VL53L5CX: Entering in LP mode

[Balkana]

When powered with 3.6V (both AVDD and IOVDD), VL53L5CX does most of the time does not enter LP mode (via the I2C command).

At 3.5V most of the time LP mode is entered correctly, and rarely - incorrectly. 

At 3.4V, LP mode is entered always correctly.

According to the datasheet, all of these are valid combinations.

Searching in the documentation so far does not explain the results.

Could anybody shed some light on the subject (else, it will be needed to modify the hardware)?

[John E KVAM · Accepted solution]

In the datasheet is:

this says that the max rating is 3.6.

IN the paragraph above is the line:

Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

I'm going to postulate that we set that max because we started to see failures at 3.6.

Electrically, once you get the IOVDD too high, you start seeing I2C read/write failures and it's obvious in your test, but I'm thinking lots of other read/write failures will occur that are not so obvious. 

Try to find a way to limit at least the I2C. It's tolerant down to 1.6 volts.  

- john

[Balkana]

Thanks a lot, John - all clear now. 

You are right, other anomalies (mainly increased consumption) are present at higher voltage, despite functionally all seems fine.

To give more details: product is powered with a single cell Li-Thionyl battery, which never exceeds 3.6V, therefore according to the datasheet - it looked fine. Now it is clear that an LDO will be needed.

Could you please advise for the voltage selection for safe operation point and least possible consumption, assuming single power supply for AVDD and IOVDD, to try to maximize the battery life.

I would like to take advantage of the feature mentioned here:

https://community.st.com/t5/imaging-sensors/vl53l5cx-ultra-lite-driver-uld-enable-disable-internal-charge/m-p/89694

So I guess maybe the best value to select is 3.3V.

Best regards,

Marin