IHM01A1 L6474 reset pin during active output

zubairzulkifli · ‎2015-10-13

Posted on October 13, 2015 at 11:11

I have some question regarding the board (maybe anyone of you have a better understanding on electronic). I use the board with stepper motor to moves a cart on the linear drives. The move will be limited by proximity sensor that activates the interrupt on my board. (I use Arduino board). I use 45V with 3A for my stepper motor. Everything was okay with the coding. But as I try to improve the code for my application, I'd accidentally mess up the board, The situation was like this:

1.During setup, the L6474 library will be activated. And the motor will be rotates towards the proximity sensor.

2. Normally after reaching the sensor, interrupt will be activated and then the HardStop() function will be followed. (This code was ok.)

3. But as I play with the code, after the interrupt activates, I use the Reset() function instead of the HardStop() function. (Silly but dummy mistake). After that it didn't function anymore. I immediately check the L6474 datasheet. It states that it is not recommended to reset the device when outputs are active. On the power supply display, it didn't show 45V anymore but instead about 1,0 V.

4. The question is, did you think the chip is damaged? Normally if the chip are damaged, it would smell like a smoke or it burns, but from the appearance only, the chip looks ok for me.

Thanks in advance!

#ihm01a1 #l6474

estie · ‎2015-10-20

Posted on October 20, 2015 at 14:24

Next time, try reading the data sheet *before* using the chip.

Bulk overheating is not the only reason a chip can be damaged, so the sniff test is not a reliable diagnostic for a working device.

Cutting the device with full current flowing into an inductance will produce a voltage spike ( you may need to learn some basic electronics too ). You most likely exceeded the electrical conditions of the output transistors. Dead chip , dead board. Luckily these boards are cheap.

Enrico Poli · ‎2015-11-18

Posted on November 18, 2015 at 16:48

Hi Zulkifli,

The combination of high voltage (you are at the operating limit of the device) and high current into the motor (3 A) is very critical. As soon as you reset the IC, the power stage is disabled abruptly, this cause two main effects:

- the electric stess on the internal MOSFETs is very strong, but they are able to sustain it once in a while

- the energy ''stored'' into the motor as current reflows into the bus, charging it. The voltage in this case can rise up to exceedng the breackdown voltage of the circuitry.

If the device is actually damaged, in this case you should see a short beteen VS or VBOOT and GND.

Regards

Enrico