LM339, LM339A, LM239, LM239A, LM2901, M2901V, MC3302
Figure 7. Driving Logic
VCC
Figure 8. Squarewave Oscillator
VCC
≥
4.0 V
100 k
+
C
R2
VCC
–
+
R3
330 k
R4
RL
kΩ
100
10
330 k
R1
VO
VCC
T1
10 k
Vin
Vref
RS
+
–
RL
R1
RS = Source Resistance
R1 RS
Logic
CMOS
TTL
Device
1/4 MC14001
1/4 MC7400
VCC
(V)
+15
+5.0
]
330 k
T2
T1 = T2 = 0.69 RC
7.2
f
C(µF)
[
R2 = R3 = R4
R1 R2 // R3 // R4
[
APPLICATIONS INFORMATION
These quad comparators feature high gain, wide
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 (VOL to VOH). To alleviate this
situation input resistors < 10 kΩ should be used. The
Figure 9. Zero Crossing Detector
(Single Supply)
+15 V
R4
220 k
6.8 k
R2
R5
220 k
addition of positive feedback (< 10 mV) is also
recommended. It is good design practice to ground all
unused input pins.
Differential input voltages may be larger than supply
voltages without damaging the comparator’s inputs.
Voltages more negative than –300 mV should not be used.
Figure 10. Zero Crossing Detector
(Split Supplies)
Vin(min)
≈
0.4 V peak for 1% phase distortion (∆Θ).
Vin
Vin(min)
R1
8.2 k
Vin
D1
*
)
10 M
10 k
VO
VCC
Θ
10 k
VO
*
Vin
+
VEE
15 k
R3
VCC
VO
VEE
∆Θ
Θ
D1 prevents input from going negative by more than 0.6 V.
R1 + R2 = R3
R3
≤
R5
for small error in zero crossing
10
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