LM3S612 Datasheet, PDF (345/419 Pages) List of Unclassifed Manufacturers – Microcontroller

LM3S612 Data Sheet
15
15.1
15.2
Analog Comparator
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
The LM3S612 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:
„ An individual external reference voltage
„ A shared single external reference voltage
„ A shared internal reference voltage
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 15-1. Analog Comparator Module Block Diagram
C0-
-ve input _{Comparator 0}
C0+
+ve input
output
C0o
+ve input (alternate)
ACCTL0
trigger
trigger
ACSTAT0
interrupt
reference input
interrupt
internal
bus
Voltage
Ref
ACREFCTL
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.
As shown in Figure 15-2, 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.
April 27, 2007
345
Preliminary