I want to use ADI's PH solution CN0326. I saw a piece of information about adding EDS protection to the input path of the AD8603. I don't know if this information is correct or necessary. If so, what is the principle it adopts? Please under guidance.
Please see below for information.
The circuit in Figure offers an alternative approach. An Analog Devices low-input-bias, low-offset-current AD8603 amplifier, IC1, serves as a unity-gain input buffer. For any normal input, the circuit's output voltage, VOUT, equals its input voltage, VIN. Thus, the voltage across ESD-protection diode D1A or D1B approaches 0V, and neither diode's leakage current affects the sensor's output signal. Depending on the polarity of an ESD event you apply to the circuit's input connector, its high-voltage spike discharges through diode D1A or D1B into the positive or the negative power-supply rail. Capacitor C1 acts as an intermediate "charge reservoir" that slows the ESD spike's rate of rise and protects IC1's output stage from latching until diode D2A or D2B begins diversion of the ESD transient into the positive or the negative supply rail. In effect, C1 compensates for D1's parasitic capacitance. Resistor R3 allows IC1 to drive the capacitive load that C1 presents without going into oscillation.
During an ESD event, both D1 and D2 can conduct, but the voltage at VIN exceeds the power-supply-rail voltage by only two forward-biased diode voltage drops. Resistors R1 and R2 limit the amplifier input's currents below the manufacturer's recommended 5-mA maximum rating.
When packaging the circuit, pay special attention to the pc board's layout. Imperfections in the board's dielectric properties can provide parasitic-leakage-current paths. Adding copper traces on both sides of the board to form guard rings around the circuit's high-impedance nodes diverts leakage currents .