LM3S101-CRN20-XNPT Luminary Micro, Inc., LM3S101-CRN20-XNPT Datasheet - Page 251

• Manufacturer Part Number: LM3S101-CRN20-XNPT
• Description: Microcontroller
• Manufacturer: Luminary Micro, Inc.

Analog Comparators
13
13.1
13.2
251
Analog Comparators
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
The LM3S101 controller provides two independent integrated analog comparators that can be
configured to drive an output or generate an interrupt.
A comparator can compare a test voltage against any one of these voltages:
The comparator can provide its output to a device pin, acting as a replacement for an analog
comparator on the board, or it can be used to signal the application via interrupts to cause it to
start capturing a sample sequence. The interrupt generation logic is separate.
Block Diagram
Figure 13-1.
Functional Description
Important:
The comparator compares the VIN- and VIN+ inputs to produce an output, VOUT.
As shown in Figure 13-2, 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.
An individual external reference voltage
A shared single external reference voltage
A shared internal reference voltage
If a comparator input is configured as an analog input that is not a full scale value
(0 V or 3.3 V only), the input Schmitt Trigger is required to be disabled via the GPIO
module.
Analog Comparator Block Diagram
<none>
internal
C0+
C1-
C0-
bus
ACREFCTL
Voltage
Ref
Preliminary
-ve input
+ve input
+ve input (alternate)
reference input
-ve input
+ve input
+ve input (alternate)
reference input
ACSTAT1
ACSTAT0
ACCTL1
ACCTL0
Comparator 1
Comparator 0
interrupt
interrupt
output
output
<none>
interrupt
C0o
interrupt
March 22, 2006