Enable Integrated Circuit doubt

Thread Starter

josmA

Joined Jun 12, 2019
22
Hello,

I am trying to add the eFuse STEF01 IC from STMicroelectronics. I would like to use the enable/disable option to turn on and off the output to reduce consumption when I am not using the device (sensor). At the same time, I would like to use the Faul functionality to receive the alert in my microcontroller. The datasheet says "The EN/fault pin is internally pulled up to 5 V". I am confused about how I should connect this pin to the microcontroller, directly? Could this 5V damage the microcontroller (works at 3.3V)?
How do I manage the situation from the microcontroller programming perspective, as I guess the port pin needs to act as an input to receive the fault condition and as an output to disable the eFuse?

On the other hand, I would also like to use the PG (Power Good) function. Similarly, should I connect the output PG pin to the microcontroller directly? It needs a pullup resistor connected to the voltage input (20V in my case), is it safe for the microcontroller?
The datasheet says that high impedance at PG pin means the power is ok, low impedance -> not ok. what signal do I receive in the microcontroller for each case?

Sorry for too many questions. I guess this has to be pretty simple for someone used to it. Any help will be appreciated. Thanks!
 

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sghioto

Joined Dec 31, 2017
2,363
One way is shown below to isolate the two conditions.
The MCU Output line will shut down the E-Fuse.
The MCU Input line will detect the the Fault.
When the MCU Output is High the E-Fuse is shut down by Q2 going Low
When the E-Fuse detects a Fault the EN/FAULT line will drop down to 1.4 volts turning Q1 ON making the MCU Input High.

Note that when The MCU Output is High the MCU Input will also be High so you will need to take this into consideration in your programming.
1612720574347.png
A simpler version using an Analog Input on the MCU.
1612735183221.png
 
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