Integrated Current Sense Amplifiers
- Kevin Li
Using a current-sense amplifier with an integrated current-sense resistor reduces the difficulty of resistor selection and PCB layout. With these devices, the connections to the current-sense resistor are optimized to achieve the best measurement accuracy and temperature stability.
Consider TI’s INA250, INA253, and INA260 integrated current-sense amplifiers. The INA250 and INA253 have analog outputs while the INA260 has a digital output current sensor which reports the current, power, and bus voltage through an I2C/System Management Bus (SMBus) interface. The figure below shows the block diagram of the INA250 along with the resistor connections.
These devices have external sense connections that enables filtering of the shunt voltage or direct connections to the current-sense amplifier. In these devices, the connections to the shunt resistor are fixed internally. The gain of the amplifier is optimized for each resistor so that the total system gain error is comparable to using a <0.1% current-sense resistor. The integrated shunt technology used in the INA250, INA253 and INA260 can support operating currents as high as 15A.