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RN2483 deep sleep current consumption

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microhubbe
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2016/02/16 02:13:18 (permalink)
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RN2483 deep sleep current consumption

As I get no response from Microchip at all - perhaps out there in the user community I get some more valuable information...

We don't manage to get the deep sleep current in regions below 10µA. The datasheet claims this current to be typ. at 1.8µA.

We only have the serial lines TxD and RxD and the Reset-Pin connected to our controller. Even if we cut these lines during sleep, there is no change in the current consumotion (-> no significant leakage current).

The idle current is approx. 2.8mA (correct typical value stated in the datasheet).


History:

At first we only had modules with firmware 0.9.5. and the sleep current was about 65µA.

So we thougth an improvement could be setting all GPIOs etc. of the RN2483 to outputs to avoid any floating input bahaviour (although we did this test already with external voltage levels - with no improvement).

But first problem was that the command "sys set pinmode <pinname> <pinFunc>" did not exist in firmware 0.9.5. (as correct stated in the datasheet...)

But how to upgrade to firmware 1.0.0.

As there is no info on the Microchip website on how to perform an upgrade we finally found this valuable posts:

(thanks James C)

Here the desperate customer can download a JAVA application, the firmware and an instruction on how to update the module.

After gaining this knowledge we also found the hex-file with the firmware 1.0.0. on the Microchip server but not the important JAVA application and not any further information - so I wonder why they advertise with the "bootloader" but keep it as their secret.

Anyway we managed to update the RN2483 to firmware 1.0.0 and got an immediate improvement of the sleep current by 30µA so that the consumption dropped to 35µA.
But also with the new available command (sys set pinmode...) there is no further improvement possible.
The 35µA are still far away from 2µA.

To avoid any misunderstanding:
Our circuit consumes 10µA idle without the RN2483.
But as soon as it is added to the circuit (=soldered on the PCB) the current rises to 45µA (of course after the RN2483 module was put to sleep - at power up you first get the idle current of 2.8mA).
So the netto current consumption of the RN2483 is 35µA. And once more: we only have 3 lines connected (Reset, TxD, RxD) and of course the supply lines, decoupled with ceramic resistors and the antenna pin.
There is no significant change when we disconnect the Reset TxD RxD lines during sleep. No change when we program all unused Pins of the RN2843 to outputs with the command "sys set pinmode...".
Supply voltage is 3,3VDC.

We have an active ticket for the Microchip support but we didn't get any feedback up to now and I doubt we will...

Has anybody made the same experience or any hint / information on how to achieve the lowest possible deep sleep current with this module?

Thanks in advance!
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    Bluedelta
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    Re: RN2483 deep sleep current consumption 2016/02/16 13:09:33 (permalink)
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    microhubbe
    We don't manage to get the deep sleep current in regions below 10µA. The datasheet claims this current to be typ. at 1.8µA.



    This is the LoRa module, right? Page 7 of the datasheet seems to specify deep sleep current of .0099mA, which is in fact 9.9uA.
     
    Can you probe current going directly to the module when its on the board? (Put in a prototyping jumper, etc.)
     
    Make sure the presence of the module isn't causing other elements on the board to 'become upset', heh.
     
    Finally, trying I/O pins to input with weak pull-ups may help.
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    microhubbe
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    Re: RN2483 deep sleep current consumption 2016/02/16 13:21:29 (permalink)
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    Thanks for you reply Bluedelta!
     
    I just got an answer from the microchip support - and they said that it is unfortunately a known problem. There does also exist a new errata sheet, where this topic is stated - I just got the link sent by Microchip.
    A current below 40µA is obviously awsome and unbeatable as it might be as high as 140µA.
    There is also a new firmware 1.0.1 but even with this firmware the problem is not solved.
    They hope to fix it in future releases but can't promise anything right now.
     
    Anyway this is a very sincere answer and I am really greatful for that. Sorry Microchip for my unpatience!
    So I am searching for another similar product right now - but of course I will switch back to Microchip when they got the prolem fixed.
     
    Thanks all for the assistance!
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    Bluedelta
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    Re: RN2483 deep sleep current consumption 2016/02/16 13:33:25 (permalink)
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    microhubbe
    Thanks all for the assistance!


    Oh, sure. You know, as it has turned out to be a bug, there is always the technical possibility of using an external 'supervisor' to simply disconnect the module when out of use.
     
    May or may not raise your BOM a bit, but a useful note if you don't find another module you like. Microchip has a good bit of micropower analog and cheap supervisory controllers.
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    microhubbe
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    Re: RN2483 deep sleep current consumption 2016/02/16 13:56:17 (permalink)
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    Thank you Bluedelta!
     
    Well, indeed this was our first attempt.
    We used the MIC94091 (from Microchip - former a Micrel product) - but we were afraid of the overal startup time.
    We are using this module in keyfob transmitters (only the radio commands) where fast reaction is very important. The spread spectrum technics of this module slow down the reaction and thats why we wanted to speed it up wherever possible but using the long range - with the spread spectrum.
    So we preferred the sleep state, as RAM keeps saved and transmission might be initiated at once as soon as the module is waked up (any key is pressed).
    There are several LoRa-Products on the market right now and we will discover, if some have reasonable "radio commands" and current saving technicss
     
    Thanks anyway!
     
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