LM3S315 Luminary Micro, Inc., LM3S315 Datasheet - Page 309

• Manufacturer Part Number: LM3S315
• Description: Microcontroller
• Manufacturer: Luminary Micro, Inc.

14
14.1
14.2
April 27, 2007
Analog Comparator
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
The LM3S315 controller provides one analog comparator that can be configured to drive an output
or generate an interrupt or ADC event.
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 or triggers to the
ADC to cause it to start capturing a sample sequence. The interrupt generation and ADC triggering
logic is separate. This means, for example, that an interrupt can be generated on a rising edge and
the ADC triggered on a falling edge.
Block Diagram
Figure 14-1. Analog Comparator Module Block Diagram
Functional Description
Important:
The comparator compares the VIN- and VIN+ inputs to produce an output, VOUT.
As shown in Figure 14-2, 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
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.
internal
C0+
C0-
bus
ACREFCTL
Voltage
Ref
Preliminary
-ve input
+ve input
+ve input (alternate)
reference input
ACSTAT0
ACCTL0
Comparator 0
interrupt
trigger
output
C0o
trigger
interrupt
LM3S315 Data Sheet
309