Hello everyone,
objective: I am actually trying to design a curent sensor ranging from 1uA to 1A. I know it won't be possible with only one sensing resistor but my problem is to sense the 1uA.
Here are my concerns (the schematic is joined):
1) The offset voltage of the LTC6102 sense amplifier should be no more than 10uV(cf datasheet) but when i simulate with a load current of 0A, I can read an offset voltage of 20-25uV.
2) If we admitt the offset voltage is 20uV, by choosing a 100ohm sense resistor, the Current offset should be 0.2uA max. The maximum sensing voltage is given in the datasheet: 2V max which means that we can sense up to 20mA.
But, when simulating with a 1mA load current instead of having (almost) 1mA through Rin, I only have 56mA. This is due to a difference of voltage between Vsense=5.900V and Vin=5.943V which should normally be (almost) equal.
Please any help his welcome!!
regards,
charles
objective: I am actually trying to design a curent sensor ranging from 1uA to 1A. I know it won't be possible with only one sensing resistor but my problem is to sense the 1uA.
Here are my concerns (the schematic is joined):
1) The offset voltage of the LTC6102 sense amplifier should be no more than 10uV(cf datasheet) but when i simulate with a load current of 0A, I can read an offset voltage of 20-25uV.
2) If we admitt the offset voltage is 20uV, by choosing a 100ohm sense resistor, the Current offset should be 0.2uA max. The maximum sensing voltage is given in the datasheet: 2V max which means that we can sense up to 20mA.
But, when simulating with a 1mA load current instead of having (almost) 1mA through Rin, I only have 56mA. This is due to a difference of voltage between Vsense=5.900V and Vin=5.943V which should normally be (almost) equal.
Please any help his welcome!!
regards,
charles