LM3S300-IQN25-C2 Datasheet, PDF (438/498 Pages) Texas Instruments – Stellaris LM3S300 Microcontroller

Analog Comparators
NRND: Not recommended for new designs.
Table 13-1. Analog Comparators Signals (48QFP) (continued)
Pin Name
Pin Number Pin Type Buffer Type^a Description
C1+
13
I
Analog Analog comparator 1 positive input.
C1-
43
I
Analog Analog comparator 1 negative input.
C1o
13
O
TTL
Analog comparator 1 output.
C2+
12
I
Analog Analog comparator 2 positive input.
C2-
11
I
Analog Analog comparator 2 negative input.
C2o
12
O
TTL
Analog comparator 2 output.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
13.3 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 13-2 on page 438, 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 13-2. Structure of Comparator Unit
-ve input
+ve input ⁰
1
+ve input (alternate)
2
reference input
CINV
output
IntGen
ACCTL
ACSTAT
A comparator is configured through two status/control registers (ACCTL and ACSTAT ). The internal
reference is configured through one control register (ACREFCTL). Interrupt status and control is
configured through three registers (ACMIS, ACRIS, and ACINTEN). The operating modes of the
comparators are shown in the Comparator Operating Mode tables.
Typically, the comparator output is used internally to generate controller interrupts. It may also be
used to drive an external pin.
438
June 18, 2012
Texas Instruments-Production Data