LSM303DLHC low-power and high resolution modes

[geometrikal]

Could somebody please explain what the LSM303DLHC low-power and high resolution modes do? The data sheet has very little information. Is it different from the older version LSM303s? What is the change in power consumption?

Page 15 has:

Low-power mode - BW(Hz) = ODR/2, Turn on time = 1ms
Normal mode - BW(Hz) = ODR/9, Turn on time = 7/ODR

I assume BW means bandwidth, but of what?

Page 15 also has:

LSM303DLHC provides two different acceleration operating modes, respectively reported as “normal mode” and “low-power mode”. While normal mode guarantees high resolution, low-power mode reduces further the current consumption.

and there is a high resolution enable bit in CTRL_REG4_A. But what does it do?

Thanks.

[JeremyT]

Hello.

Unfortunately, we do not really have any additional information about the LSM303DLHC beyond what is in the datasheet. In low-power mode, the frequency in which the data gets recorded is lowered and we observed the resolution decrease by 2 bits. The frequency at which the data rate can be set to is shown in Table 20. For normal operation (high resolution), you have to set CTRL_REG4[3] bit high.

- Jeremy

[geometrikal]

Thanks for the answer. Any idea if re-enabling high precision mode when in low-power mode works? I might have to do some experiments, will post any new info here.

Cheers

[JeremyT]

Table 8 on the datasheet suggests that it might not be possible to enable high precision mode while in low power mode, but I have not tried it. I am looking forward to your results.

- Jeremy

[geometrikal]

Here are the results:

Specified precision in datasheet: 16 bits

Low power, low resolution: 12 bits
Low power, high resolution: 12 bits
High power, low resolution: 14 bits
High power, high resolution: 16 bits

[JeremyT]

Thanks for posting your results! It looks like you cannot enable high precision mode while in lower power mode.

- Jeremy