Datasheet

MCP6546/6R/6U/7/8/9
DS21714G-page 18 © 2002-2012 Microchip Technology Inc.
4.9 Unused Comparators
An unused amplifier in a quad package (MCP6549)
should be configured as shown in Figure 4-8. This
circuit prevents the output from toggling and causing
crosstalk. It uses the minimum number of components
and draws minimal current (see Figure 2-15 and
Figure 2-18).
FIGURE 4-8: Unused Comparators.
4.10 Typical Applications
4.10.1 PRECISE COMPARATOR
Some applications require higher DC precision. An
easy way to solve this problem is to use an amplifier
(such as the MCP6041) to gain-up the input signal
before it reaches the comparator. Figure 4-9 shows an
example of this approach.
FIGURE 4-9: Precise Inverting
Comparator.
4.10.2 WINDOWED COMPARATOR
Figure 4-10 shows one approach to designing a
windowed comparator. The wired-OR connection
produces a high output (logic 1) when the input voltage
is between V
RB
and V
RT
(where V
RT
> V
RB
).
FIGURE 4-10: Windowed Comparator.
¼ MCP6549
V
DD
–
+
V
REF
V
DD
V
DD
R
1
R
2
V
OUT
V
IN
V
REF
V
PU
R
PU
MCP6546
MCP6041
V
RT
1/2
V
RB
V
IN
V
PU
R
PU
V
OUT
MCP6547
1/2
MCP6547