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is ADG1406 compatible with 24V systems?

Hello;

I am working on Truck OBD communication systems.

I designed a prototype card and used ADG1406 for get communication with Truck's different communication pins. I added "multiple TVS"s for protect to MUX's pins.

I use battery voltage 24V for ADG1406's Vcc.

One of the truck pin has 24V voltage. It is not battery voltage pin. And also it is not communication pin. I don't know purpose of that pin.

Whatever;

When the vehicle's ignition is off, that pin stays 0V.

When the vehicle's ignition is on, that pin jumps 24V.

I tried two methods:

1-)While ignition is off, i plug the card to OBD socket "then i open the ignition" and i don't have any problem.

2-)While ignition is on, i plug the card to OBD socket and that pin burn the ADG1406's  connected switch pin. After that ADG1406 doesn't work anymore and warming up fastly.

I designed new card and i added "resettable PTC fuse" to that pin.

While ignition is on, i plug the new card to OBD socket and that pin burn the ADG1406's  connected switch pin and PTC fuse activated. After that ADG1406 works except that pin.

In datasheet, it says:

"ICs capable of 33 V operation"

So what is the problem?

Parents
  • Hi;

    ####

    I recommend the ADG5206 as alternative.

    ####

    I bought 1000 pieces of this chips. So i can't give up

    ####

    What is the breakdown and clamp voltage of the TVS used?

    ####

    http://www.semtech.com/circuit-protection/esd-protection/sms24/

    Vbr=26.7V

    Vc=40V

    ####

    If you will have a 24V input on your switch input without power, then I would recommend that you use series R to limit current to <30mA range and place Schottky diodes to the supplies.

    ####

    I already placed Schottky diode to the supply. I placed 100-1000 ohm resistor like you said and it fixed the problem. Normally I have to place 1K for limiting current to <30mA range. But it causes another problem at another vehicle. So i placed 100 ohm resistor. I am still testing.

    Thanks for help.

Reply
  • Hi;

    ####

    I recommend the ADG5206 as alternative.

    ####

    I bought 1000 pieces of this chips. So i can't give up

    ####

    What is the breakdown and clamp voltage of the TVS used?

    ####

    http://www.semtech.com/circuit-protection/esd-protection/sms24/

    Vbr=26.7V

    Vc=40V

    ####

    If you will have a 24V input on your switch input without power, then I would recommend that you use series R to limit current to <30mA range and place Schottky diodes to the supplies.

    ####

    I already placed Schottky diode to the supply. I placed 100-1000 ohm resistor like you said and it fixed the problem. Normally I have to place 1K for limiting current to <30mA range. But it causes another problem at another vehicle. So i placed 100 ohm resistor. I am still testing.

    Thanks for help.

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