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R.Gantner
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Ultra Low Power ADC

The DA14580 has a ultra low power ADC with 5µA @ 100 ksamples/s.
Is there any application note to use this adc @ 100 ksamples with low power ?
If I use timer 0 or timer 2 to trigger a conversion then I can not use the Deep Sleep Mode.
In the "normal" Sleep Mode the Power consumption is much higher.

JE_Dialog
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Hello , the only  example for

Hello , the only  example for ADC we have is in our peripherals apps note , UM-B-005. section 5.4.7

There is a an example in the SDK for this (batt_test inside DA14580_examples.c ) but its not using a timer to trigger that. Let me have a quick check to see if we have anything else coming.

Best regards,

JE_Dialog

R.Gantner
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To trigger the ADC with the

To trigger the ADC with the timer0-interrupt is not a problem but I can not use the timer 0 in extended-sleep-mode.
In the normal sleep mode the current consumption is about 500 uA and then the ADC ultra-low-current feature is useless ?!
Perhaps an other possibility could be to output the 32.768 KHz to a pin and then connect this pin to another pin and use the wake-up-timer to trigger the ADC - the only problem is that it looks like there is no possibility to output the 32.768 kHz.

JE_Dialog
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Hello, my apologies for delay

Hello, my apologies for delay in answering you : the system should have triggered an email to me when you posted, but i missed that. Let me raise your question with the team and i will work on seeing if we can find a solution to this.

BR JE_Dialog.

R.Gantner
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Hello,

Hello,
any update on this ?
Is there a way to trigger the adc with the 32.768 kHz Oscillator that the average power consumption is below 100 uA ?

RvA
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Hello,

Hello,
The minimum AD conversion time when you want to use the deep sleep mode is determined by the connection interval. The Bluetooth SIG defines a minimum connection interval of 7.5ms. So the DA14580 can go to deep sleep mode and wake-up again to do an AD conversion at this interval. This translates to 133 samples/s.

For 100ksamples/s the device needs to be in active mode. Power consumption can be reduced by switching the ARM core to idle mode in between samples, where the ARM current consumption would drop from ~600uA to ~333uA. Still on average you would be in the 400uA - 500uA supply current range (excluding any additional current required for processing the AD data and the radio). This is far away from the 100uA you requested.

A solution we can think of could be to use an external uC and ADC and use the DA14580 for handling the BLE protocol and RF. You can use the deep sleep mode mode of the DA14580 then and use the power saving mechanism of the external uC to reduce power.

Best regards, RvA (Dialog)

R.Gantner
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Hello

Hello
Thank's a lot for the detailed answer.
So it looks like the 5 uA @ 100 ksamples/s in the data sheet is more a theoretical value.
I don't need the 100 ksamples/s, I am satisfied with 32768 samples/s.
Instead to use a external uP, I will connect an external low power 32.768 kHz Oscillator to a Port an use the wake-up to trigger the DA14580 internal ADC.

RvA
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Hello,

Hello,
The 5uA typical supply current at 100 ksample/s in the data sheet is for the ADC only. So that excludes the ARM being active and the RF.

In case you would use an external oscillator to wake-up the DA14580 at 32kHz intervals (every 31us) you would have 488 clock cycles (16MHz / 32kHz) to do an AD conversion, process/send the data from the ADC and go to sleep mode.

For obtaining an average current 100uA you need to be active for ~ max. 81 clocks and in extended sleep mode for ~ 407 clocks. So all processing should be done in roughly 81 clock cycles.

Best regards, RvA (dialog)

R.Gantner
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Hello,

Hello,
In the DA14580 datasheet table 6 the typical startup time (deep-sleep to software start) is 1 ms.
It looks like the 1 ms startup time is also needed from the Extended Sleep Mode.
Is there a way to do a faster startup from GPIO change to software start ?
With the RC16M it should be possible to do it in some µs.

JE_Dialog
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Hello R Gartner,

Hello R Gartner, unfortunately there is a weakup handler that introduces this 1mS delay between interrupt and start, even thouggh RC16 is active.

BR JE_Dialog