10

LM393/LM339

36V Low Power Dual/Quad Differential Comparators

www.3peakic.com.cn

Rev. B.2

3

R

||

2

R

1

R

3

R

||

2

R

DD

V

A2

V







comparator switches again, bringing it back to the initial stage. The time period is equal to twice the time it takes to

1

C

4

R

ln2

2

1

Freq









LM393

t

t

Figure 7. Relaxation Oscillator

Windowed Comparator

Figure 8 shows one approach to designing a windowed comparator using a single LM393/339 chip. Choose different

thresholds by changing the values of R1, R2, and R3. OutA provides an active-low undervoltage indication, and OutB

gives an active-low overvoltage indication. ANDing the two outputs provides an active-high, power-good signal. When

1

)/R

3

R

2

R

1

(R

r

V

OH

V









)

2

R

1

)/(R

3

R

2

R

1

(R

r

V

UH

V











Figure 8. Windowed Comparator