MCP6546-ILT Microchip Technology, MCP6546-ILT Datasheet - Page 12

• Manufacturer Part Number: MCP6546-ILT
• Description: Open-Drain Output Sub-Microamp Comparators
• Manufacturer: Microchip Technology

MCP6546/7/8/9
3.0
The MCP6546/7/8/9 family of open-drain output com-
parators are fabricated on Microchip’s state-of-the-art
CMOS process. They are suitable for a wide range of
applications requiring very low power consumption. A
0.1 mF bypass capacitor from the power supply pin to
ground is recommended.
3.1
The input stage of this family of devices uses two dif-
ferential input stages in parallel: one operates at low
input voltages and the other at high input voltages.
With this topology, the input voltage is +0.3V above
V
measured at both V
proper operation.
3.2
The comparator family uses CMOS transistors at the
input. They are designed to prevent phase inversion
when the input pins exceed the supply voltages.
Figure 2-37 shows an input voltage exceeding both
supplies with no resulting phase inversion.
The maximum operating input voltages that can be
applied are V
inputs that exceed this absolute maximum rating can
cause excessive current to flow and permanently dam-
age the device. In applications where the input pin
exceeds the specified range, external resistors can be
used to limit the current below ±2 mA, as shown in
Figure 3-1.
FIGURE 3-1:
should be used to limit excessive input current if
either of the inputs exceeds the Absolute
Maximum specification.
DS21714B-page 12
DD
V
and -0.3V below V
IN
APPLICATIONS INFORMATION
Rail-to-Rail Input
Input Voltage and Phase Reversal
R
R
IN
IN
SS
------------------------------------------------------------------------------ -
R
V
--------------------------------------------------------------------------- -
Maximum expected V
-0.3V and V
IN
SS
–
SS
Minimum expected V
An input resistor (R
-0.3V and V
SS
MCP654X
. The input offset voltage is
2 mA
2 mA
DD
+0.3V. Voltages on the
DD
IN
+0.3V to ensure
–
V
IN
DD
IN
V
)
OUT
3.3
Input offset voltage (V
(input-referred) low-high and high-low trip points. Input
hysteresis voltage (V
the same trip points. Hysteresis reduces output chatter-
ing when one input is slowly moving past the other, and
thus reduces dynamic supply current. It also helps in
systems where it is best not to cycle between states too
frequently (e.g., air conditioner thermostatic control).
The family has internally set hysteresis which is small
enough to maintain input offset accuracy (<7 mV), and
large enough to eliminate output chattering caused by
the comparator’s own input noise voltage (200 µVp-p).
FIGURE 3-2:
comparators’ internal hysteresis eliminates
output chatter caused by input noise voltage.
3.3.1
Figure 3-3 shows an inverting circuit for a single-supply
application using three resistors, besides the pull-up
resistor. The resulting hysteresis diagram is shown in
Figure 3-4.
FIGURE 3-3:
hysteresis.
-1
-2
-3
9
8
7
6
5
4
3
2
1
0
V
0
V
Hysteresis
IN
V
R
R
DD
DD
2
3
100
INVERTING CIRCUIT
V
= 5.0V
OUT
200
V
IN
300
Time (100 ms/div)
HYST
OS
MCP654X
The MCP6546/7/8/9
Inverting circuit with
400
) is the center (average) of the
V
2002 Microchip Technology Inc.
) is the difference between
DD
500
Hysteresis
R
600
F
V
700
PU
R
800
PU
V
900
OUT
1000
30
25
20
15
10
5
0
-5
-10
-15
-20
-25
-30