XR2209 Exar Corporation, XR2209 Datasheet - Page 12

• Manufacturer Part Number: XR2209
• Description: Voltage-Controlled Oscillator
• Manufacturer: Exar Corporation

Single Supply Operation
The circuit should be interconnected as shown in
Figure 14 for single supply operation. Pin 6 should be
grounded, and pin 5 biased from V
divider to a value of bias voltage between V
V
The frequency of operation is determined by the timing
capacitor C and the timing resistor R, and is equal to
1/RC. The squarewave output is obtained at pin 7 and
has a peak-to-peak voltage swing equal to the supply
voltage. This output is an “open-collector” type and
requires an external pull-up load resistor (nominally 5k )
to V+. The triangle waveform obtained at pin 8 is centered
about a voltage level V
where V
output swing of triangle wave is approximately equal to
V
CC
CC
XR-2209
/2.
/2.
Rev. 2.02
B
is the bias voltage at pin 5. The peak-to-peak
V
O
V
B
O
where:
1 F
0.6V
CC
V
V
CC
R
CC
TR
through a resistive
1
Figure 14. Single Supply Operation
C1
4
XR-2209
2
C
CC
C 2
/3 and
3
V
SWO
TWO
BIAS
EE
6
12
7
8
5
Frequency Control (Sweep and FM) - Split Supply
The circuit given in Figure 15 shows a frequency sweep
method for split supply operation.
The frequency of operation is controlled by varying the
total timing current, I
4. The timing current can be modulated by applying a
control voltage, V
resistor R.
negative, both the total timing current, I
oscillation frequency increase.
The frequency of operation, is now proportional to the
control voltage, V
V
5.1K
CC
R
L
Square Wave
Triangle Wave
Output
Output
As the control voltage becomes more
1 F
f
C
C
5.1K
, and determined as:
, to the timing pin through a series
T
, drawn from the activated timing pin
RC
1
1
V
CC
R
V
C
C
V
R
EE
Hz
T
, and the