HCSR501 PIR sensor power consumption

Using Arduino Sensors
#1

I am a newbie so please excuse my dumb questions.

I am trying to calculate the expected power consumption of an Uno R3 running a simple script that polls a PIR sensor every second or so. I know a full Uno board uses roughly 50mA (250mW).

I have also seen someplace that the HCSR501 PIR sensor uses at most (when it is active and detecting a "body") 150uA.... or 0.150mA

Is this right? Is the power consumption of the PIR sensor in worst case scenario (on and active all the time, not idle ever) 0.3 PERCENT of what the Uno board uses?

I am just trying to make sure I am reading and understanding the data sheet right (still new at this).

Thanks for any and all help.

#2

Post a link to the data sheet.

#3

I am not sure if I read it correctly... thus not sure if the values I am using are correct.

#4

The data sheet says “current consumption 65 mA”, which is most certainly not correct. That may be the maximum current on the output line.

Below, it says, “static current consumption < 50 microamps”, which is about right for a product intended to be battery powered.

#5

Last time I bench-tested one of those (there are many variations), I measured ~70uA when idle.
Leo…

#6

Everyone: thanks!

Wawa: do you happen to remember the active power consumption? I am going to use that figure for my “worst case scenario” calculations. Thank you!

Sam

#7

SamBrownADK:
Wawa: do you happen to remember the active power consumption?

If you connect the PIR output to a digital input pin, then active should be the same as idle.
Worst case could be 2-3mA, e.g. when you drive the base of a transistor or a LED with the PIR output.
Leo..

#8

Leo:

Thanks... 3mA is small potatoes to 50mA or so... so i can ignore 6% of power. Changes in out door temp, etc would mask it any way. Its to be a remote outdoor battery driven device.

#9

3mA is not "small potatoes" for a battery powered project, and 50 mA is completely unworkable, unless you are happy changing batteries every couple of days.

Instead of an Uno, use a "bare bones" setup, or very easily remove the LED and regulator from a Pro Mini, and follow this excellent low power tutorial. Such a setup can run for a couple of years on 2xAA batteries.

#10