DRV10987: drv10987

Hi Sir, sorry for the delay in reply

open-loop/align time is set to max, still, issue not solved. The issue is if I set acceleration range selection fast and set acceleration constant accordingly, the ldo of drv ic V3P3 drops, which I have connected as Vcc for my st microcontroller through which i am giving my speed PWM command. And I would also like to know the relation between speed and duty because when i am testing for some period it gives linear relation and reached a constant speed for the same incremental duty ratio. I will share my gui setting, please let me know if I am going wrong somewhere.

THANKS

Meghana

for all PWM duty the fan runs very smoothly, only the issue is with alignment, sometimes it does not start at all... for the first time switching. until a push through the hand.

 ... if acceleration is set fast, seems like draws more current and goes to current protection, and v3p3 drops

Thanks!

Meghana

hi Sir, in order to avoid the initial reverse rotation, I am enabling the ipd settings, still at some duty, the 3.3V Of DRV IC drops to 1.4 volt which resets the ST microcontroller which I am programming (duty cycle) as speed command. Actually what settings in GUI is exactly the reason for this V3P3  to drop?

Hi Sir, as per your suggestion I am now working with align and go method, now that dropping of V3P3 is not happening, it was happening only if I use IPD setting, as i have shown in image of my last post  but at each start, it goes anticlockwise and starts in the clockwise direction,...currently i have set open loop/to align time to maximum 1.6A/1.2A, and align time 0.04sec, with slow acceleration range 0.019Hz/s and 0.22Hz/s2.   

do I need to change open loop/align time ratio to the minimum value, to resolve this issue...its like in align and go it now takes some 3.36 sec to start.

Or any other setting I need to change.. currently, I disabled, initial speed detect and enable reverse drive and set to no brake......which makes my BLDC  fan  to stop slowly

Thanks

R MEGHANA

Hello Sir,

Actually in TEXAS DRV10987 EVALUAITON BOARD  dropping of Vreg 5V  is not happening, it happens in my bldc board , i have even changed the ipd current threshold value, but still i could see the dropping of Vreg if i enable IPD, (Rph-ph=2.56 ohms, Lph-ph=8.13 mH(LCR METER MEASURED ),pwm at speed pin (15khz)....I have tuned according to ipd tuning guide, these parameters are IPD BASED, not align n go, but still could not resolve.

only if i disasble IPD, Vreg doesnot drops but the performance of fan is not good at start it turns back n forth n starts....

i will share the image of my bldc hardware schem...let me know if anything we are going wrong

Thanks !

Meghana

Hi Sir, now what i have done is Vreg is isolated from the microcontroller, and i am connecting load 80mA (R load 65 ohms)  across 10uF CAPeven though (100mA is capable it should be capable to load maximum) , IN BUCK mode, motor aligns and stops.

If Vreg is isolated, if nothing is connected to this pin it works properly, so what can be the problem is it still tuning.

Thanks!

Meghana

yes Sir, 

In evaluation board, it runs proper,as in evaluation board nothing is connected to Vreg pin. and here it does not shows any OVERCURRENT FAULT

But in my hardware, i am connecting a regulator from Vreg to step down voltage to 3.3v to give to ST microcontroller, in such connection 5v at Vreg drops.

In order to verify this issue, i have isolated all my connection to Vreg, it works proper .....

but Vreg is capable to load 100mA as per datasheet, so i connected 80mA, resistor in buck mode as load, it drops still...., is it like we should not connect any load to this pin......And in standby mode vreg is resposible for vp3p and v1p8.... so again im connecting a regulator from this vreg pin externally....is this created the problem

 if there is OC fault, what parameter is reason for this,........