LM339, LM339A, LM239, LM239A, LM2901, M2901V, MC3302

4

MOTOROLA ANALOG IC DEVICE DATA

Figure 7. Driving Logic

Figure 8. Squarewave Oscillator

Logic

Device

VCC

(V)

RL

k

Ω

CMOS

TTL

1/4 MC14001

1/4 MC7400

+15

+5.0

100

10

RS = Source Resistance

R1

] RS

T1 = T2 = 0.69 RC

f

[

7.2

C(

µF)

R2 = R3 = R4

R1

[ R2 // R3 // R4

–

+

+

–

VCC

Vin

Vref

VCC ≥ 4.0 V

VCC

+

C

330 k

R4

330 k

R3

R1

100 k

10 k

R1

T1

T2

VCC

VO

RS

RL

R2

330 k

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 k

Ω 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.

10

Figure 9. Zero Crossing Detector

(Single Supply)

Figure 10. Zero Crossing Detector

(Split Supplies)

Vin(min) ≈ 0.4 V peak for 1% phase distortion (∆Θ).

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

R1 + R2 = R3

R3

≤

R5

for small error in zero crossing

Vin

10 k

D1

R1

8.2 k

6.8 k

R2

15 k

R3

+15 V

*

Θ

VCC

10 k

Vin

VEE

Vin

Vin(min)

VCC

VO

VEE

∆Θ

Θ

*

)

10 M

R5

220 k

R4

220 k

VO

VO

+