VL6180X VCSEL Light Depreciation Characteristics and Impact Analysis

[Andy_Chien]

I am currently working with the VL6180X proximity sensor and would like to inquire about its long-term performance characteristics:

      1. What is the expected Light/Luminous Depreciation time frame for the VL6180X's VCSEL source? Could you                provide any data regarding its lumen maintenance curve or L70/L50 specifications?
     2.How does Light/Luminous Depreciation affect the sensor's performance over time?

        Specifically:
                 1. Does it primarily manifest as a reduction in return signal rate?
                 2. Are there any observable changes in measurement accuracy?
                 3. What are the typical indicators that Light/Luminous Depreciation has occurred?
      3. Are there any recommended compensation strategies or calibration procedures to account for VCSEL aging                 effects in long-term deployments?
This information would be valuable for our reliability assessment and long-term performance predictions.

Thank you for your assistance.

[John E KVAM · Accepted solution]

Andy - 

I could answer all that for you, but I don't think you want to go this way. 

Due to sourcing issues, we were forced to quit making that sensor. Currently its NRND - not recommended for new designs. 

The sensor had a 10-year run, which is pretty good. But we bought those filters, and we can no longer get them. 

May I suggest you go with the VL53L4CD ToF sensor and a VD6283 ALS chip. 

I know having 2 devices instead of one is more complex, but in those 10 years we've done a lot. 

The VL53L4CD is a better ToF sensor, and the VD6283 is a better ALS. So you get a better product. 

- john

[Andy_Chien]

If we don't need a sensor that measures such long distances and only need to measure ranges less than 100mm, are there any recommended sensors? Thank you.

[John E KVAM]

There are two types of problems Time-of-Flight solves. Some people want the really long distances and are always looking to 'see' farther. And then there are the short distance guy who only need a little. 

So there are two versions of the VL53L4CD - the CD (Close Distance) is the one you want. It's our best. Granted it can 'see' to 1.3 meters, but it's pretty darn good down to 1cm. Below about 7mm its accuracy is questionable. You know something is really close, but is it 3, 5 or 7mm? 

There is an evaluation kit - the P-Nucleo-53L4A1. It's $56 and with it, you can prove the sensor works before you invest a lot of time.

- john

[Andy_Chien]

Thank you for your response. We will switch to using the VL53L4CD, but I have a question. From what I know, while the VL6180X has non-volatile memory, it doesn't actually allow users to write data to it. Does the VL53L4CD provide accessible memory addresses where we can write data? Thank you.

[John E KVAM]

Writing to the non-volatile memory would involve new power rails and a whole bunch of documentation that we didn't want to get into. Besides it would make it far too easy for you to ruin the sensor. And then there is the issue of potentially making the chip less eye-safe. Locking that chip up was one of the constraints of the Class 1 eye safety certification. 

We opted to just not go there. Too hard, too costly for you, and potentially dangerous.