38.10 Connection Considerations

Because the analog inputs employ Electrostatic Discharge (ESD) protection, they have diodes to V_DD and V_SS; therefore, the analog input must be between V_DD and V_SS. If the input voltage exceeds this range by greater than 0.3V (either direction), one of the diodes becomes forward biased, and it may damage the device if the input current specification is exceeded.

An external RC filter is sometimes added for antialiasing of the input signal. The R (resistive) component must be selected to ensure that the acquisition time is met. Any external components connected (through high-impedance) to an analog input pin (capacitor, Zener diode and so on) must have very little leakage current at the pin.