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I finally got that 18F4550/HIP4082 board working

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Speakerguy

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Two weeks ago or so I posted about some problems I was having with the HIP4082. It was a 'well duh' type problem as someone eventually pointed out. In trying to fix it, I had components blow up on me even though the HIP was supposed to have shoot-through protection. I'm not 100% sure it was shoot through though. One low side FET and the two diodes for it (one Schottky, one TVS zener) were all blown. Could have been overvoltage, but they all were rated to 40V and the TVS clamps at 27V. I had the drive signals to the HIP4082 high side FET's both set permanently 'high' and was modulating the low side FETs. This is shown in the HIP schematic as the typical full bridge implementation b/c the HIP is supposed to prevent shoot through regardless of the high side inputs being 'high' all the time. In my case, however, stuff definitely blew up.

ANYWAY, I finally got it going by running the PIC 18F4550 Enhanced CCP module in half bridge mode and cutting traces / jumpering the two drive signals as appropriate to the four control pins on the HIP4082. Works like a charm! My 12V 5A gearmotor is successfully running off my 24V supply in full bridge mode. The all-SMT power board (DPAK mosfets and SMC diodes) get slightly warm at full speed but that's it.

I'll take pics later, but I'm glad it's finally working.

ETA: For the record, a 12V/5A gearmotor that turns at 60RPM has a LOT of torque.
 
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Curious minds want to know what sort of dead time did you come up with on the half-bridges? Any link to the motors, surplus store?
 

Speakerguy

Active Member
About 0.5us. I have deadtime set to zero with the PIC, so it is entirely set by the dead time setting resistor on the HIP4082 (current value is 10K which is near the minimum).

The motor is just something I found on eBay. I don't know if it's price competitive or not.

Reversible Electric Gear Motor 12v 50 RPM Gearmotor DC - eBay (item 220402477864 end time May-24-09 10:46:27 PDT)

Edited to Add: I just scoped it, looks like the dead time with a 10K resistor on the HIP4082 is 0.6us exactly. This matches what the data sheet says for running the chip from a Vdd of 12V. Interestingly enough, when the system is running it screws up my wireless keyboard, but not my wireless mouse??? Gotta be some EMI going on there.
 
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Edited to Add: I just scoped it, looks like the dead time with a 10K resistor on the HIP4082 is 0.6us exactly. This matches what the data sheet says for running the chip from a Vdd of 12V.
Appreciate you checking, will use for future reference on the half bridge of PIC, and FET drivers. Pretty beefy looking motors.... nothing's going to slow those down.
 

rlwoodjr

New Member
Circuit diagram

Do you have a schematic for the working HIP4082? I have ordered some and was looking for an example that worked.
 
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