Custom FOC shield design: 6PWM or 3PWM with no EN?

Hi everyone.
I have tried the new Simple FOC shield with current sensor. But the pcb layout and the power limit are not satisfied me. So I’m working for my own FOC shield capable of 24V 5-10A within several bucks.
The design is based on FD6288, a cheap gate driver using in lots of BLDC ESCs.The problem is that it has no EN pin. I wonder if its impotant for most applications.
If the answer is yes then I will make it works at 6 PWM that allows the motor free running.
If the answer is no then 3 PWM is enough and the shield will be stackable for 2 motors.
The preview of schematic is below.
Any suggestion is welcomed.

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It is always good to see new designs. Have you seen Antun’s new powershield?

I don’t think it is quite for sale yet - but it has been tested.

I tried to look at fd6288 datasheet but can’t read chinese. I don’t think the lack of ENABLE will cause problems. Do you know for certain you can use 3PWM in the way you show in schematic i.e. connectint HIN/LIN to same pin?

yes, I have seen it.
BTN8982 is so powerful that its quite expensive and a bit overkill.

Read the datasheet again and found that connectint HIN/LIN together is not allowed…
LIN is NOT conversed. I am comfused it with some other chip. So sad and have to replaced it.

Good news!
Theres a chip which is pin-to-pin compatible.
the only different is LIN is conversed.
US$0.35 with +1.2A/-1.4A drive ability and build in 100ns deadtime
But still, Chinese datasheet.

I would consider providing a way to enable/disable the driver. I made my first board without this function, and I regretted it. For practical use, you want both a way to save power (for longer battery life!), and protect the motor from overheating.

Here is the datasheet in english, @Owen_Williams :

Are you sure it supports the mode in which you’re wiring it, just using 3-PWM? It isn’t mentioned in the datasheet…

You might want to consider gate resistors on the mosfets.
I assume there is more power supply circuitry on another schematic? If not, I think you want some bulk capacitance somewhere to support VBUS.

I think this looks like a very nice design, you’re doing inline current sensing, is that right?

The schematic is unfinished. Well, FD6822 doesn’t support 3PWM, so i replaced it with EG2133.

Theres no free running state (turn off all the MOS, and I wonder if it’s the correct name) but only brake state (turn on all the low side MOS) in 3PWM mode. Both of the states does not consume a lot of electricity.

Anyway, I decide to make it work in 3PWM.
Heres some almost-done preview.

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Hey, it’s an interesting board design. I’m interested to hear your impressions.

I would just suggest you to make sure to that your current sense and your shunt have good values. In my case I’ve adapted it for ±3.3Amps on 3.3V logic (±5amps on 5V).

If you wish to measure higher currents, scale the shunt value.

Really nice! I like the way you have all the FETs together, it will make it convenient for adding a heat-sink…

The PCB is arrived and is tested. So far so good except a mark mistake. It works fine within 3Amps. Larger current haven’t test yet for lacking of suitable load. While using 3.3Vref, 10mR shunt and INA240V1(20x amp), the full scale is ±8.25A.
Schematic and PCB files are uploaded for anyone interested.
In case you dont know, ABI/UVW are external interrupt for sensor, PU/PV/PW are PWM output.


Very nice and very fast, well done!