I have been looking at a series of isolation amplifiers from TI, but they are divided in 'current sensing' and 'voltage categories, when we sense current we actually sense voltage, so why do the ICs need to be categorized like that then?
Thanks.
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\$\begingroup\$ One difference is that a current sense amplifier will have a tiny shunt resistor across the inputs (so inputs nearly shorted), while a voltage sensing amplifier will usually have a very high impedance across the inputs. That will make a big difference for things like input bias currents, which have a bigger effect the larger the source impedance. \$\endgroup\$user1850479– user18504792025-03-13 12:20:24 +00:00Commented Mar 13 at 12:20
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\$\begingroup\$ That makes sense, thank you. \$\endgroup\$Bee16– Bee162025-03-19 17:50:04 +00:00Commented Mar 19 at 17:50
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A current sense amplifier will have a low value shunt resistor across the input. This shunt resistor value should be low to not cause too much voltage drop across the measured circuit.
As a result, also the shunt voltage will be small (e.g. 20mV). That's why the current sense amplifiers often have a programmable gain amplifier included (e.g. 50 V/V) , so the small "sense" voltage can be converted to a larger output voltage (e.g. 20mV * 50V/V = 1V).
Voltage sense amplifiers usually do not need to provide a high amplification of the input voltage.
In short: Current sense amplifiers can amplify very small voltages, while voltage sensing amplifiers do amplify larger voltages.
