SBAS667F April 2016 – April 2020 AMC1301
The high-side power supply (VDD1) for the AMC1301 is derived from the power supply of the upper gate driver. Further details are provided in the Power Supply Recommendations section.
The floating ground reference (GND1) is derived from one of the ends of the shunt resistor that is connected to the negative input of the AMC1301 (VINN). If a four-pin shunt is used, the inputs of the AMC1301 are connected to the inner leads and GND1 is connected to one of the outer shunt leads.
Use Ohm's Law to calculate the voltage drop across the shunt resistor (VSHUNT) for the desired measured current: VSHUNT = I × RSHUNT.
Consider the following two restrictions to choose the proper value of the shunt resistor RSHUNT:
For best performance, use an RC filter (components R2, R3, and C3 in Figure 49) to minimize the noise of the differential output signal. Tailor the bandwidth of this RC filter to the bandwidth requirement of the system. TI recommends an NP0-type capacitor to be used for C3.
For more information on the general procedure to design the filtering and driving stages of SAR ADCs, consult the TI Precision Designs 18-Bit, 1MSPS Data Acquisition Block (DAQ) Optimized for Lowest Distortion and Noise and 18-Bit Data Acquisition Block (DAQ) Optimized for Lowest Power, available for download at www.ti.com.