LIS3MDL Power Down Mode Issue

[SKund.1]

Hi,

We are using LIS3MDL in our application and current consumption in Power-Down mode is 0.2mA which is quite high but it should be 1uA as per the datasheet.

Any suggestion on why I am unable to achieve 1uA level as mentioned in the data sheet?

Regards

Siva

[Eleon BORLINI]

Hi Siva @SKund.1​ ,

it's indeed much higher than the declared Power-down consumption.

I believe it could be an issue related to the hardware configuration of the pins: could you please share the schematic of your application board?

For example, which is the configuration of the SDO/SA1 pin? Should be indeed an input without pull-up by default, but can you please check whether you have connected it to Vdd or GND?

-Eleon

[SKund.1]

Hi Eleon,

We are using adafruit module for testing purpose only and their schematic is shown below

SDO is connected to GND in our case.

Once we are happy with the current consumption then we are planning to add into our final project.

Regards

Siva

[Eleon BORLINI]

Hi Siva @SKund.1​ ,

it looks ok.

Did you measure the current consumption from the device Vdd only (without any other devices connected?)

And could you please unsolder the R2 resistor and connect the SJ1 solder bridge and check again the power down consumption (no SPI running, and register not configured, right?)?

-Eleon

[SKund.1]

Hi Eleon,

I haven't connected to any other devices, I modified as you suggested now I2C has stopped working.

Regarding SPI, I don't see a register where you can choose between SPi and I2C other than "CTRL_REG3 bit-3".

Regards

Siva

[Eleon BORLINI]

That's strange... it should be the I2C less significant bit of the device address (SA1)

What if you leave it unconnected?

By the way, except the fact that the I2C is not working, are you still experiencing overconsumption?

-Eleon

[SKund.1]

Now it's pulling 0.17mA current which is not a big difference. I reverted the hardware changes now I2C is back to normal.

Here are steps I am following:

1. Read Chip Id.
2. Perform Software Reset
3. Set XYZ in Low power mode
4. Set frequency 0.625Hz
5. Set full scale to +/- 4 gauss
6. Write INT_CFG register with 0X8D
7. Set Power Down mode

Is this correct?

[SKund.1]

Also, interrupt pin doesn't seems to trigger in power-down mode and single-conversion mode. Is this correct?

[Eleon BORLINI]

Hi @SKund.1​ ,

please note that the power down mode is basically the idle state.

In power down mode, the internal digital machine works at minimum level: you have no output and no interrupt.

The power down state is the state just after you power on the device with Vdd and VddIO, so before the "Read Chip Id" command. Which consumption do you measure in this case?

The minimum working state (with output and interrupts) is the low power mode.

Are you setting the power down with MD1-MD0 bits of CTRL_REG3 (22h) register?

You can also try setting also the LP bit of CTRL_REG3 (22h) register at '1'. As described in the datasheet p. 26:

If this bit is ‘1’, DO[2:0] is set to 0.625 Hz and the system performs, for each channel, the minimum number of averages

-Eleon

[SKund.1]

Hi Eleon,

I am measuring current consumption after "Set Power-Down mode" (Step-7), I did set MD1-MD0 bits to "10" and it's still pulling high current.

I tried even setting LP bit on CTRL_REG3(22h) and DO[2:0]-> "000" but I don't see any change on the current consumption which is a bit strange.

Regarding Power-Down mode, I was under the impression that the device will wake up from the power down mode if the threshold exceeds set value.

Now I am seeing 0.78mA in both Power-Down mode and in continuous mode. I am not sure what's happening.

Is there a way to check if the device is working correctly?

Regards

Siva