ISO 124 - Can I use the 9V VCC's ground for stage 1 and stage 2? Can i use only one battery on my circuit and iso 124?

Hello Guillermo,

No, you cannot use a single supply source for the ISO124 input and output stages if you want to maintain galvanic isolation between the stages. Voltage regulators will not provide galvanic isolation. The MC34063A, a boost/buck regulator, can generate a supply of the opposite polarity but again it will not provide the needed galvanic isolation.

You have the options of using separate batteries for the input and output stages, or use isolated high-voltage DC-DC converters as your teacher suggested. The latter tends to be quite expensive; especially, if you need to kilovolts of isolation between the input and output stages.

Regards, Thomas

PA - Linear Applications Engineering

Hi Guillermo,

For obtaining a -9V power source from a +9V battery you should use an isolated DC/DC. Texas Instruments have some references to solve this problem, but I don't now if it is possible to found a reference for 9V, maybe 12V or 5V are more standard versions.

However, I have one doubt about the circuit. You use the schematic to isolate the signals from the stage one form the stage 2. But if the power source (+9V, GND and -9V) are the same for the stages1 and 2... the isolation is not complete. You may break ground loops, but you do not have isolation between stages. If you want to use different power sources for both stages, you should use a DC/DC converter en each stage (and a battery in each stage).

I hope this information it is useful for you.

Best regards,

Iván

Thank you Thomas for your answer about ISO124! 

I was searching the internet for the high-voltage isolated DC-DC converters and I found several references, but in my country Colombia are not, I am interested in import as the need for a project soon, do you know some reference to isolated high-voltage DC-I serve DC converters 9v => 9v please! And if it can import, please Thomas! I need it! 

Thank you Ivan!

I can use only one battery, i could use 9v or 12v too, i was searching the internet for the high-voltage isolated DC-DC converters and I found several references, but in my country Colombia are not, I am interested in import as the need for a project soon, do you know some reference to isolated high-voltage DC-DC converters, 9v=>9v or 12v => 12v, in texas instruments or other, please! And if it can import, please, i need import this Ivan.

Regards from Bogota, Colombia

I can use only one battery, 9v or 12v, it´s for a project small and portable device that i'm doing. Do you know some reference to isolated high-voltage DC-DC converters, in texas instruments or other, please! And if it can import, please.

Thank you Jayant

Hello Guillermo,

Here is just another idea to think about: In 1991 we released the TLE2426. This device is called "The Rail-Splitter". You can use it to generate a voltage in the middle of your supply voltage. If you are using a 12V battery you could use this device to generate a 6V voltage. If you use this 6V voltage as "GND" you have a +6V and a -6V voltage in your system. This +/-6V supply can be used to supply the ISO124.

What do you think about this?

Thomas

Hello Guillermo,

Take a look at the DCP010115 web page at:

http://www.ti.com/product/DCP010505DB

This is one product amongst a family of HV, isolated DC-DC converters. Note that none of them have a 9V input voltage so may need to apply a different level, or down regulate to 5V. There is a place on the web page where you can request samples. I don't have much experience shipping samples abroad, but it  would seem that samples would be provided from a source where importation into a particular country could be accommodated.

Regards, Thomas

PA - Linear Applications Engineering

Thank you so much Thomas Kuehl!

This one is the converter I need, I hope now to continue with the import procedure, I hope to have great success in this step, I saw the datasheet and if I serve, I will make some changes to the circuit to the entrance to dcp010505db, thomas if you know as can be imported into Colombia I recommend a lot please!

Regards from Bogota, Guillermo