3.3.5.3.2 Current Sensor Inputs Configuration when Using Shunt
The Shunt Resistor technique uses a small (shunt) resistor placed in the path of the load current. When the load current flows through this resistance, a small voltage drop is developed across it. This voltage drop is measured by an input of the AFE, which converts it into the corresponding current consumption.
Warning: A shunt resistor must be
placed in series with the line to be measured, then connected to the measurement inputs.
The demonstration board is referred to neutral; therefore, a shunt resistor can only be
used in neutral line. Using a shunt resistor to measure currents in lines 1 or 2 will
damage the board, and it is dangerous for the user.
For Shunt operation, the input network must only provide a first-order low-pass filter.
The filter must be tuned with the following component values:
- RA1, RA2 = Do Not Populate
- RB1, RB2 = 0Ω
- RC1, RC2 = 3 kΩ, 1%, 25 ppm/ºC
- CA1, CA2 = 47 pF Y7R
- CB1, CB2 = Do Not Populate
- CC1, CC2 = 3.3 nF NP0/COG
- D1, D2 = Si Junction diodes (recommended)