Hey everyone.
I'm working on a project in which I need to operate a 28v dc motor.
The project will be based on a pic16f series mcu.
The things i need:
1. "Over voltage protection", if the input voltage is over 29-30v - inhibit motor operation.
2. Input voltage measurement with the pic's ADC.
3. Motor current measurement with the pic's ADC.
The response time of the "Over voltage protection" isn't critical since i'm not anticipating any voltage spikes just an accidental power supply knob twist so I was thinking of using a quad op amp IC.
And to use 1 amp as a comparator for the "over voltage protection"
Another op amp as a buffer from a voltage divider to feed the ADC with low impedance voltage source.
Now the current sense is a bit tricky.
I'm expecting about 1.5A stall current and 1A operation current. I have a 0.1ohm power resistor to use for the measurement.
How can I set up a good differential amp with the two remaining op amp ?
Should i buffer the inputs ? if so I would need one more op amp. Should i switch the comparator op amp with a real comparator and use 3 op amps for the differential amp ?
I don't require too high current measurement accuracy, i will probably use only one or two digits after the decimal point (0.12A or 0.123A).
Any suggestions will be appreciated,
Mike.
I'm working on a project in which I need to operate a 28v dc motor.
The project will be based on a pic16f series mcu.
The things i need:
1. "Over voltage protection", if the input voltage is over 29-30v - inhibit motor operation.
2. Input voltage measurement with the pic's ADC.
3. Motor current measurement with the pic's ADC.
The response time of the "Over voltage protection" isn't critical since i'm not anticipating any voltage spikes just an accidental power supply knob twist so I was thinking of using a quad op amp IC.
And to use 1 amp as a comparator for the "over voltage protection"
Another op amp as a buffer from a voltage divider to feed the ADC with low impedance voltage source.
Now the current sense is a bit tricky.
I'm expecting about 1.5A stall current and 1A operation current. I have a 0.1ohm power resistor to use for the measurement.
How can I set up a good differential amp with the two remaining op amp ?
Should i buffer the inputs ? if so I would need one more op amp. Should i switch the comparator op amp with a real comparator and use 3 op amps for the differential amp ?
I don't require too high current measurement accuracy, i will probably use only one or two digits after the decimal point (0.12A or 0.123A).
Any suggestions will be appreciated,
Mike.
