MC14578P(2000) Ver la hoja de datos (PDF) - Motorola => Freescale
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MC14578P Datasheet PDF : 8 Pages
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MC14578
V+
Freescale Semiconductor, Inc.
APPLICATIONS INFORMATION
V+
1
VDD
MC14578
2
COMP OUT
3
IN A
16
NC
15
IN +
14
NC
R1
V+
R3
R2
R5
6.8 k
LOW–BATTERY
INDICATOR
D2
4
IN B
5
OUT A
6
OUT B
7
IN C
8
OUT C1
13
BUFF OUT
* 12
IN
11
Rbias
10
VSS
9
OUT C2
R4
3.9 M
V+
D1
HIGH = BATTERY LOW
OUTPUT LOW = BATTERY OK
* NOTE: IN + and IN have very high input impedance. Interconnect to these pins should be as short as possible.
Figure 1. Low–Battery Detector
EXAMPLE VALUES
Near the switchpoint, the comparator output in the circuit
of Figure 1 may chatter or oscillate. This oscillation appears
on the signal labelled OUTPUT. In some cases, the oscilla-
tion in the transition region will not cause problems. For
example, an MPU reading OUTPUT could sample the signal
two or three times to ensure a solid level is attained. But, in a
low battery detector, this probably is not necessary.
To eliminate comparator chatter, hysteresis can be added
as shown in Figure 2. The circuit of Figure 2 requires slightly
more operating current than the Figure 1 arrangement.
R1
470 kΩ
820 kΩ
1.2 MΩ
R2
1.3 MΩ
1.2 MΩ
1.2 MΩ
R3
20 kΩ
39 kΩ
62 kΩ
Nominal Trip Point
4.08 V
5.05 V
6.00 V
12
–
2
+
R6
15
R7
Figure 2. Adding Hysteresis
4
For More Information On This Product, Motorola Sensor Device Data
Go to: www.freescale.com
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