SBAS920 October 2018 AMC1302-Q1
The high-side power supply (VDD1) for the AMC1302-Q1 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 AMC1302-Q1 (INN). If a four-pin shunt is used, the inputs of the AMC1302-Q1 device 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 systems using single-ended input ADCs, Figure 53 shows an example of a TLV313-Q1-based signal conversion and filter circuit as used on the AMC1302EVM, where VCMADC is the common-mode input voltage of the ADC. Tailor the bandwidth of this filter stage to the bandwidth requirement of the system and use NP0-type capacitors for best performance.
For more information on the general procedure to design the filtering and driving stages of SAR ADCs, see 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.