IIS2DH current consumption

[Ranjith Ravindra Shanbhag_2]

Posted on January 08, 2018 at 16:39

Hello,

I am using IIS2DH to work for my application. But the problem rises when I measure the current it is consuming. At 25Hz with 40ms INT2 duration and Low Power Enabled with all axis, I am observing a current a current of 500uA which is not according to what mentioned in the data sheet of IIS2DH. The configuration is shown below:

CTRL_REG1: 0x3F

CTRL_REG4: 0x20

CTRL_REG6: 0x20

INT2_CFG: 0x04

INT2_THS: 0x05

INT2_DUR: 0x01

The above configuration works perfectly for my application. However, it is consuming a lot of current. Am I missing something? Please help.

Also, could anyone explain to me as to how BOOT_I2 bit on  CTRL_REG6 work ? what is its function? Where can i find information about it? 

#iis2dh

[Miroslav BATEK]

Posted on January 08, 2018 at 16:47

Concerning the current consumption, can you please share the schematic?

The BOOT_I2 bit in CTRL_REG6 allow to see boot status on the INT2 pin, basically if you enable this bit the INT2 pin will be high during sensor boot-up and goes low after that.

[Ranjith Ravindra Shanbhag_2]

Posted on January 08, 2018 at 18:07

Hello Sir,

There is not much in the schematic. I just have the STEVAL-MKI168V1. connected to TI-Launchpad CC2640 . I have the launchpad powered on using a battery. The battery +ve terminal is connected to one terminal of the Ammeter(uA) and from the other terminal it is connected to the Launchpad. The Launchpad has 3.3V port from which the STEVAL-MKI168V1 is connected. The TI - Launchpad configures the accelerometer and enters shutdown mode.

Regards

[Miroslav BATEK]

Posted on January 08, 2018 at 18:41

Can you please measure the current consumption only of the sensor, connect the ammeter between 3.3V port on Launchpad and the VDD + VDD_IO of the sensor.

According to your description it seems you are only assuming the current is flowing into the sensor and the current consumption of the Launchpad is negligible.

[Ranjith Ravindra Shanbhag_2]

Posted on January 08, 2018 at 18:56

Hello Sir,

Thank you for the quick reply. I did the changes as you mentioned. I am getting now around 100uA as the current. Is there something else that I am doing wrong here ?

Regards

[Miroslav BATEK · Accepted solution]

Posted on January 09, 2018 at 09:10

Yes, there is. If you connect the SA0 pint to GND there is additional current consumption cause by internal pull-up on this pin. So you can connect this pin to VDD_IO and you will rid of this current. 

[Ranjith Ravindra Shanbhag_2]

Posted on January 09, 2018 at 17:34

Hello Sir,

It is consuming upto 4uA now. Thank you for helping me.  

[Arpan Patel]

Posted on January 10, 2018 at 04:58

Hi Miroslav, on my board, the SA0 pin is floating which means there is no connection either to VCC or GND. So, is it affect current consumption or is it fine? Can you please provide comment on this query.

[Miroslav BATEK]

Posted on January 10, 2018 at 09:49

If the SA0 pin is let floating there won't be any additional current through internal pull-up, but this is not recommended configuration. The pin should be polarized (connected either to VDD_IO or to GND).