Im waiting for some humidity sensors to arrive so I can't do any more on the incubator for a while.
I want to do some work on my 12V dc motor driver. Regulars will recall the last time I asked about mosfets so it is with some trepidation that I step into the arena once again.
The state of my understanding thus far is as follows:
mosfets are superior to biploars for pwming motors.
a mosfet driver ic should be used with the mosfet
power mosfets require the v on their gate to be at least 10v higher than their source v to fully turn on.
I am using a IRF3710
http://www.datasheetcatalog.org/datasheet/irf/irf3710.pdf
in conjunction with a TC4420 driver.
http://ww1.microchip.com/downloads/en/DeviceDoc/21419c.pdf
to low side pwm a GM (R.I.P) automotive windscreen wiper motor.
I have connected the parts as per the The Power MOSFET Interfacing Circuit in the 3rd picaxe manual. That is, source to ground and drain to the low side of the motor. Correct me if this is wrong.
The gate of the mosfet is connected to the output (pin 7) of the driver ic.
I note from the data sheet that the TC4420 driver can run on a Wide Input Supply Voltage Operating Range:
- 4.5V to 18V.
Question.
Do I need to run the driver on a voltage at least 10v higher than the voltage I am seeing on the low side of motor? Or does the driver ic generate this higher voltage on its output pin by itself?
I ask because at the moment Im only seeing the same v on the output as I have on the supply. The mosfet is getting warm switching only smallish current. I thought this indicated that mosfet is not fully opening because of insufficient v on its gate and is thus generating heat because of its high resistance.
I have found this article very helpful.
http://homepages.which.net/~paul.hills/SpeedControl/MosfetBody.html
I want to do some work on my 12V dc motor driver. Regulars will recall the last time I asked about mosfets so it is with some trepidation that I step into the arena once again.
The state of my understanding thus far is as follows:
mosfets are superior to biploars for pwming motors.
a mosfet driver ic should be used with the mosfet
power mosfets require the v on their gate to be at least 10v higher than their source v to fully turn on.
I am using a IRF3710
http://www.datasheetcatalog.org/datasheet/irf/irf3710.pdf
in conjunction with a TC4420 driver.
http://ww1.microchip.com/downloads/en/DeviceDoc/21419c.pdf
to low side pwm a GM (R.I.P) automotive windscreen wiper motor.
I have connected the parts as per the The Power MOSFET Interfacing Circuit in the 3rd picaxe manual. That is, source to ground and drain to the low side of the motor. Correct me if this is wrong.
The gate of the mosfet is connected to the output (pin 7) of the driver ic.
I note from the data sheet that the TC4420 driver can run on a Wide Input Supply Voltage Operating Range:
- 4.5V to 18V.
Question.
Do I need to run the driver on a voltage at least 10v higher than the voltage I am seeing on the low side of motor? Or does the driver ic generate this higher voltage on its output pin by itself?
I ask because at the moment Im only seeing the same v on the output as I have on the supply. The mosfet is getting warm switching only smallish current. I thought this indicated that mosfet is not fully opening because of insufficient v on its gate and is thus generating heat because of its high resistance.
I have found this article very helpful.
http://homepages.which.net/~paul.hills/SpeedControl/MosfetBody.html