
NCS2004
http://onsemi.com
11
APPLICATIONS
+
R1
R2
VO
Vref
Vin
VOH
VO
VOL
Hysteresis
VinL
VinH
Vref
MC1403
NCS2004
+
R1
VDD
VO
2.5 V
R2
50 k
10 k
Vref
5.0 k
R
C
R
C
+
VO
For: fo = 1.0 kHz
R = 16 kW
C = 0.01 mF
VDD
NCS2004
Figure 31. Voltage Reference
Figure 32. Wien Bridge Oscillator
Figure 33. Comparator with Hysteresis
VO + 2.5 V(1 )
R1
R2
)
Vref +
1
2
VDD
fO +
1
2pRC
VinL +
R1
R1 ) R2
(VOL * Vref) ) Vref
VinH +
R1
R1 ) R2
(VOH * Vref) ) Vref
H +
R1
R1 ) R2
(VOH * VOL)
For less than 10% error from operational amplifier,
((QO fO)/BW) < 0.1 where fo and BW are expressed in Hz.
If source impedance varies, filter may be preceded with
voltage follower buffer to stabilize filter parameters.
Given: fo = center frequency
A(fo) = gain at center frequency
Choose value fo, C
Vin
Figure 34. Multiple Feedback Bandpass Filter
+
VDD
R3
R1
R2
Vref
C
VO
CO = 10 C
CO
NCS2004
Then :
R3 +
Q
pfO C
R1 +
R3
2A(fO)
R2 +
R1 R3
4Q2 R1 * R3