Using Curr Meas pin on SmartRF06 to measure current consumption

PATRICK OHARA

Hello,

I'm using the SmartRF06 with a CC2650EM. I'd like to measure the high frequency current consumption of the BTLE module. I have my MDO3014 connected to the Curr Meas pin and the ground connected to the pin next to it (labelled GND). The output of the scope is shown below. I expect to see the current increase as the BTLE module advertises for connection. If this signal is here, it's buried in the low frequency noise. Is there anything special that I need to do to use the current measurement connector on the SmartRF06. The documentation indicates that this is the output of a Op-Amp with gain. So, I should be able to connect it directly to my scope. Any suggestions would be appreciated.

Thanks,

Patrick

over 9 years ago

0 YiKai Chen over 9 years ago

Guru 735685 points

Try to refer to application note "Measuring Bluetooth ® Smart Power Consumption" for CC26XX.

0 PATRICK OHARA over 9 years ago in reply to YiKai Chen

Genius 3205 points

Thank you for your comment. I read with interest the application note that you referenced. Unfortunately I don't have the Agilent power analyzer that is described in the app note. I do have a very nice Tek MDO3014. I'd like to use this scope to make the measurements described in the app note. Of course, I could simply measure the voltage drop across a 10 ohm resistor in series with the "VDD to EM". But I want to use the amplified differential amplifier on the SmartRF06. The output of the amplifier is very noisy - as shown in the previous post. Could you connect an oscilloscope to the SmartRF06 and post a screen shot of what "Curr Meas" signal should look like during advertising?

0 Igor Sherer over 9 years ago in reply to PATRICK OHARA

Guru 31280 points

Hi Patrick,

I have measured the amplified voltage and got a pretty nice picture.

Image 1 is my setup, image 2 is what I captured with my oscope.

Could you make a photo of your smartRF06 board, specifically the are marked in Image 3 (preferably with a high resolution).

There might be no op-amp assembled.

Image 1 - Setup

Image 2 - Oscilloscope snapshot

Image 3 - OpAmp area

0 PATRICK OHARA over 9 years ago in reply to Igor Sherer

Genius 3205 points

Well.... That explains a few things. When I first hooked up my scope I thought, "it doesn't look like it's attached to anything." That's because it's not. The amplifier is not installed. I should have checked this earlier. Thanks, Igor for your thoughtful response and effort. I guess I'll breadboard my own differential amplifier across a shunt resistor. With all the other stuff on this Dev board, I'm a little surprised TI didn't install these components.

0 Igor Sherer over 9 years ago in reply to PATRICK OHARA

Guru 31280 points

Hi,

I have two different revisions of smartRF06EB, and guess what, on rev 1.2.2 the op-amp isn't installed, while on rev 1.2 it does.
That's why I asked you to take a snapshot.

0 YiKai Chen over 9 years ago in reply to Igor Sherer

Guru 735685 points

I had seen similar on my SmartRF06 and I ask my distributor for replacement. You can try to contact TI www.ti.com/.../gencontent.tsp for replacement.

0 Igor Sherer over 9 years ago in reply to YiKai Chen

Guru 31280 points

I wonder what might be the reason for not placing op-amp components on the last revision of the board.

0 YiKai Chen over 9 years ago in reply to Igor Sherer

Guru 735685 points

I am curious on this too.

0 TER over 9 years ago in reply to YiKai Chen

TI__Guru**** 317180 points

Sorry about slightly late reply to this.

The opamp for current measurement was removed from the latest version of the SmartRF06 since the design didn't work good enough.
- The way the opamp is powered the power consumption of the opamp will be a part of the measured power
- The dynamics was not large and linear enough to measure power profiles
- It was not fast enough to measure power profiles.

0 YiKai Chen over 9 years ago in reply to TER

Guru 735685 points

It's good to know this. Thanks.

0 PATRICK OHARA over 9 years ago in reply to TER

Genius 3205 points

TER

Thanks for the clarification. You may want to change your documentation to reflect the current HW. This will save others from time spent on unneeded troubleshooting of hardware that doesn't exist.

Igor provided a nice oscillograph using older HW. Although there may be issues with accuracy, the visualization is helpful.

Patrick

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Using Curr Meas pin on SmartRF06 to measure current consumption