Hi Engineer,
When we use the DRV11873, there are about 5 or so, and the chip is damaged. The specific situation is:
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Hi Engineer,
When we use the DRV11873, there are about 5 or so, and the chip is damaged. The specific situation is:
Hi Sanmesh,
Thanks for your attention.
The whole process only controls pwm, and the direction is fixed by hardware;
Not because of improper use of welding and production staff;
The low speed reversal is not caused by external torque, and the motor load will not change during the whole process!
In the original design, the current limiting resistor was 3.3k, but at the time there was a chip damage, thinking that the current was too large, so the current limiting resistor was replaced by 3.9k. After replacing the resistor, it is easier to reverse. However, it is not the external force or the control reversal, but the motor automatically rotates in the opposite direction, and at this time, the maximum motor speed can only reach 200 rpm!
At present, I think it should be some kind of error when starting up, such as starting current is too large, but not sure, now it will reverse for up to 10 seconds in normal use, the program will shut down the motor;
When the reversal occurs, the chip is a little hot, but it runs for several hours at 80 high temperatures, and it is not damaged (not to rule out individual differences, after all, I only tested a few, and the site only damaged a few)!
A total of one or two hundred units, two damages occurred, and the inside of the sealed case is the case that the pad is burnt out.
U2 is 11873, the heat sink pads on the pcb are burned out, and the above several vias are broken.
Questions:
1) What is the particular case that this problem happened? Is it when the motor was spinning in the correct (not reverse) direction and at 80 degrees? Is the 80 degrees celsius or fahrenheit?
Things to check:
1)Make sure V5 isnt being loaded more than 20mA. If it is loaded more than that, than maybe the FR pin is not high and is telling the device to go the wrong direction sometime. Also check the voltage of V5
2) I think getting a scope capture of one of the motor phase currents would help to see if it is abnormal and causing the device to heat up
Notes on what you have told so far are attached. Feel free to correct them if I'm wrong.