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Old Oct 12, 2012, 06:14 AM
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DIY low voltage BLDC controller?

I have been designing simple half-bridge boards that I could combine to create a variety of different motor drivers. Two of them would let me create a brushed motor driver with reverse, 3 of them could drive a brushless motor, and 4 of them could drive a bipolar stepper motor.

I was planning on using the IR2101 driver, but then I realized that they require at least 10v, so anything under a 3s battery would not work. The IR2301 will work with 5v, which would allow me to run 2s batteries, but I don't see anything for running a single lipo (3.7v), and the IR2301 cost quite a bit more then the IR2101. Digikey has the IR2101 drivers for only 1.14 each in quantites of 10, which is a great price.

Is a p-channel mosfet for the high side about the only option I have and just driving them directly from a microcontroller? I have had poor experiences with using p-channel mosfets, they always get so hot so quick, but maybe I just haven't been spending enough money on them, buying ones with a higher RDS then I could be.

So, what I guess I am asking is, does anyone know of a driver that will drive high sided n-channel mosfets with a single lipo, or is a p and n channel combo my best bet?
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Old Oct 12, 2012, 07:09 AM
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I just came across this article about using a 555 timer to generate the voltage needed for the high side n-channel fet: http://www.ti.com/lit/an/slva444/slva444.pdf

In this article they use it so you can have 100% duty cycle. I am going to try and build a discrete totem pole driver so I can supply my own gate voltage. I will breadboard it and see if it looks like it will work alright. If so I won't even bother with a dedicated driver IC, I will just build my own using a PWM output from my microcontroller to run the charge pump and use totem pole drivers.
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Old Oct 13, 2012, 09:05 PM
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Chargepump would probably be cheaper and require minimal external components - one IC, 3/4 caps.
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