Current Consumption RTC & RTC + 64 kB RAM Retention

[Mr_BLE]

Hello,

 

I have 2 questions:

1. Could you tell me the current consumption of a nRF52832  running RTC with external 32 kHz crystal and no RAM retention? Is it 1.9 µA?

2. Could you tell me the current consumption of the device, if everything is off except 64 k RAM retention and RTC running with external 32 KHz crystal? Can I easily calculate 1.9 µA + 0.7 µA?

 

Thank you!

Regards

Andre

[Stian Røed Hafskjold]

Hello,

• System ON base current: 1.2 µA
• RAM retention per 4 kB block: 30nA (64k RAM = 0.48 µA)
• RTC running: 0.1 µA
• LFXO running: 0.25 µA

Then you can just add the numbers:

1. SysON + RTC + LFXO = 1.2 + 0.1 + 0.25 = 1.55 uA
2. SysON + RTC + LFXO + 64k RAM = 1.2 + 0.1 + 0.25 + 0.48 = 2 µA

[Mr_BLE]

Hi Stian,

thanks for your efforts. But this is confusing: I found in the datasheet V1.4 of the nRF52832 different values. Additionally there are different values on the first page of the datasheet compared to the values in the middle of the sheet.

To 1.: The datasheet sais on page 77: ION_RAMOFF_RTC System ON, No RAM retention, Wake on RTC 1.9 μA. Why is this different to your value? Do I also have to add LFXO with 0.25 µA -> 1.9 + 0.25 = 2.15 µA?

To 2.: ION_RAMOFF_RTC System ON, No RAM retention, Wake on RTC 1.9 μA + 64 k RAM-Ret. 0.48 µA = 2.38 µA? Also have to add LFXO? -> 2.38µA + 0.25µA = 2.63 µA?

3.: First page sais: TX current 5.3 mA @ 0 dBm; Page 76 sais: TX current 7.1 mA @ 0 dBm. So is it correct to asume that the 7.1 mA is the real value?

4.: The datasheet has no values of TX and RX power consumption @ 0dBm and @ 2 Mb/s. Could you tell me the values?

Thank you!

[Stian Røed Hafskjold]

Sorry for the confusion. The RTC implies that the LF clock is running, and in the current consumption scenarios they've used numbers for the internal LF (LFRC). Sorry, this should have been specified.

So then you have:

1. SysON + RTC + LFRC = 1.2 + 0.1 + 0.6 = 1.9 uA
2. SysON + RTC + LFRC + 64k RAM = 1.2 + 0.1 + 0.6 + 0.48 = 2.4 µA
3. The radio itself consumes 5.3mA. When adding all the other peripherals needed to run the radio you get to 7.1mA
4. TX 2Mbps is the same as TX 1Mbps.

[FrankBi]

Dears,

How to measure 64K RAM‘s power consumption， that marked 0.48 uA， how to get it ？

Thanks.