The best way to save energy in an application

RE: The best way to save energy in an application

user113102 — Thu, 16 Jun 2022 07:49:29 GMT

Hi Jared,
About regulator I have some confusions about this topic
I follow this thread but It hard to understand

1. What is the difference between external DC/DC converter and internal DC/DC converter ?
2. May I supply 1.8v voltage for my nRF saving energy working?
3. My custom board don't have LC so It seems can not enable DC/DC converter ? What is the alternative solutions?
4. DC/DC is automatically enabled when voltage goes below 2.1V => LDO is disabled and vice versa when voltage goes up?

RE: The best way to save energy in an application

user73165 — Wed, 15 Jun 2022 07:12:42 GMT

Hi,

[quote user="John12"] how and when I should enable DC/DC converter ? Any blog post ?[/quote]

If you're using the Softdevice then you can use the SD API by calling sd_power_dcdc_mode_set() in the beginning of main().

[quote user="John12"]. what is the advantage when I make app_timer use external external crystal ? how can use external crystal? I attached my sdk_config.h please check for me.
May It here ? What is RC, XTAL, SYNTH ?[/quote]

The external low frequency crystal has a lower run current then the RC oscillator. Thus it will consume less current. See the clock section in the product specification for a description of the different LFCLK sources.

regards

Jared

RE: The best way to save energy in an application

user113102 — Tue, 14 Jun 2022 17:11:12 GMT

Hi Jared,
I can't find any schematic from this module
But I confirm that is external crystal.
So please suggest for me:
1. how and when I should enable DC/DC converter ? Any blog post ?
2. what is the advantage when I make app_timer use external external crystal ? how can use external crystal? I attached my sdk_config.h please check for me.
May It here ? What is RC, XTAL, SYNTH ?
Thank for your reply.
I'm new at this topic so your reply help me a lot.

// <o> NRF_SDH_CLOCK_LF_SRC  - SoftDevice clock source.

// <0=> NRF_CLOCK_LF_SRC_RC
// <1=> NRF_CLOCK_LF_SRC_XTAL
// <2=> NRF_CLOCK_LF_SRC_SYNTH

#ifndef NRF_SDH_CLOCK_LF_SRC
#define NRF_SDH_CLOCK_LF_SRC 1
#endif

RE: The best way to save energy in an application

user73165 — Tue, 14 Jun 2022 12:18:18 GMT

Hi,

There are two internal regulators on the nRF52833 that regulates the supply down to the system voltage in two stages. The internal regulators can either use an internal LDO or a DCDC for each step. Using the DCDC requires external inductors, but the benefit of using DCDC is that it's more power efficient.

It seems like it has an external LFXO crystal, do you have the schematics?

The app timer would automatically use the external low frequency crystal, if it's chosen as the LFCLK clock source in the sdk_config.h file of your project.

regards

Jared

RE: The best way to save energy in an application

user113102 — Tue, 14 Jun 2022 08:02:36 GMT

Yes, I have external components for DCDC. But I think it only used for convert 4.2v into 3.3v to compatible with module. What is other functions of DCDC converter ??
I got an sentence "enabling and populating the DC/DC converter" when I read blog post you suggested. But I have some confusions about this. Seem DC/DC converter like a peripheral. How can I "enabling and populating the DC/DC converter" ? By coding ?

I researched that there is an regulator that is LDO. What is the difference between them ?

Here is the module I used. It contained external LF crystal ? I'm using app_timer. How can I use external LF crystal like you suggest ?

RE: The best way to save energy in an application

user73165 — Tue, 14 Jun 2022 07:39:42 GMT

Hi,

Does your custom board have external components for the DCDC regulator? Do you have an external low frequency crystal?

regards

Jared

RE: The best way to save energy in an application

user113102 — Mon, 13 Jun 2022 16:22:28 GMT

Hi Jared, thanks for useful confirm
Please explain for me more detail. I new at decrease TX power, DCDC and external LF crystal. Please give me an example. I'm using an custom board developed by my partner, I only dev firmware so I'm not specialized at hardware.

RE: The best way to save energy in an application

user73165 — Mon, 13 Jun 2022 10:49:20 GMT

Hi,

These are all very good measures for low power. For the SAADC you can follow our low-power SAADC example which uses the RTC to schedule samples, see this. The logger should definitely be disabled if you want to have low current consumption. For the BLE you can decrease the TX power, use DCDC and external LF crystal.

Here is a blog post about optimizing power on nRF52.

regards

Jared