want_to_see
Newbie level 6
hello all,
Im having problem with a half bridge.
The sides seem to be fighting which is generating heat.
The isolated section of circuit causing the problems is a mosfet driver (IDD614) and matched N and P mosfet array (FMP26)
It is being driven from a function generator with 5V peak to peak square wave centered at 2.5V.
![Untitled.png Untitled.png](https://www.edaboard.com/data/attachments/18/18736-25b5e39cd757f4026d2e17ba49069581.jpg)
The circuit has been built many times over and I keep having the same problems.
Ive even gone as far as to make a PCB which has teh same problems.
Throughtout the next few images, the same color convention is used where:
yellow: output (pin3 fmp26), blue: p channel gate ( fmp pin 5), pink: n channel gate (fmp pin 1), green: fnction generator input (idd pin 4).
This is the waveform when the circuit is switching 12V
![12V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg 12V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg](https://www.edaboard.com/data/attachments/18/18739-b0bb9d3b4824150aa91317016d2e447a.jpg)
Switching 60V
![60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg 60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg](https://www.edaboard.com/data/attachments/18/18740-e37c01bd0c691b1317cbb6fee650b378.jpg)
this is the output with just the function generator on and power supply swtiched off
is it a loading issue? I just dont understand this.
![no_power_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg no_power_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg](https://www.edaboard.com/data/attachments/18/18741-0c200ded21107169fd03c6fc3462fe19.jpg)
As the rate of switching speed is increated, the "fighting" takes up a larger percentage of the waveform.
![1.1MHZ_60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg 1.1MHZ_60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg](https://www.edaboard.com/data/attachments/18/18738-d60a4f17dcbc700bc9279c5a0d1c40cb.jpg)
When a the load (1nf capacitor) is connected at teh frequency i want to run at, 1.2Mhz,, the loading becomes worse
![under1nfload__1.2MHZ_60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1 - Copy.jpg under1nfload__1.2MHZ_60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1 - Copy.jpg](https://www.edaboard.com/data/attachments/18/18742-92f246b8ab0c26a6f6e1bd01704684b3.jpg)
When I was searching for a solution to this, I came upon this post when i why i registered.
Its somewhat similar but the load here is capacative not inductive.
I realy appreciate any help i can get on this.
https://www.edaboard.com/threads/241410/
Im having problem with a half bridge.
The sides seem to be fighting which is generating heat.
The isolated section of circuit causing the problems is a mosfet driver (IDD614) and matched N and P mosfet array (FMP26)
It is being driven from a function generator with 5V peak to peak square wave centered at 2.5V.
![Untitled.png Untitled.png](https://www.edaboard.com/data/attachments/18/18736-25b5e39cd757f4026d2e17ba49069581.jpg)
The circuit has been built many times over and I keep having the same problems.
Ive even gone as far as to make a PCB which has teh same problems.
Throughtout the next few images, the same color convention is used where:
yellow: output (pin3 fmp26), blue: p channel gate ( fmp pin 5), pink: n channel gate (fmp pin 1), green: fnction generator input (idd pin 4).
This is the waveform when the circuit is switching 12V
![12V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg 12V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg](https://www.edaboard.com/data/attachments/18/18739-b0bb9d3b4824150aa91317016d2e447a.jpg)
Switching 60V
![60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg 60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg](https://www.edaboard.com/data/attachments/18/18740-e37c01bd0c691b1317cbb6fee650b378.jpg)
this is the output with just the function generator on and power supply swtiched off
is it a loading issue? I just dont understand this.
![no_power_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg no_power_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg](https://www.edaboard.com/data/attachments/18/18741-0c200ded21107169fd03c6fc3462fe19.jpg)
As the rate of switching speed is increated, the "fighting" takes up a larger percentage of the waveform.
![1.1MHZ_60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg 1.1MHZ_60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1.jpg](https://www.edaboard.com/data/attachments/18/18738-d60a4f17dcbc700bc9279c5a0d1c40cb.jpg)
When a the load (1nf capacitor) is connected at teh frequency i want to run at, 1.2Mhz,, the loading becomes worse
![under1nfload__1.2MHZ_60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1 - Copy.jpg under1nfload__1.2MHZ_60V_yellowoutput-bluepin5-greenfunctiongen-pinkpin1 - Copy.jpg](https://www.edaboard.com/data/attachments/18/18742-92f246b8ab0c26a6f6e1bd01704684b3.jpg)
When I was searching for a solution to this, I came upon this post when i why i registered.
Its somewhat similar but the load here is capacative not inductive.
I realy appreciate any help i can get on this.
https://www.edaboard.com/threads/241410/