Welcome Guest,Register Now
Log In

ANT Forum

Welcome guest, please Login or Register

   

power consumption

Rank

Total Posts: 11

Joined 2011-06-28

PM

Hello,

What i'm looking for is to calculate the average current
for AT3 module when using ADC with one of its analogue ports.

So, does the average current of the electrical specification
of AT3 considers the operation of the ADC or they are just
for the wireless part. Also it seems to me that it is not specified
which mode is used (Asynch or Synch).

Thanks in advance      
Avatar
RankRankRankRank

Total Posts: 745

Joined 2012-09-14

PM

If you are using the AT3 in SensRcore mode which allows for standalone ADC transmission then the average consumption drops as neither synchronous or asynchronous communication is used. If you wish to use the AT3 with an external microcontroller and the ADC simultaneously then you can use a formula closer to:
IMsg_Tx_BitSync + IBase + (ISample * Sample_Rate) for synchronous communication or
(IMsg_Ack_57600 * Message_Rate) + IBase + (ISample * Sample_Rate) for asynchronous communication.

You can find example calculations of average current consumption for the AT3 module on page 12 of the "ANT AT3 Transceiver Module Datasheet" document found here.

Cheers      
Rank

Total Posts: 11

Joined 2011-06-28

PM

Thanks a lot,

i read the datasheet and i found for the current base in active mode is 2.6uA for AT3, but when i read the file about power consumption states "Power States" i found the current in active mode for AT3 with external clock is 2.5 mA, same thing for AP2. So does these values have different meanings?

Thanks in advance      
Avatar
RankRankRankRank

Total Posts: 745

Joined 2012-09-14

PM

Hi,

The active state current in the power states app note is representative of an instantaneous moment of high activity, such as if a message is being processed and transmitted on the serial line or if a channel is in searching mode. The base current is representative of the radio with zero activity occurring.

Cheers      
Rank

Total Posts: 11

Joined 2011-06-28

PM

Hello,

Actually the current consumption are not so clear to me. first of all, in the power state documents, are these values change if we are using RX or TX especially in the case of TX if we use different transmission power like 0dBm or else. other thing,it is mentioned in the nRF24LO1 datasheet that the current is around 13.3mA at 0dBm for TX only which is also mentioned as average current in AT3 datasheet. which is something different from the 3mA that is mentioned in the power states file.

on other hand, I used AT3 as a TX only with message rate of 4Hz and ANT+ key using also the ADC with sampling rate of 4Hz, the LED was turned on to check the transmission. I checked the current consumption using the oscilloscope and I've got something I didn't expect. in spite of getting a spike for each transmission, I've got two noticeable small spikes followed by a peak which I assume that it represents the transmission. on other hand, if I zoomed into the spikes I found several small spikes covering the whole curve.

So I would like to know how actually is the device working and how the constructions are applied to the module so me I can understand the meaning of these spikes, because I want to calculate the current theoretically and compare it with a practical measurements especially there is only atable of the electrical calculation that is mentioned in the AT3 file and no deep explanation about that or about power graph or current consumption signal.

I attached two files:
first image Print_00: is a window before and after a TX
image2: print_004: is a zooming into one of the spikes, where the small spikes can be observed

Thanks a lot, and sorry for the long question      
Avatar
RankRankRankRank

Total Posts: 745

Joined 2012-09-14

PM

Hi,

The number provided in the app note is based on the approximate average current consumption of a module performing TX/RX because ANT is a duty cycle based protocol. The 13 mA number provided in the datasheet is representative of the peak current for Tx only, not the average current consumption over a whole period of ANT activity.

Although your files did not attach properly, I will state now that the internal operation of the ANT protocol is proprietary and cannot be disclosed. If you wish to determine your average current consumption under specific use cases you may use the calculations mentioned in the respective datasheet or use the power estimator found here.

Cheers      
Rank

Total Posts: 11

Joined 2011-06-28

PM

Hello,

I'll try to attach the pictures again
the name are the same as explained in
the previous message. [file name=Print_0_4.pdf size=21634]http://www.thisisant.com/images/fbfiles/files/Print_0_4.pdf[/file]