LM339, LM339E, LM239, LM2901, LM2901E, LM2901V, NCV2901, MC3302

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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

situation input resistors < 10 k

W should be used. The

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.

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Figure 9. Zero Crossing Detector

(Single Supply)

Figure 10. Zero Crossing Detector

(Split Supplies)

D1 prevents input from going negative by more than 0.6 V.

R1 + R2 = R3

R3

≤

R5

for small error in zero crossing

10 k

D1

R1

8.2 k

6.8 k

R2

15 k

R3

+15 V

*

q

10 k

Dq

q

*

)

10 M

R5

220 k

R4

220 k

+