BME680/688 heater temperature range

[GaryM]

I notice that in the BME680 and BME688 data sheets there is a statement that the gas heater is typically set to temperatures of 200 to 400 degrees C, but I can't find anywhere that specifies limits. I infer that the heater can be programmed as low as 100 degrees as there is an example of "a standard heater profile" in the BME688 data sheet (figure 1) that shows heater temperatures as low as 100 degrees.

The question is how low of a temperature can we set and how high of a temperature can we set without compromising the measurement or damaging the heater?

Thank you, Gary Marks

[BSTRobin]

Hi GaryM,

If you want to use a custom heater profile, based on our experience, for temperature, it's better to set from 200 to 400, and for duration, it's better from 30 to 4032ms. Refer to document https://www.bosch-sensortec.com/media/boschsensortec/downloads/application_notes_1/bst-bme688-an001.... to set temperature and duration of heater profile.

[GaryM]

Hello BSTRobin,

When you say it's better to set from 200 to 400, can you explain the criteria for "better"? How exactly is it better?

I did look at the app note that you referenced. There is nothing in it that deals with appropriate heater temperature ranges. However, it did contain several examples that go outside of the range of 200 to 400. Specifically, it shows several heater profiles that use a heater temperature of 100. So I don't understand the 200 degree minimum. So I'm going to assume that 100 degrees is OK.

So then let me restate my original question. How high can I take the heater temperature before I cause damage or loss of accuracy? The target resistnace regesiter allows temperatures approaching about 830 degrees. Can we actually safely program the temperatuer to that level?

Thank you again,

Gary Marks

[BSTRobin]

Hi GaryM,

We have conducted internal testing and suggest setting the temperature to 200-400 degrees, but we do not recommend setting the temperature to exceed 400 degrees.

In BME688 data sheet: