DSPIC30F6011_06 Datasheet, PDF (145/228 Pages) Microchip Technology – High-Performance, 16-Bit Digital Signal Controllers

dsPIC30F6011/6012/6013/6014
19.13 Configuring Analog Port Pins
The use of the ADPCFG and TRIS registers control the
operation of the ADC port pins. The port pins that are
desired as analog inputs must have their correspond-
ing TRIS bit set (input). If the TRIS bit is cleared (out-
put), the digital output level (VOH or VOL) will be
converted.
The ADC operation is independent of the state of the
CH0SA<3:0>/CH0SB<3:0> bits and the TRIS bits.
When reading the Port register, all pins configured as
analog input channels will read as cleared.
Pins configured as digital inputs will not convert an ana-
log input. Analog levels on any pin that is defined as a
digital input (including the ANx pins) may cause the
input buffer to consume current that exceeds the
device specifications.
19.14 Connection Considerations
The analog inputs have diodes to VDD and VSS as ESD
protection. This requires that the analog input be
between VDD and VSS. 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 anti-
aliasing of the input signal. The R component should be
selected to ensure that the sampling time requirements
are satisfied. Any external components connected (via
high impedance) to an analog input pin (capacitor,
zener diode, etc.) should have very little leakage
current at the pin.
© 2006 Microchip Technology Inc.
DS70117F-page 143