Rev1 high-side driver is for P-channel, not N-channel FETs

[WaltHolm]

Hi Rusty:

I took a peek at the design you used for the Rev1 version of the BlueESC. The driver configuration you are using seems to be for a P-channel high-side switch, yet the schematic shows a N-channel high-side switch. I can't see how you're going to get a fully-enhanced high-side transistor with this configuration, leading to poor efficiency and overheating of the high-side transistor.

-Walt Holm

[rjehangir]

Hi Walt,

Thanks so much for looking over the schematic. I really appreciate it. I'm
not an electrical engineer so I can use all the help I can get!

I actually discovered this problem myself during one of our first tests.
The FETs got so hot that they desoldered themselves. I've since replaced
the high-side with P-channel FETs on that prototype and revised the
schematic for N-channel on the high side. I added a very basic charge pump
with diode and capacitor, as you see on most N-channel ESCs. I just pushed
those changes and I'd be really grateful if you could glance at it again
and let me know what you think.

Also, what do you think about FET drivers? They are typically used for ESCs
over 30-40 amps and should improve efficiency and heating a bit. This ESC
will max out around 30 amps but it still may be a good addition. I've been
looking at IR2101 specifically.

Best,

Rusty

On Mon, Sep 1, 2014 at 11:06 PM, WaltHolm notifications@github.com wrote:

Hi Rusty:

I took a peek at the design you used for the Rev1 version of the BlueESC.
The driver configuration you are using seems to be for a P-channel
high-side switch, yet the schematic shows a N-channel high-side switch. I
can't see how you're going to get a fully-enhanced high-side transistor
with this configuration, leading to poor efficiency and overheating of the
high-side transistor.

-Walt Holm

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