Dealing with IR2108 MOSFET/IGBT Driver

• Dealing with IR2108 MOSFET/IGBT Driver
  Posted by hussamaldean on 25 May, 2018 08:56
• Hi all
  recently I bought this MOSFET driver which I will use to build an inverter (single and three phase).
  However, when I tried to use on of them to control the 2 mosfets I have for single phase inverter, I can see only the positive wave not the negative (i.e half-wave rectifier) based on the circuit below
  
  
  
  capacitor 10uF 400V
  resistors 100Ohm
  diode 0.5V forward voltage drop
  
  any solution or one mosfet driver drives only 1 mosfet ?
  
  regards
  
• #1 Reply
  Posted by Seekonk on 25 May, 2018 13:10
• I know that circuit is right off the data sheet, IT IS CRAP AND WILL NEVER WORK.  It is a test schematic for testing each output SEPARATELY.  Tie the two outputs together!
• #2 Reply
  Posted by hussamaldean on 25 May, 2018 14:21
• Quote from: Seekonk on 25 May, 2018 13:10

  I know that circuit is right off the data sheet, IT IS CRAP AND WILL NEVER WORK.  It is a test schematic for testing each output SEPARATELY.  Tie the two outputs together!
  

  any suggestions?
• #3 Reply
  Posted by jdraughn on 25 May, 2018 14:46
• Each of those drivers will drive two mosfets, but the output on the schematic can be misleading because it looks like two outputs for connecting each side of a load when they should be tied together.  The top mosfet is responsible for passing the input voltage out, and the bottom one is responsible for passing the voltage coming in from the right, down to ground. You need two sets of the above circuit (which is a half bridge), one for each side of the load to create a full h-bridge.
• #4 Reply
  Posted by Doctorandus_P on 26 May, 2018 19:19
• If you want more sensible feedback, then post the complete schematic of what you have tried, and tell us what kind of signals you have measured, and what you want etc.
  
  A cut & paste of an incomplete picture from a datasheet does not tell us much.
• #5 Reply
  Posted by hussamaldean on 26 May, 2018 19:24
• Quote from: Doctorandus_P on 26 May, 2018 19:19

  If you want more sensible feedback, then post the complete schematic of what you have tried, and tell us what kind of signals you have measured, and what you want etc.
  
  A cut & paste of an incomplete picture from a datasheet does not tell us much.
  

  Hi
  I used the same circuit from data sheet and I applied PWM signal on HIN & LIN where HIN is PWM for like 10ms and pulled LOW while LIN is HIGH then HIN is LOW and LIN is PWM for 10ms
   
• #6 Reply
  Posted by Seekonk on 27 May, 2018 06:40
• I don't understand. Did you tie HIN and LIN together?
• #7 Reply
  Posted by hussamaldean on 27 May, 2018 06:41
• Quote from: Seekonk on 27 May, 2018 06:40

  I don't understand. Did you tie HIN and LIN together?
  

  no
  each one is connected to different pin of arduino
• #8 Reply
  Posted by Seekonk on 28 May, 2018 12:45
• I see no reason why you would use two pins on three phase. 
• #9 Reply
  Posted by james_s on 28 May, 2018 22:33
• Keep in mind that LIN is inverted and HIN is not, so if you tie both together and drive with the same signal then the output will toggle between the two MOSFETs, which is what you want to happen.