SBAS667F April 2016 – April 2020 AMC1301
The AMC1301 incorporates front-end circuitry that contains a fully-differential amplifier followed by a ΔΣ modulator sampling stage. The gain of the differential amplifier is set by internal precision resistors to a factor of 4 with a differential input impedance of 22 kΩ. Consider the input impedance of the AMC1301 in designs with high-impedance signal sources that may cause degradation of gain and offset specifications. The importance of this effect, however, depends on the desired system performance.
Additionally, the input bias current caused by the internal common-mode voltage at the output of the differential amplifier causes an offset that is dependent on the actual amplitude of the input signal. See theIsolated Voltage Sensingsection for more details on reducing this effect.
There are two restrictions on the analog input signals (VINP and VINN). First, if the input voltage exceeds the range GND1 – 6 V to VDD1 + 0.5 V, then the input current must be limited to 10 mA because the device input electrostatic discharge (ESD) protection turns on. In addition, the linearity and noise performance of the device are ensured only when the analog input voltage remains within the specified linear full-scale range (FSR) and within the specified common-mode input voltage range.