Dual Rail Supply for IR2104

[Amr Wael]

Hello ,
I wonder if it's possible to supply IR2104 with -12V while connecting it's ground (COM) to -24V in order to achieve a vcc of 12V relative to zero ground ?
I tried simulating it on Multisim with two IRFR024N and a 5V pulsed input but it didn't work. The output for the gate signal of the low side MOSFET remains at the -VCC while the output for the gate signal of the high side MOSFET remains at the zero.

 

[barry]

Show your schematic. What is “zero ground”? Do you mean “ground”.

if you connect VCC to -12 and COM to -24, your logic input is now referenced to -24V, not zero. And VCC will be -12 V referenced to ground, not +12v.

 

[KlausST]

I wonder if it's possible..

..the answer is given in the datasheet...

"ground" is just a name ... for a signal that usually acts as reference to (all) voltages.

Note: when you connect two 9V batteries in series there are 3 nodes. You are free ... which one you name "Ground"

Klaus

 

[Amr Wael]

I am sorry for the late reply , thank you very much for your responses , Here is the schematic that's not working versus the second one that's actually working with +12V and GND.

 

[KlausST]

Hi,

I see.

You try to shift all the power_side_reference to -24V.

The optocoupler's supply is -19V abs. ...thus it sees +5V...so far so good.
The IR2104 ..identical with -12V ... thus it sees +12V...should work.
And also with the rest I see nothing that really is wrong. (On a quick view)

The real circuit may work.
Maybe the simulation does not work because it expects GND at COM.

Some remarks:
* all "-24V" should come from one single source and should be hard connected, otherwise you risk damage on non_synchronous power sequencing.
* most electronics designers will call your "-24V node" --> "PWR_GND" .... since it's just a name.


Klaus