I'm interested in Buwizz PCB and components. Can someone share good photos of the Buwizz PCB (both sides)? It will be very cool to see Buwizz 2.0 but older versions will also be good.
I don't have this part, so I can't directly give you the photos that you are looking for, but there is at least one teardown video floating around that we can use to see what is inside the BuWizz 2.0 module.
The module contains 2x 850mAh LiPo batteries:
The top of the PCB looks something like this:
I wasn't able to find an image showing the back of the PCB
System on a chip
From the above images, we can see that the main microprocessor is a Cypress PSoC 4200 series. Looking at the datasheet, we see that is a BLE-enabled system on a chip running at 48MHz with 128KiB of flash.
There are at least 4 DRV8833 chips present on the PCB. This chip is a dual H-bridge. The datasheet for the part indicates that each channel can handle 1.5A RMS/DC or 2A peak. The specs for the BuWizz indicate:
- Max continuous current per channel: 4 A
- Max instantaneous current per channel: 6.5 A
- Max continuous power per channel: 36 W (HIGH speed mode)
- Max instantaneous power per channel: 55 W (HIGH speed mode)
- Max total power: 45 W
- SLOW: 5.2 V
- NORMAL: 7.2 V
- FAST: 9.2 V
- LUDICROUS: 11.2 V
I'm not sure how 4A per channel is achieved safely using the DRV8833. Given that 4 dual H-bridges are included, it is safe to assume that each chip is driving each output using both H-bridges in parallel, but according the the datasheet, this still only gets us to 3A RMS/DC per channel.
My hunch is that they are simply driving these parts harder than intended. We can see that they are using them at 11.2 volts, while the datasheet recommends a max operating voltage of 10.8 volts. It's worth noting that the max quoted continuous power per channel (36W) is very close to what you would get from a parallel configuration running at 11.2V (11.2V * 3A = 33.6W).
The BuWizz has carved out a niche for itself by going well beyond recommend operating power (the LEGO PF battery box tops out at 9V * .8A = 7.2W or less than a quarter of the BuWizz), so I wouldn't be surprised if they are running the motor drivers a bit hot.