention your problem occurs after "some time" it seems like there might be something on the micro side that's causing your strife ... hope this helps.