I am planning a bidirectional motor driver using the AOP605 IC (two complementary P/N channel MOSFETs). I will drive a motor drawing about 300 mA (1.5A when stalled). I will use current sensing to sense the endpoint of the mechanical system (stall of the motor).
The system will be controlled by an Attiny85 (or by an ATMega328 for two channel application).
The first step of this project has been realised using two relays per channel instead of the MOSFETs. In this second step I am planning to replace the relays with MOSFETs.
Simplicity is my No:1 priority. There will be no PWM. The motor will be driven directly until it stalls. So the gate capacitance etc. is not a problem in this setting.
This is the schematic of the H Bridge:
I have omitted the flyback diodes for clarity. They are already integrated in the AOP605.
As the datasheet of the AOP605 states, the ON resistance of the P channel MOSFET at a VGS of -4.5V is less than 58 mohm. The ON resistance of the N channel MOSFET at a VGS of 4.5V is less than 43 mohm. This data suggests that these MOSFETs can be used as "logic level MOSFETs" as the working current is relatively low. As the MOSFET side will have a higher supply voltage (about 9 V) the high side P channel MOSFET will have a VGS of more than -4.5V (actually about minus 8 - 8.5 V). So I think the H Bridge should work without any problems.
My question is about the driving circuit. Can I omit the two 2N2222 transistors and drive the gates directly from the microcontroller (maybe using a series resistor)?
In this case I will also omit the two 10k resistors connected to the collectors of the transistors.
Theoretically, 5V for the N channel MOSFET is enough to turn it on with an RDSon of 43 mohm. 0 V from the microcontroller output will lead to a VGS of -9V for the P channel MOSFET and this will turn it ON adequately.
Am I right?
Thank you very much in advance...
The system will be controlled by an Attiny85 (or by an ATMega328 for two channel application).
The first step of this project has been realised using two relays per channel instead of the MOSFETs. In this second step I am planning to replace the relays with MOSFETs.
Simplicity is my No:1 priority. There will be no PWM. The motor will be driven directly until it stalls. So the gate capacitance etc. is not a problem in this setting.
This is the schematic of the H Bridge:
I have omitted the flyback diodes for clarity. They are already integrated in the AOP605.
As the datasheet of the AOP605 states, the ON resistance of the P channel MOSFET at a VGS of -4.5V is less than 58 mohm. The ON resistance of the N channel MOSFET at a VGS of 4.5V is less than 43 mohm. This data suggests that these MOSFETs can be used as "logic level MOSFETs" as the working current is relatively low. As the MOSFET side will have a higher supply voltage (about 9 V) the high side P channel MOSFET will have a VGS of more than -4.5V (actually about minus 8 - 8.5 V). So I think the H Bridge should work without any problems.
My question is about the driving circuit. Can I omit the two 2N2222 transistors and drive the gates directly from the microcontroller (maybe using a series resistor)?
In this case I will also omit the two 10k resistors connected to the collectors of the transistors.
Theoretically, 5V for the N channel MOSFET is enough to turn it on with an RDSon of 43 mohm. 0 V from the microcontroller output will lead to a VGS of -9V for the P channel MOSFET and this will turn it ON adequately.
Am I right?
Thank you very much in advance...
