LM393, LM393A, LM293, LM2903, LM2903V
APPLICATIONS INFORMATION
These dual comparators feature high gain, wide
The addition of positive feedback (<10 mV) is also
recommended. It is good design practice to ground all
unused pins.
Differential input voltages may be larger than supply
voltage without damaging the comparator’s inputs. Voltages
more negative than –0.3 V should not be used.
bandwidth characteristics. This gives the device oscillation
tendencies if the outputs are capacitively coupled to the
inputs via stray capacitance. This oscillation manifests itself
during output transitions (V
situation, input resistors <10 kΩ should be used.
to V
). To alleviate this
OL
OH
Figure 7. Zero Crossing Detector
(Single Supply)
Figure 8. Zero Crossing Detector
(Split Supply)
+15 V
V
in(min)
V
in
R4
220 k
R5
220 k
R1
8.2 k
10 k
+V
CC
Θ
Θ
V
in
R1
D1
LM393
6.8 k
R2
10 k
LM393
V
V
V
in
CC
15 k
R3
10 M
O
–V
EE
∆Θ
D1 prevents input from going negative by more than 0.6 V.
– V
EE
R1 + R2 = R3
R5
V
0.4 V peak for 1% phase distortion (∆Θ).
in(min)
R3
≤
for small error in zero crossing.
10
Figure 10. Time Delay Generator
Figure 9. Free–Running Square–Wave Oscillator
1.0 MΩ
V
CC
V
V
CC
CC
R
10 k
L
t
R
R
L
–
–
–
V
CC
0.001 µF
LM393
V
LM393
O
LM393
+
V
+
C
+
+
C
V
O
51 k
+ V
ref
V
51 k
CC
‘‘ON’’ for t
where:
t
∆t
O
51 k
V
V
ref
in
V
O
V
0
ref
)
∆
t = RC n (
V
0
O
V
CC
0
t
V
t
V
C
0
ref
t
O
Figure 11. Comparator with Hysteresis
V
CC
R
= R1 | | R2
S
R
R
L
S
–
(V
–V ) R1
R1 + R2 + R
CC ref
V
= V
+
–
th1
ref
ref
LM393
L
+
(V –V Low) R1
ref
O
V
= V
th2
R1
R1 + R2
V
ref
R2
5
MOTOROLA ANALOG IC DEVICE DATA
ONSEMI [ ONSEMI ]
