Hall effect power draw

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Hi,  ok I’m getting closer.  I’m running a attiny3216 with a hall effect sensor.  The Hall effect wakes the AVR on interrupt , AVR runs the loop then goes back to deep sleep which gives me a very low power draw at any MHz I choose.  But the killer is the 2mA draw of the Hall effect while running and at sleep. Is there any way to reduce the draw of this sensor or do I need to find one with a lower draw.  Currently it is a 130NL sensor,  but I’ve tested a few and they are all about the same. 

Last Edited: Fri. Jul 9, 2021 - 03:50 AM
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A magnetic glass Reed draws nothing. Not as versatile as hall sensor though.

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Thank you fir the suggestion, but due to the requirements I have to use a Hall effect.   I did find a Texas instrument HES that draws less than half the juice.  But the strange thing, I am using the same sensir from another device and that device has a lower amperage draw, so I don’t know what I’m missing 

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is there nothing on power management of the sensor in the datasheet?

 

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There was similar discussion: how to reduce an IRR current. Idea was the same: apply the pulsed power, but nobody can guess how it will work.

The datasheets does not provide Power-up vs Output relations.
You may try 40ms first, then, on success, do reduce to 30 or 20ms. Of course, if 40ms per 1s suits your design or requirements. 

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I put your part number into digikey and no hall sensor is displayed, can you give the full part number, or better a link to the DS, please.

jim

 

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Try https://www.ti.com/lit/ds/symlin...

 

I think I got mine from LCSC

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You want to optimize low power consumption, but don't bother to think of providing a part number or schematic ?

 I am using the same sensir from another device and that device has a lower amperage draw

Sounds nice.  You can reduce the average power consumed if you hook the pin to the improved circuit, but without making the other connection---that's where the power is being drawn.

Try doing this and you will see what happens to the overall consumption.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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This looks like a good option for my project.  The one that was supplied to be has a 130NL on it, no other indicators,  I found it on a site but it was not a nice site like DigiKey.  It was a site in Taiwan and I could not read any of the specs but the photos were exactly what I have.  

 

avrcandies wrote:
You want to optimize low power consumption, but don't bother to think of providing a part number or schematic ?

 

Sorry newbie mistake, schematic included.   Could my problem be that I'm not regulating power to the circuit. I am worried about using a regulator that will cause more power loss that it saves.  I am hoping to reduce the power to 1.8v from the 3.3v to the circuit but I must keep my costs low by minimizing components and I need to extend my battery life to 90 days minimum.

(please forgive any incorrect terminology). 

Attachment(s): 

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Let the processor wake itself up, say, every 200ms (5 times a sec) use an AVR pin to power the hall, so it powers up, looks for something...if nothing to see, it goes back to sleep within a handful of microseconds. If something is seen, it stays on & does whatever is supposed to happen. 

..Now this means the field or magnet you detect can have a detection delay of up to 200ms.  If you are detecting a burglar is opening a door, that means you might get to sleep for an extra snore.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Thank you sir, This is not as critical as a burglar alarm, this system is for reading rpm's, missing a couple rotations is not critical, we are just looking for close.    This means I can increase the wake increments and sacrifice a couple rotations if it means battery life increases.

 

Should I run directly from the battery like in the schematic2 (see 2nd attachment) or should I reduce the 3 volts down to 1.8 volts, will this help lower the mA draw or will I lose more life than I gain.

Attachment(s): 

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this system is for reading rpm's

Unless the rpm's are very slow, wouldn't you need to wake up quickly....or if the timer wakes it up, then you could perhaps then see if it appears moving & if so stay awake longer to measure.

 

You schematic is nonsense...you will uses an IO pin , say PA2, or PB2, etc to power up the sensor, not "+"

 

  

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Ok, I’m learning as I go, I’ll be more specific.
 

the rpms are slow and it’s accumulating a total qty so losing a few clicks aren’t a big deal fir this project.   
 

so I’ll wake by the timer,  if the hall is changing I’ll continue counting until it stops,  then back to sleep.  
 

Would you like suggest minimizing the voltage to the 3216 to 1.8 volts to reduce the power draw.  Or would you go directly to the battery unrestricted?

Last Edited: Mon. Jul 12, 2021 - 05:21 AM
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MCU power consumption is likely to be a small fraction of the total if it is sleeping, at all. Decreasing the supply voltage to save power is often a loosing proposition and it is absolutely a looser if you use a linear regulator. With a linear regulator, you often waste more power in the regulator than what the MCU uses!

 

Jim

 

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Thanks. 

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ka7ehk wrote:
With a linear regulator, you often waste more power in the regulator than what the MCU uses!

 

True - but sometimes it's the only way to meet the EMI regs. At least micropower regulators don't loose to many amps down the ground terminal. When investigating power supplies we found pretty much a complete absence of switching parts which could supply 3v3 but take more than 6v in, which is not healthy given that at the currents we were using - a couple of hundred microamps - a battery of four C cell alkalines will hold in excess of 6v4 for over three months (and if the customer decided to use the 'obviously superior' lithium cells, it started at 7.8v and stayed there for months).

 

Neil