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CC1200: Current consumption in sniff mode according to number of preamble

Aratrika Kundu
Prodigy 200 points
Part Number: CC1200


Hi,

I am configuring sniff mode in my application since i need to reduce my current consumption. I followed the excel sheet provided in this link (http://www.ti.com/lit/zip/swra428).

From this i understood that, major part of current consumption depends on the no. of preamble bytes . so on my receiver side i have configured the number of preambles as 30 since it consumes least current. although my transmitter is configured for 8bytes. When i measured the current on my RF board, i am observing that the current is ~8.2mA in all cases, irrespective of the preamble size configured on the RX size and i measured the current when there is no RF transaction. So my understanding is that, when the receiver is not receiving anything, the current consumption should be  ~1.8mA when configured for 30 bytes preamble.

can you help me understand the scenario?

PQT Termination
Bit rate: 19200kbps, Osc Freq:40MHz
No of preamble Expected Current consumption Actual Current consumption
8 8.260 mA 8.260 mA
24 2.306 mA 8.260 mA
30 1.814 mA 8.260 mA

  • 0
    TI__Guru**** 317180 points

    The details are covered in the app note (https://www.ti.com/lit/pdf/swra428) but based on the question some basics has to be highlighted:

    The basic principle can be covered based on the following figure: 

    The main idea: The RX current consumption in average will be lower if the interval between each time the device starts RX could be longer. At the same time we want to ensure that we are able to detect a packet if on the air. To do that the preamble (on the TX side) has to be slightly longer than the interval the receiver side goes up in RX.  

    Preamble is only used on the TX side. When in RX the number of preamble is not used for anything. On the RX side the timing is set by the WOR events. Please use the sniff mode tab in SmartRF Studio to visualize and calculate the required parameters.