Datasheet

bit in the GPIO Alternate Function Select (GPIOAFSEL) register (page 311) should be set to choose
the Analog Comparator function. The positive and negative input signal are configured by clearing
the DEN bit in the GPIO Digital Enable (GPIODEN) register. For more information on configuring
GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 289.
Table 17-1. Analog Comparators Signals (100LQFP)
DescriptionBuffer Type
a
Pin TypePin NumberPin Name
Analog comparator 0 positive input.AnalogI90C0+
Analog comparator 0 negative input.AnalogI92C0-
Analog comparator 0 output.TTLO91C0o
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
Table 17-2. Analog Comparators Signals (108BGA)
DescriptionBuffer Type
a
Pin TypePin NumberPin Name
Analog comparator 0 positive input.AnalogIA7C0+
Analog comparator 0 negative input.AnalogIA6C0-
Analog comparator 0 output.TTLOB7C0o
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
17.3 Functional Description
Important: It is recommended that the Digital-Input enable (the GPIODEN bit in the GPIO module)
for the analog input pin be disabled to prevent excessive current draw from the I/O
pads.
The comparator compares the VIN- and VIN+ inputs to produce an output, VOUT.
VIN- < VIN+, VOUT = 1
VIN- > VIN+, VOUT = 0
As shown in Figure 17-2 on page 648, the input source for VIN- is an external input. In addition to
an external input, input sources for VIN+ can be the +ve input of comparator 0 or an internal reference.
Figure 17-2. Structure of Comparator Unit
ACCTL
CINV
internal
bus
interrupt
trigger
TrigGen
output
ACSTAT
IntGen
- ve input
1
alternate+ ve input ( )
0
+ ve input
2
reference input
June 18, 2012648
Texas Instruments-Production Data
Analog Comparator
NRND: Not recommended for new designs.