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DLP-7970ABP output power

kazola
Guru 18425 points
Other Parts Discussed in Thread: DLP-7970ABP, TRF7970A, TMP103, RF430CL330H, DLP-RF430BP, MSP430F5529, MSP430FR5969

Hi,

thanks to @Eddie we have developed a quite good antenna for the DLP-7970ABP. VSWR is 1.5. We have about 7 cm range depending on the tag.

However, we were wondering if it is possible for the DLP-7970ABP to output more power than the 200mW I read.

Please let me know and have a nice day :)

  • 0
    TI__Mastermind 38620 points

    Hi Kazola,

    I hope you are doing well!  Glad to hear you have a good antenna now! 

    The TRF7970A only has 200mW output power when supplied with 5V.  The launchpad supplies 3.3V to the boosterpack, which puts the output power at 17dBm or ~50mW(see table 6-3 in datasheet).  If you can supply 5V to the boosterpack, this will increase your range to some extent. 

    The other option is to implement a power amplifier.  This is much more complex.  At some point, there may be a boosterpack that includes an amplifier, but this is likely not any time very soon.  I suggest trying the higher supply voltage first.

    Also, on another note, I remember you had done some work with the RF430CL330H using the NFC field to power the MSP430.  We recently put out a TI Design that implements this and also includes a TMP103 that we can use to create a battery-less temperature sensor.  Have a look at the link below in case you have not already seen this.  There is also a video at the bottom of that page which shows it in action. 

    http://www.ti.com/tool/tida-00217

  • 0 in reply to Eddie LaCost
    Guru 18425 points

    Hi Eddie,

    Regarding DLP-7970ABP

    as always, thanks for your time :) You answer is very useful, I will try your suggestion. I do not have any problem doing a video showing our quite long range with the new antenna for the DLP-7970ABP and the corresponding Smith Charts. Let me know if this could be useful for a wiki or similar!

    One question: for one project we should be able to read a phone placed downside the NFC reader's antenna. I mean, the display facing the NFC antenna. This is the other way around than traditionally but by now I cannot get any reading even with my new antenna, since being the phone's NFC antenna printed in the battery's back attenuates the signal too much. Any idea? :)

    Regarding DLP-RF430BP

    Yes, indeed I was able to use the DLP-RF430BP and a MSP430F5529 with no power! :) That was great. The following link contains my demostration video, let me know if it is useful to you.

    Standalone RF430CL330H video

    So, when I approach a phone to your new design, the MCU measures via I2C and stores the value thanks to FRAM, isn't it? And afterwards I can retrieve it? This is better than before, since we couldn't save the values until now :) Let me know if I have not understood the thing correctly.

    Have a nice day! :)

  • 0 in reply to Eddie LaCost
    TI__Mastermind 26420 points

    Eddie LaCost said:
    If you can supply 5V to the boosterpack, this will increase your range to some extent. 

    The TRF7970A can handle up to 5 V, but the MSP430 is not rated this high.  Please take caution on the launch pad as to not also power the MSP430 with 5V, since this will most likely damage the MSP430.

    Thanks,

    JD 

  • 0 in reply to kazola
    TI__Mastermind 38620 points

    Good point JD!  I am sure Kazola knows this and would use a seperate VCC for TRF vs. MSP430, but it is good you mention this to prevent someone else from making this mistake.

    Regarding DLP-7970ABP

    Sure, a video could be useful.  You can post it to the forum and I will make it sticky to help other members.

    You will not be able to communicate with the phone in this manner.  The phones battery acts as a shield, so no RF will penetrate through.  The phone would need to be specifically designed with the intention of reading tags from the front side.  I am not aware of any phone that is designed like this. 

    Regarding DLP-RF430BP

    The current implementation does not actually store the data in FRAM, but this definately could be implemented with the MSP430FR5969 used.  This feature would be more useful when there is a battery connected.  I think this would be a nice feature to add to the firmware for the future.   

    The field powered use case is typically for instaneous type measurements.  In these cases, we can store the data on the phone as it is read.