MCP6546T-I/P Microchip Technology, MCP6546T-I/P Datasheet - Page 12

• Manufacturer Part Number: MCP6546T-I/P
• Description: Push-Pull Output Sub-Microamp Comparator
• 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.
The power supply pin needs to be by-passed with a
0.1 µF capacitor.
3.1
The input stage of this family of devices uses two differ-
ential input stages in parallel: one operates at low input
voltages, and the other at high input voltages. With this
topology, the family operates to 0.3V past both rails.
The input offset voltage is measured at both V
and V
3.2
The comparator family uses CMOS transistors at the
input. They are designed to not exhibit 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 in or out of the input
pins. Current beyond ±2 mA can cause possible reli-
ability problems. Applications that exceed this rating
must be externally limited with an input resistor as
shown in Figure 3-1.
FIGURE 3-1:
to limit excessive input current if either of the inputs
exceeds the Absolute Maximum specification.
3.3
Input offset voltage (V
(input referred) low-high and high-low trip points. Input
hysteresis voltage (V
same trip points. Hysteresis reduces output chattering
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).
DS21714A-page 12
V
DD
IN
+0.3V to ensure proper operation.
APPLICATIONS INFORMATION
Rail to Rail Input
Input Voltage and Phase Reversal
Hysteresis
R
R
IN
IN
SS
------------------------------------------------------------------------------ -
R
V
--------------------------------------------------------------------------- -
-0.3V and V
Maximum expected V
An input resistor (R
IN
SS
–
HYST
OS
Minimum expected V
) is the center (average) of the
) is the difference between the
MCP654X
2 mA
2 mA
DD
+0.3V. Voltages on the
IN
IN
) should be used
–
V
IN
DD
V
OUT
SS
-0.3V
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:
internal hysteresis eliminates output chatter caused by
input noise voltage.
3.3.1
Figure 3-3 shows an inverting circuit for single supply
using three resistors, besides the pull-up resistor. The
resulting hysteresis diagram is shown in Figure 3-4.
FIGURE 3-3:
FIGURE 3-4:
circuit.
V
V
V
V
OL
SS
PU
H
-1
-2
-3
V
9
8
7
6
5
4
3
2
1
0
V
SS
0
V
IN
INVERTING CIRCUIT
R
R
V
DD
Low to High
OUT
2
3
= 5.0V
100
V
V
OUT
DD
200
The
Inverting circuit with hysteresis.
Hysteresis diagram for the inverting
V
IN
300
V
MCP654X
Time (100 ms/div)
MCP6546/7/8/9
TLH
400
V
2002 Microchip Technology Inc.
DD
V
500
THL
R
600
High to Low
Hysteresis
F
V
700
PU
R
800
PU
comparators’
V
V
DD
900
OUT
1000
30
25
20
15
10
5
0
-5
-10
-15
-20
-25
-30
V
IN