Hello Folks
The L6470 datasheet (see snapshots provided by Jacek) clearly says that Vreg should be connected to VDD, as they are not connected internally. Further, VDD should have 10uF Cap to work properly.
Surprisingly, the X-NUCLEO-IHM02A1, which has two of these chip in daisy-chain mode, never connects VDD with Vreg, and there is no 10uF Cap on VDD, and VDD is connected via external power supply. Not at all aligned with datasheet. However, datasheet further says that Vdd and Vreg can be tied all together with external power supply. I have yet to see a schematic by ST where that has been implemented.
On another side, EVAL6470PD schematic also connects Vreg and Vdd of one single L6470PD. That seems to be one of the method prescribed by datasheet. However, it's not mentioned or clarified that can we have both Vdd and Vreg connects to external 3.3V power supply?
My application requires daisy chaining of four L6470PD devices.
Now, my Question is if I have multiple L6470PDs then may I still connect VDD with Vreg? May I have all the Vdds and Vregs of all the L6470 CHIPs tied together and then connect them with external 3.3V supply? Is that fine? or shall I strictly follow the schematic X-NUCLEO-IHM02A1 for multiple L6470?
I have designed a PCB by following design suggestions provided by datasheet. However, it never works properly. The driver behaves erratically as it has mind of its own.
The datasheet is not at all aligned with schematic attached of X-NUCLEO-IHM02A1. I am bamboozled right now. A serious help is required!!
FYI, please see the attached schematic of X-NUCLEO-IHM02A1 and my attached schematic snapshot below for your reference:
