Intrinsic safety smart sensor

Thread Starter


Joined Apr 16, 2018
Hi All,

I have to design and implement a smart sensor for instance a magnetic odometer with "Intrinsic safety" parameters. That means
the voltage should not exceed 1.8v and the current is limited to 2uA.
A protection circuit barrier should be placed between Master and slave to guarantee these parameters as shown in the block diagram below.

ESP1 16-Apr-18 15.26.gif
MOD: Included your image.
The master is a MK22fn512vlh12 kinetis MCI have to find out an appropriate slave MCU which consumes less than 1.8v (preferably less than 1.7 v) in active mode.The clock speed should be
fast enough to deliver data each second (I believe is not an issue), the rest of the time the slave MCU can be in sleep or another low-consumption mode.
The key point is to guarantee the correct operation under the safety parameters.

The communication protocol intended to be implemented is 1-wire communication because it is desired that the Master only uses one pin to record the data coming from the odometer. However 1-wire protocol is not a must and other options can be considered.

The implementation shall be adaptable for multi-slave operation.

I am particularly confused about the current constrain in regard to the MCU current consumption.
Does the slave MCU have to operate with max 2uA? or
The current which arrives to the slave MCU shall be no more than 2uA?.
Can a MCU generate more than 2uA in order carry out its functionalities?. If so can still the system be considered as Intrinsically safe?

Which MCU could suit these specifications?

Is 1-wire protocol a good approach?. Are there good alternatives?

As you can see the kind of questions shows a lack of knowledge and inexperience regarding this topic.
I would appreciate very much your comments and also some references where to find out more answers about this topics.

Thanks in advance for your help.
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