New lower price for Axon II ($78) and Axon Mote ($58).
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Actually, I don't think I will need the second transistor, since my microcontroller (STM32) allows the output pin to be configured as open-drain.I can just add a pull-up to supply voltage.
Voltage on any Pin except RESETwith respect to Ground ................................-0.5V to VCC+0.5VVoltage on RESET with respect to Ground......-0.5V to +13.0V
You should however not rely on MOSFETs with only 3.3V to spare - go BjT.
am i reading you correctly that you would recommend using a BJT transistor instead of a MOSFET when your trigger voltage is 3.3V? or are you suggesting using the transistor to trigger the MOSFET?
it was my understanding many logic level MOSFETs had driver circuitry built in to buffer a (lazy) designer from these issues.
You're better off driving a MOSFET gate ON hard (i.e. not with a pull up/down).You should however not rely on MOSFETs with only 3.3V to spare - go BjT.Even better... Up the voltage. 10A @ 3.3V is gonna get you in trouble, as every little resistance in wires and contacts will seem huge.
are you sure?most microcontrollers maximum voltage on an input pin very close to VCC.check the electrical specification for IO pins in the datasheet.
the power draw of your microcontroller will be very low compared to your motors.have you considered just using a 5V microcontroller?
Sorry I didn't make it clear. The supply voltage is 7.4V (2 cells lithium polymer). Only the microcontroller, sensors, and radio run at 3.3V.
What's the purpose of D2? And isn't it intrinsic in Q3? Same for D4.
I'm assuming the 2 stage driver is to make switching faster?
If I only do, say, 25kHz (to clear the audible range), does it really matter?
What's the purpose of R5 and R10? Can't they be shorted? Why only pull them 1/3 way?
If D2 dies, it shunts and saves the life of the more expensive MOSFET. But do use a power Schottky or a similarly fast diode.
No, it's to get the right polarity, keeping the 3.3V side 3.3V.
Current limit and protection against oscillations.