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CC1310 4x4 TX current consumption too high

will wang43
Expert 1205 points
Other Parts Discussed in Thread: CC1310

hi all

 I have a module using CC1310 4x4, and I found its RF TX current is very high: about 60mA. But its standby mode is about 1uA.

 Test condition is as below:

1.VDDS 3.3V, VDDR 1.95V

2. rfCarrierWave code, 14dB

3. SmartRF06 Evaluation board + my module.

4. All the jumpers on the baord is removed.

It is very strange, can somebody tell me why?

Thanks!

  • 0
    TI__Guru**** 317180 points
    The current consumption is dependent on the antenna. If you have an antenna that is far from 50 ohm the current consumption could be higher than stated in the datasheet (measured with 50 ohm load). As a test, terminate with 50 instead of the antenna and re check the power consumption.
  • 0 in reply to TER
    Expert 1555 points
    TER, this is quite worrying for wearables and similar scenarios because proximity (or distance) to the body can detune an antenna even if it is properly tuned well most of the time. (In my application the PCB is attached to an animal, but the issue is the same; it's hard to guarantee a good match in every transmit cycle).

    It is understood that if nearby tissue detunes the antenna, outgoing packets might not be received, but a 3x current consumption can lead to bad effects even after the antenna environment returns to normal. Two bad things that can happen is (1) fast discharge of a battery and (2) voltage drop that causes BOR or something similar due to internal resistance that's low enough for 20mA but not for 60mA.

    Is there a way to run the transmitter so that current is limited to something close to what's in the datasheet even if the antenna is not matched well?

    Thanks, Sivan
  • 0 in reply to sivan_toledo
    TI__Guru**** 317180 points
    This will always be a issue for small PCBs on sub 1 GHz frequencies. The antenna tuning is dependent on the ground plane and having the device close to the body will present a different ground compared to if the device is left on a table or similar.

    Either you have to tune the antenna for the most common use case and expect a degraded performance otherwise and/ or look into current monitoring (step down the output power at high current draw) or if possible adjust the antenna tuning dynamically with a varactor or similar.