IR2153 shoot-through - Page 1
Forum section: electronics / projects

author: throbscottle
author_rank: Contributor
timestamp: March 14, 2024, 11:23:35 pm
content: I found a simple variable duty PWM motor speed controller on YouTube using the IR2153 (you split Rt and put a diode in each leg to get the variable duty). I actually have IR21531S. The transistors I'm using are FDP047AN08A0 because I had them in my junk box, and I thought if I go for the low Rds(on) I can get away without heatsinks. They are way over-powered since the motor will draw 5A max at 24V. But I had the impression the chip would drive them adequately.So first I built it on SBB. My board-pull components have short leads and I kept the frequency down in the low KHz range (Rt 10k, Ct 100n) so I didn't think that would be an issue. After getting patchy functionality and melting a couple of holes in the SBB I switched to perf-board. Everything very tight and short on this, though I've since learned I may need to change the ground path. Still overheating. At some point the low side mosfet and high side driver failed pin 6-8 short and G-S short on the tranny. Replaced chip and mosfet. After testing current at 24V I found my experimenting motor (smaller than the proper one), even at 50% duty was drawing ~600mA but current drawn from the supply was ~2.2A, which appears to be massive shoot-through.The circuit won't work at all with gate resistors much lower than 1k. It has a 1n4001 for the boost diode and a 4.7uF electrolytic for the boost cap. The supply resistor to Vcc is 1k5, with 100n decoupling cap. There is a 330uF across the incoming supply.

author: Andy Chee
author_rank: Super Contributor
timestamp: March 15, 2024, 03:57:29 am
content: According to the datasheet, the IR2153 has a fixed deadtime of 1.2usThe most likely cause is that your gate drive is ringing/oscillating due to stray inductance/capacitance.Post a picture of your schematic.

author: CaptDon
author_rank: Super Contributor
timestamp: March 15, 2024, 01:24:45 pm
content: You must have all kinds of ringing and other gremlins running around. A lower value gate resistor should be better not worse because it would pull the gate charge out quicker which in your case increased ringing and gremlins. When you are switching inductive loads you need LOTS of ground plane and decoupling and probably some snubber circuits also.

author: throbscottle
author_rank: Contributor
timestamp: March 15, 2024, 07:39:58 pm
content: Hmmmm...I just tried an experiment before posting. First connected motor 0v to the source terminal of the low transistor. Didn't make any difference, or at least, none that I could notice. Motorwill run for a second or two at power on, then stops. Power cycling produces repeat runs. So I guess the chip is shutting down due to overload? (so glad I inserted a dead-man's switch!)I also tried connecting a small halogen bulb in place of the motor. Didn't light. After this, motor didn't run. No power to top transistor drain. Inspection showed the 0.5mm wire connecting the drain to the power had fused! WTF? I think maybe an earlier bulb-test could be what blew the first chip and tranny.The chip is the IR21531 - so it has the 0.6uS dead-time. Didn't realise until after I got it.Here we go anyway, 3 photos and a schematic:The JIS connector is for power. The two prongs sticking out are to clip croc leads onto for the motor. The 0R22 is for current sensing. It's part of a larger circuit, this is just to test this particular setup. My original tests were using a 12v supply. so the current was less drastic! The big preset ended up at about 1k2, so I've put that in the drawing as a plain resistor.The chip 0v and source of the lower transistor are in a star connection to the JIS connector. The bulk cap is just kind of hanging off somewhere but I didn't think this would be a problem.Here's a link to the video. Schematic at 3.00. I only just noticed those 10k resistors from the transistor gates to 0v. Surely it should still work without those?

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 15, 2024, 08:13:53 pm
content: Well it will certainly never work according to your schematic!!Why did you change it from the original and why are you using substitute components that are different in function to the original ?Your first problem is R7/C8 I see where your coming from but you need much more decoupling to supply the mosfet driver, try 10uF at least and push the zener current nearer its limit of 25mA an average of 5mA is unlikely to meet drive requirements.2nd problem is D4/C24 completely unsuitableAnd finally R9 & R11, how do you expect mosfets to switch with no drive.Try following the original circuit.

author: Andy Watson
author_rank: Super Contributor
timestamp: March 15, 2024, 08:18:48 pm
content: Quote from: throbscottle on March 14, 2024, 11:23:35 pmThe input capacitance of your mosfets is given in nF - that together with the 1k gate resistors will give a time constant alone that will soak-up the dead-time provided by the IR2153. I would suggest lowering the gate resistor value by at least an order of magnitude.If you do that, the mosfets should switch much quicker - which means that the boost capacitor will charge much quicker - probably pulling Vcc low enough to trip the under-voltage detection. I think you need to add some micro-farads across C8 - at least several times the value of the boost capacitor.QuoteThey're not the fastest!

author: throbscottle
author_rank: Contributor
timestamp: March 15, 2024, 09:52:59 pm
content: Well, I got it working!For those who didn't properly read my original post, the circuit wouldn't work at all with gate resistors much under 1k. At least with R9 and R11 as 1K I got something!First off I changed the 1N4007 for a pretty purple one I dismantled from something. I'm pretty sure it's an ultrafast rectifier. It was in my "unidentifiable" pile.Then I changed the path of the 0v connection so the V- lead of the bulk cap goes directly to the chip, and I changed that cap from 330uF to 220uF, but at least this one is rated at 50v and not 16v - which was never going to last long on a 24v supply!I connected the chip 0v to the lower transistor source. Added 1000uF bulk cap across the JST connector since I found the PSU voltage was getting chopped up badly when the circuit ran. Drain of top transistor now blew the thin connecting wire even worse, so I replaced that wire with a NTC inrush limiter. Moved the transistors further apart.So now I need to figure out which of my changes was the magic sauce, and try a higher frequency. At least I can remove the pesky dead-man's switch!Ran without any overheating - trannys at a nice 20 degrees C. Have now been able to reduce the gate resistors down to 22R.Anyway, I will take your advice and connect some uF across C8. R7 is per datasheet recommendation - I suppose I can tinker with it.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: March 15, 2024, 10:11:21 pm
content: I have a dumb question. What is the purpose of Q6? It looks like it just shorts out the motor winding. Is this to allow regen current flow while Q5 is off?

author: Andy Watson
author_rank: Super Contributor
timestamp: March 15, 2024, 10:39:53 pm
content: Quote from: Ground_Loop on March 15, 2024, 10:11:21 pmIt does. It's body diode also prevents negative excursions of the terminal - which is also connected to the IR2153. Also, the operation of the IR2153 is dependant on the boost-capacitor being regularly charged - which is ensured by Q6.

author: throbscottle
author_rank: Contributor
timestamp: March 15, 2024, 11:54:33 pm
content: It shorts out the back EMF of the motor so the current can keep flowing instead of hitting a wall and creating a voltage spike. A diode will do the job of Q6 (well, obviously not the charge pump part), but with a transistor you eliminate the Vf. Not important for small motors but apparently it can make a big difference with large ones. My case is marginal, but as soon as I found there is a sefl-oscillating mosfet driver, I had to use it for my project!