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ISO6740-Q1: Isolator for 12/24V signal

Danilo A.
Mastermind 26550 points
Part Number: ISO6740-Q1
Other Parts Discussed in Thread: ISO1212

Hi Team,

Our customer is looking for a 4-channel automotive isolator to determine if a 12V/24V signal is on or off. 

For example:
- If the break light of the car is on, the voltage rises to 12VDC.
- Their MCU will determine if the break light turned on.

They want an extra layer of protection with galvanic isolation between the break light of the car and the MCU input.
He needs a 0-reverse / 4-forward isolator, unfortunately, we don't have this type of device from our product line hence he will use the ISO6740-Q1 in the reverse orientation.
The typical application circuit shows that VCC1 and GND1 are connected to the same power source of the MCU. While VCC2 and GND2 are connected to the output of the isolated power supply.
In the customer's application, he will connect the VCC1 to the isolated power supply while VCC2 will be connected to the power supply of the MCU.

Is this application possible?
Regards,
Danilo
  • +1
    TI__Mastermind 19240 points

    Hello Danilo,

    Thank you for your question. Yes, it is perfectly fine to use the ISO6740-Q1 or any digital isolator in the reverse orientation. As long as VCC1/GND1 and VCC2/GND2 are connected to an isolated power supply the isolator will work as expected.

    Additionally, the ISO1212 may be a good alternative device for this kind of application. The ISO1212 is designed specifically to isolate 12/24V signals and does not require any additional power supply on the field/input side other than the input signal itself. There currently is not a Q1 qualified version of this device, but if a Q1 qualification is not a requirement, the ISO1212 would be another option.

    Regards,
    Darrah