NCV2002 ON Semiconductor, NCV2002 Datasheet - Page 13

• Manufacturer Part Number: NCV2002
• Description: Sub−one Volt Rail−to−rail Operational Amplifier with Enable Feature
• Manufacturer: ON Semiconductor

0.9 V
V
CC
1.0 nF
470 k
1.0 nF
470 k
R
R
C
C
1a
1a
T
T
470 k
R
1b
1.0 M
R
470 k
cww
cw
1b
470 k
−
+
0.9 V
R
10 k
10 k
470 k
T
−
+
R
V
2
CC
470 k
R
Figure 38. Variable Duty Cycle Pulse Generator
2
1N4148
1N4148
Figure 37. 0.9 V Square Wave Oscillator
D
D
1
2
f
O
http://onsemi.com
= 1.5 kHz
f
O
The timing capacitor C
through diode D
signal can be programmed by adjusting the value of the trimpot. The ca-
pacitor voltage will oscillate between 1/3 and 2/3 of V
resistors at the non−inverting input are of equal value.
Timing Capacitor
Timing Capacitor
13
Output Voltage
Output Voltage
Timing Capacitor
Output Voltage
Voltage
Voltage
The non−inverting input threshold levels are set so that
the capacitor voltage oscillates between 1/3 and 2/3 of
V
equal value. The following formula can be used to
approximate the output frequency.
CC
. This requires the resistors R
1
Voltage
, allowing a variable duty cycle. The pulse width of the
0.67 V
0.33 V
0.67 V
0.33 V
T
will charge through diode D
V
V
0.33 V
0.67 V
CC
CC
CC
CC
CC
CC
f
O
0
0
Counter−Clock−wise, High Duty Cycle
+
V
CC
CC
CC
1.39 R
0
Clock−wise, Low Duty Cycle
1
T
1a
C
T
, R
1b
and R
2
CC
and discharge
, since all the
2
to be of