MQ-7 CO sensor easyC heating cycle not implemented as datasheet specifies

TECHNICAL SUPPORT Sensors & Modules
1

Customer:

The MQ-7 datasheet specifies that for proper operation, the sensor should be heated at 5V for a period, then lowered to around 1.5V for accurate CO readings, then the cycle repeats. Looking at the schematics for the easyC breakout, I don’t see how this is possible. Is the heater always on at 5V with this board? If so, wouldn’t that provide suboptimal readings?

Originally submitted via email support on 22 August 2025. Migrated to the forum for community visibility.

2

Soldered Support:

You are correct about the two heating states required for the MQ-7. With the current design, it is unfortunately not possible to provide the proper heating cycle as described in the datasheet. This is a design error, and we have forwarded this information to our team.