Author Topic: high moteino r4 power consumption during sleep at 3Vin [answered]  (Read 6551 times)

TacticalSnack

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At the risk of raising a solved topic, I'm powering a bare moteino r4 at 3 VDC from a bench supply and running the sketch below. I have a resulting current draw during sleep of 73ľA which from data sheets and others' experiences is quite high. Side note, the moteino r4 has had the flash chip removed in the attempt to discover why the current was so high.

Code: [Select]
#include <LowPower.h>

/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.
 
  This example code is in the public domain.
 */
 
int led = 9;

void setup() {               
  pinMode(led, OUTPUT);     
}

void loop() {
  LowPower.powerDown(SLEEP_4S, ADC_OFF, BOD_OFF);
  digitalWrite(led, HIGH);
  delay(10);
  digitalWrite(led, LOW);
  delay(990);
}

I also tested a second moteino with flash chip using pretty much the same sketch but putting the flash to sleep with the result of a 1 or 2 ľA increase from the previous test. I have also confirmed readings with a second meter. I'm pretty much out of ideas as to why my current draw is so high.
« Last Edit: November 15, 2014, 12:50:14 PM by Felix »

Felix

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Re: high moteino r4 power consumption during sleep
« Reply #1 on: October 09, 2014, 08:50:58 AM »
I would say you're way below spec at 3V. It might work but I don't know exactly how the regulator will handle that.
Give it at least 3.5V on the VIN pin. Sounds like there is nothing else attached to the board. But if not, you would need to power down anything else attached to the Moteino (any sensors etc, if any).
You also need a good true RMS multimeter to get a ballpark of what's going on.
And yes there are other topics in the forum where this subject was discussed, worth a search.

TacticalSnack

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Re: high moteino r4 power consumption during sleep
« Reply #2 on: October 09, 2014, 09:22:22 AM »
Thanks, Felix. Forgot to consider 3VDC is outside the safe operating area for 328P when running at 16 MHz. I guess I'll be learning about fuses sooner rather than later. I will try 3.5V on VIN asap and update.
So I gather my Extech EX330's not going to capture a good reading? I also put 3V to the 3v3 pin to bypass the regulator. I have the moteino on a breadboard with nothing else attached (moved moteino to another spot on the breadboard and even tried another breadboard altogether).

I've noticed the following posts but have failed to discover a solid reason ...
Power Saving Techniques and Libraries - https://lowpowerlab.com/forum/index.php/topic,286.0.html
Moteino draws excessive current - https://lowpowerlab.com/forum/index.php/topic,494.msg2777.html#msg2777
Moteino v2 sleep mode: is 0.17 mA at 3.3 ... - https://lowpowerlab.com/forum/index.php/topic,166.msg639.html#msg639

TacticalSnack

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Re: high moteino r4 power consumption during sleep
« Reply #3 on: October 10, 2014, 09:34:21 PM »
Yep, as you suspected, VCC was too low. I started reading around 6ľA when 3.5V was applied.

Felix

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Re: high moteino r4 power consumption during sleep
« Reply #4 on: October 11, 2014, 10:06:55 AM »
Right, so you always want to supply at least 3.3V + the dropout voltage of the regulator which by the way is a very low dropout regulator.
If you look at the datasheet, there are some (Dropout V vs Load A) graphs. If the load is very small the dropout is almost 0. So you should be able to verify this if you supply anywhere above 3.3V.
As the load increases the dropout will also increase so your VIN should allow some room for that.
Conversely, as the load increases, your concern for very low power decreases.

Datasheet here: http://ww1.microchip.com/downloads/en/DeviceDoc/22049f.pdf

emjay

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Re: high moteino r4 power consumption during sleep
« Reply #5 on: October 11, 2014, 11:03:53 PM »
When operating at or below the dropout voltage, an effect that is often not shown on the LDO datasheets is an increase in quiescent current. The error amplifier is doing its best to turn on the pass element harder, but to no avail once the lowest Rds is reached.  The overdrive however kicks up the current consumed by the LDO itself, leading to a rise (often substantial in μA) in total current drain from the source.

The 'fix' is as Felix describes - avoid this operating region if you are seeking the lowest sleeping draw.

TacticalSnack

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Re: high moteino r4 power consumption during sleep
« Reply #6 on: October 17, 2014, 04:42:47 PM »
Thanks emjay. I definitely noticed that bump in power consumption when I was too low, hence the confusion.

Lensdigital

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Re: high moteino r4 power consumption during sleep
« Reply #7 on: November 08, 2014, 09:32:34 PM »
When operating at or below the dropout voltage, an effect that is often not shown on the LDO datasheets is an increase in quiescent current. The error amplifier is doing its best to turn on the pass element harder, but to no avail once the lowest Rds is reached.  The overdrive however kicks up the current consumed by the LDO itself, leading to a rise (often substantial in μA) in total current drain from the source.

The 'fix' is as Felix describes - avoid this operating region if you are seeking the lowest sleeping draw.
I'm having same issue, but must power it by 3V coin cell...  Would replacing MCP1703 with a 3.0V version solve issue with quiescent current?  Also I'm running ATMega328p chip at 8Mhz so it's completely within specs...
 
Check out my hand made open source Xronos Alarm Clock!
http://www.xronosclock.com

emjay

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Re: high moteino r4 power consumption during sleep
« Reply #8 on: November 09, 2014, 08:19:10 AM »
@LensDigital,

Unfortunately no, since the coin cell is nominal 3V, there is again no head room for a 3.0V LDO.
For lowest "waste" consumption, dispense with the LDO completely unless you have some sensor attached that really needs a stable supply - with adequate decoupling, the ATMega and RF module don't care. You will see this technique over at http://www.digitalsmarties.net/products/jeenode-micro
Note that the LDO must be completely removed, just bridging its Vin to Vout or leaving Vin open circuit with power on Vout will still have a quiescent drain.
« Last Edit: November 09, 2014, 08:23:03 AM by emjay »

ned

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Re: high moteino r4 power consumption during sleep at 3Vin [answered]
« Reply #9 on: December 27, 2014, 09:07:10 PM »
Hi all,

I am having problems minimising my current draw in sleep mode. I'm new to this so I guess I've made a simple mistake, but can't for the life of me find what I've done wrong. I think I've read everything on this forum on similar issues. Details of my test below:

-Moteino R4, with RFM69W, no flash, no peripherals attached
-test code: as for the OP TacticalSnack. I also included radio.sleep()
-5V to Vin (I also tried 3.5V to Vin, with no change in current)
-equal results with two identical new Moteino R4's

I can't get the current draw below 1.5mA in sleep mode. Any ideas?

cheers

Felix

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Re: high moteino r4 power consumption during sleep at 3Vin [answered]
« Reply #10 on: January 03, 2015, 10:10:07 PM »
Ned - how are you measuring current?

ned

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Re: high moteino r4 power consumption during sleep at 3Vin [answered]
« Reply #11 on: January 03, 2015, 10:32:40 PM »
I measured the current using the ammeter of a multimeter.

To double check this value I also measured the voltage drop over a 10 Ohm resister in series, which was ~15mV. In this case there was 5V applied to Vin so there was still ample voltage at Vin.

Felix

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Re: high moteino r4 power consumption during sleep at 3Vin [answered]
« Reply #12 on: January 04, 2015, 04:27:29 PM »
The reason I asked is because I've had others measure it "with a multimeter" and after some time chasing rabbits in wonderland it turned out they did it with a $10 chinese DMM in AC mode :)
But it "sounds" like you are doing it right, just good to check before we move on.
As long as you put everything to sleep the current should be in the 10 uA range or thereabouts. I assume your atmega, regulator and radio are still in intact condition and have not been shorted or overdriven in any way. Those may be common causes for high current. Code would be nice to be included, hard to chase other code in other posts you know.

ned

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Re: high moteino r4 power consumption during sleep at 3Vin [answered]
« Reply #13 on: January 04, 2015, 06:34:01 PM »
Understood, well I used a TENMA 72-7720, so it's not very expensive at ~$35 but it should be able to measure below 1mA. I've tried this with a brand new moteino with equal results. The code follows:

Code: [Select]
#include <LowPower.h>
#include <RFM69.h>    //get it here: https://www.github.com/lowpowerlab/rfm69
#include <SPI.h>
#include <SPIFlash.h> //get it here: https://www.github.com/lowpowerlab/spiflash

/*
  Turns on an LED on for 10ms, then goes into sleep mode for 4s, repeatedly.
 */

#define NODEID        2    //unique for each node on same network
#define NETWORKID     100  //the same on all nodes that talk to each other
#define GATEWAYID     1
//Match frequency to the hardware version of the radio on your Moteino (uncomment one):
#define FREQUENCY   RF69_433MHZ
//#define FREQUENCY   RF69_868MHZ
//#define FREQUENCY     RF69_915MHZ
 
int led = 9;
RFM69 radio;

void setup() {               
  pinMode(led, OUTPUT);     
  radio.initialize(FREQUENCY,NODEID,NETWORKID);
  radio.sleep();   //stops led blink
}

void loop() {
  LowPower.powerDown(SLEEP_4S, ADC_OFF, BOD_OFF);       //1.5mA measured
  //LowPower.idle(SLEEP_4S, ADC_OFF, TIMER2_OFF, TIMER1_OFF, TIMER0_OFF, SPI_OFF, USART0_OFF, TWI_OFF);      //3mA measured
  digitalWrite(led, HIGH);
  delay(10);
  digitalWrite(led, LOW);
}

Felix

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Re: high moteino r4 power consumption during sleep at 3Vin [answered]
« Reply #14 on: January 04, 2015, 08:53:37 PM »
Can you tell me what is the current reading when you have the arduino LED blink program running (ie when nothing is put to sleep explicitly)?
« Last Edit: January 04, 2015, 09:49:27 PM by Felix »