dc-dc push pull topology with low side MOSFETS

[Kryptone]

Hello Members,
I am building a dc-dc converter using push pull topology with the SG3525 but I get Vgs=0V for Q1 and Vgs= 0.8V for Q2 however I need to get Vgs>=8V to fully turn on the FETs. I even used the IR2110 in between the SG3525 and the FETs which are low side. Where did I go wrong? and how can I get Vgs>=8V????

Please help!!!!!!!!
See schematic below however I used the IR2110 mosfet driver.

 

[FvM]

See schematic below however I used the IR2110 mosfet driver.

Sounds confused. SG3525 can drive MOSFETs directly. If you need higher gate current than +/- 0,4 A, you'll use high current gate drivers or a NPN+PNP transistor buffer.

 

[--BawA--]

I am building a dc-dc converter using push pull topology with the SG3525 but I get Vgs=0V for Q1 and Vgs= 0.8V for Q2 however I need to get Vgs>=8V to fully turn on the FETs. I even used the IR2110 in between the SG3525 and the FETs which are low side. Where did I go wrong? and how can I get Vgs>=8V????

I have already concluded my thoughts on your another thread https://www.edaboard.com/threads/312765/
and don't see any reason why you are using ir2110.

 

[D.A.(Tony)Stewart]

If you don't get near 0V drop on the FETS when they are ON, then they or the gate voltage are the problem.

If you do get near 0V drop and the output is low under load, then your transformer is the problem.

If the 12V dips under load then that is the problem.

Change the switcher frequency to see how it affects the above results to ensure it is tuned to your transformer inductance to avoid saturation yet have sufficient time to energize the core.

 

[Kryptone]

If you don't get near 0V drop on the FETS when they are ON, then they or the gate voltage are the problem.

If you do get near 0V drop and the output is low under load, then your transformer is the problem.

If the 12V dips under load then that is the problem.

Change the switcher frequency to see how it affects the above results to ensure it is tuned to your transformer inductance to avoid saturation yet have sufficient time to energize the core.

WHen I set the voltage from the power supply using the pot to about 14V or 15V and connect it to the dc-dc converter the voltage drops to about 12.5V What could be the problem? it use to occur when the transformer is in and but now it even occurs when I take out the transformer......

Please help!!!!!

 

[ALERTLINKS]

Some component is drawing extra current, for example a faulty IC.

 

[Kryptone]

Some component is drawing extra current, for example a faulty IC.

What is the voltage that I should get from the output of the SG3525?????

 

[FvM]

What is the voltage that I should get from the output of the SG3525?

Pulses between 0 and Vcc-1, if SDN isn't activated, the oscillator is working and voltage at pin 9 (COMP) is above oscillatorramp at pin 5 (CT). The conditions are usually checked with an oscilloscope.