MCP6549 Microchip Technology, MCP6549 Datasheet - Page 13

• Manufacturer Part Number: MCP6549
• Description: (MCP6546 - MCP6549) Open-Drain Output Sub-Microamp Comparators
• Manufacturer: Microchip Technology

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3.4.1
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.
FIGURE 3-4:
inverting circuit.
In order to determine the trip voltages (V
for the circuit shown in Figure 3-3, R
simplified to the Thevenin equivalent circuit with
respect to V
FIGURE 3-5:
V
V
2003 Microchip Technology Inc.
V
V
V
V
TLH
THL
V
OH
OL
SS
V
PU
V
IN
R
R
V
DD
23
= trip voltage from low to high
= trip voltage from high to low
2
3
SS
Low-to-High
V
OUT
INVERTING CIRCUIT
DD
, as shown in Figure 3-5.
R
23
MCP654X
V
V
TLH
DD
Inverting circuit with
Hysteresis diagram for the
Thevenin Equivalent Circuit.
+
-
MCP654X
V
THL
I
R
RF
F
I
PU
High-to-Low
I
R
OL
F
V
2
PU
and R
R
THL
V
R
V
PU
DD
PU
PU
and V
V
V
3
OUT
OUT
can be
V
IN
TLH
)
Where:
Using this simplified circuit, the trip voltage can be
calculated using the following equation:
EQUATION
Figure 2-19 and Figure 2-22 can be used to determine
typical values for V
output current I
can be determined using the equation below:
EQUATION
V
EQUATION
As explained in Section 3.1, “Comparator Inputs”, it is
important to keep the non-inverting input below
V
3.5
With this family of comparators, the power supply pin
(V
capacitor (i.e., 0.01 µF to 0.1 µF) within 2 mm for good
edge rate performance.
3.6
Reasonable capacitive loads (e.g., logic gates) have
little impact on propagation delay (see Figure 2-27).
The supply current increases with increasing toggle
frequency
capacitive loads.
V
V
V
OH
DD
TH L
DD
TLH
THL
+0.3V when V
can be calculated using the equation below:
for single supply) should have a local bypass
=
= trip voltage from low to high
= trip voltage from high to low
V
V
TLH
V
Supply Bypass
Capacitive Loads
O H
PU
I
OL
(Figure 2-30),
=
=
--------------------------------------- -
R
=
OL
23
V
MCP6546/7/8/9
V
V
OL
+
PU
23
as shown in Figure 3-3. This current
PU
V
------------------------- -
OL
I
R
O L
PU
R
R
---------------------- -
R
=
. This voltage is dependent on the
–
23
> V
F
R
23
23
V
–
PU
+
=
R
------------------
R
=
23
+
V
DD
23
2
R
I
R
O L
+
R
PU
------------------
R
PU
3
.
R
F
2
R
especially
2
+
+
3
+
------------------------------------- -
R
R
+
+
I
R
23
3
RF
V
----------------------- -
3
V
V
V
R
R
+
23
DD
23
23
23
23
R
DS21714C-page 13
–
+
+
F
---------------------------------------
R
--------------------- -
R
V
23
23
+
R
R
OL
R
R
F
F
R
+
with
+
F
F
PU
R
R
+
F
F
R
+
PU
higher
R
PU