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circuit of precision 1A current source, how thus this circuit work?
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aidilismadi:
aidilismadi:
circuit of precision 1A. can anyone explain me about the voltage and current flow. and what is the function of op amp and mosfet at the circuit.
capt bullshot:
https://en.wikipedia.org/wiki/Current_source
Mechatrommer:

--- Quote from: aidilismadi on March 08, 2018, 10:08:02 am ---circuit of precision 1A. can anyone explain me about the voltage and current flow. and what is the function of op amp and mosfet at the circuit.

--- End quote ---
V = I x R, we use 1 ohm resistor, so for 1A to flow, there will be 1V across the resistor V = 1A x 1ohm = 1V. thats why Vref is set to 1V there. if less current flowing, there will be less than 1V across resistor, opamp output will go high to close (switch) (or turn on) the mosfet to allow more current, but when current exceeding 1A, bigger than 1V across resistor, opamp will sense this and output will go low to shutdown the mosfet. this will go on and on until power supply is removed. so opamp job is to control mosfet to make sure 1V across resistor, ie 1A current. if more current, switch off mosfet, if less current switch on mosfet. faham? ;)
ogden:

--- Quote from: Mechatrommer on March 08, 2018, 11:58:36 am ---
--- Quote from: aidilismadi on March 08, 2018, 10:08:02 am ---circuit of precision 1A. can anyone explain me about the voltage and current flow. and what is the function of op amp and mosfet at the circuit.

--- End quote ---
V = I x R, we use 1 ohm resistor, so for 1A to flow, there will be 1V across the resistor V = 1A x 1ohm = 1V. thats why Vref is set to 1V there. if less current flowing, there will be less than 1V across resistor, opamp output will go high to close (switch) (or turn on) the mosfet to allow more current, but when current exceeding 1A, bigger than 1V across resistor, opamp will sense this and output will go low to shutdown the mosfet. this will go on and on until power supply is removed. so opamp job is to control mosfet to make sure 1V across resistor, ie 1A current. if more current, switch off mosfet, if less current switch on mosfet. faham? ;)

--- End quote ---

Right. In addition to that you have to understand how opamps work.
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