Timeline for Synchronous Buck High Side Driver - Why is the Fall Time of High-Side Gate Drive so Slow?
Current License: CC BY-SA 3.0
22 events
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| Jun 4, 2017 at 0:55 | history | edited | Veda Sadhak | CC BY-SA 3.0 |
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| Jun 4, 2017 at 0:46 | comment | added | Veda Sadhak | I am using the CSD19533KCS which is a 100V 86A mosfet. Also I have posted a picture with the scope measurements with reference to ground it still shows the slow fall time in the high-side gate drives. | |
| Jun 4, 2017 at 0:42 | history | edited | Veda Sadhak | CC BY-SA 3.0 |
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| Jun 3, 2017 at 10:06 | answer | added | Andy aka | timeline score: 3 | |
| Jun 3, 2017 at 3:51 | comment | added | W5VO | With 100Ω gate resistors, you're not going to see that fast of a gate transition, but I suspect that isn't the reason you're having issues. You haven't mentioned which power MOSFET you're using. That oscilloscope can't do two isolated differential measurements without additional equipment - this is a common beginner's mistake which is why exact connection points for each probe are necessary for further information. | |
| Jun 3, 2017 at 3:41 | history | edited | W5VO | CC BY-SA 3.0 |
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| Jun 3, 2017 at 3:37 | comment | added | Sredni Vashtar | So, to be clear: are you using differential probes? Otherwise, the ground clip of both probes is attached where? | |
| Jun 3, 2017 at 3:05 | comment | added | Veda Sadhak | @brhans ... You are right, my bad guys I saw the push-pull on that block diagram and assumed it was BJTs, it is actually using MOSFETs. I apologize for that mistake OlinLathrop. Note: I had to remove that block diagram because I can only upload 2 pictures. | |
| Jun 3, 2017 at 3:02 | history | edited | Veda Sadhak | CC BY-SA 3.0 |
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| Jun 3, 2017 at 2:57 | history | edited | Veda Sadhak | CC BY-SA 3.0 |
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| Jun 3, 2017 at 2:12 | comment | added | brhans | There are no BJTs in that block diagram... | |
| Jun 3, 2017 at 1:19 | comment | added | Veda Sadhak | Will upload circuit soon. | |
| Jun 3, 2017 at 1:18 | comment | added | Veda Sadhak | @OlinLathrop W5VO is right the BJT push-pull configuration I am talking about are shown in the block diagram. | |
| Jun 3, 2017 at 1:17 | comment | added | Veda Sadhak | @sstobbe The probes are connected between the gate and source of both MOSFETs directly. You are right it is swinging below -5vdc and I am not exactly sure how that is happenin, but my guess is that it has something to do with the charge pump of the driver IC. | |
| Jun 3, 2017 at 0:50 | comment | added | Sredni Vashtar | Where are the BJTs? And how did you connect your probes to the circuit? | |
| Jun 2, 2017 at 23:26 | comment | added | W5VO | @OlinLathrop I think you're confusing the block diagram of the driver IC he's using with his circuit schematic (which is not included/shown). | |
| Jun 2, 2017 at 23:01 | comment | added | WhatRoughBeast | As Andy aka says, show your circuit. Most particularly show your load. If the DRV_HI output is floating, then a high output will drive quickly to Vcc, but a low output will simply discharge the output capacitance very slowly. | |
| Jun 2, 2017 at 22:49 | answer | added | D.A.S. | timeline score: -2 | |
| Jun 2, 2017 at 22:30 | review | Close votes | |||
| Jun 4, 2017 at 6:01 | |||||
| Jun 2, 2017 at 21:46 | comment | added | Andy aka | Show your exact circuit. | |
| Jun 2, 2017 at 21:35 | comment | added | sstobbe | How are you probing both outputs? The blue trace looks like it's swinging to -5vdc when the high side driver switches | |
| Jun 2, 2017 at 21:24 | history | asked | Veda Sadhak | CC BY-SA 3.0 |