Request for ULD Library Support for VL53L3CX Distance Sensor

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Dear ST Team,

I am having difficulty finding the ULD library for the VL53L3CX chip. The complete library is too large for my chip's Flash memory, and the ULP library's ranging capabilities and accuracy do not meet my requirements. Could you tell me if there is a ULD library available for this chip, similar to the one provided for VL53L1? Thank you for your assistance.

[John E KVAM]

The easy thing to do here is to just buy the L1. It has the ULD you want. It is, however, more expensive.

But I can tell you a secret. The L3 is an L1 with the lens removed. So you can use the L1 ULD on the L3 - if you modify the function that checks the chipID. 

(Note that without the lens, the ROI functions really have no meaning so don't use those.)

If you do this, you will not get the range that the data sheet promises. Probably only get a couple of meters. 

(This is not encouraged, and you are kind of on your own if you try this.)

But if that is enough, then go for it. 

The VL53L4CD is our least expensive ToF sensor, uses a very small driver and has a range of 1.3 meters. It has a narrower Field of View (18 degrees vs 27 degrees) that some people like. You might consider that one.

- john

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Hello John,

Thank you for your reply. I think I may have misunderstood something. You mentioned that the VL53L1 is essentially a VL53L3 with the lens removed, not with something added. This raises a couple of questions:

1. If the VL53L1 is just a VL53L3 without the lens, why do they show different power consumption levels in their respective datasheets? 

2. What's the practical benefit of removing the lens from the VL53L1? Why would ST launch a version without a lens, and what's the design purpose behind this? I understand that without the lens, the range and accuracy would be reduced, but it must have other advantages to be offered as a separate product.

Thank you.

[John E KVAM]

1) The accuracy and the distance is a function of how many photons are returned. In order to reach the distance and accuracy numbers, we adjusted the timing budget to meet those target numbers. And the longer one ranges, the more power one consumes

The sensor will consume the same power - while it's ranging. Just range a little longer and you get more accuracy and perhaps more distance.

2) The practical benefit of the L3 is cost. That lens is not free. Some people cannot afford it.

As for why we did it, we are trying to have a product for every price range. 

Narrow FoV - go with the VL53L4CD (close distance) or CX.

Wider FoV - go with the VL53L3.

Or if you can afford a bit more, get the lens in the VL53L1X or the ultimate VL53L1CB.

Somewhere in there should be a sensor just right for your application.

- john