XR2209 Exar Corporation, XR2209 Datasheet - Page 13

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

If R = 2M , R
frequency sweep would result for a negative sweep
voltage V
The voltage to frequency conversion gain, K, is controlled
by the series resistance RC and can be expressed as:
The circuit of Figure 15 can operate both with positive
and negative values of control voltage. However, for
positive values of V
of the timing current I
stop.
Frequency Control (Sweep and FM) - Single Supply
The circuit given in Figure 16 shows the frequency sweep
method for single supply operation. Here, the oscillation
Rev. 2.02
C
K
V
EE
C
.
= 2k , C = 5000pF, then a 1000:1
V
C
f
C
T
with small (R
is reversed and the oscillations will
-
R
C
Figure 15. Frequency Sweep Operation, Split Supply
CV
1
EE
C
1 F
/R) ratio, the direction
I
O
Hz V
R
V
EE
V
R
V
CC
C
V
CC
T4
C
1
+
4
TC1
XR-2209
I
2
T
Voltage
Sweep
I
FM
V
C
or
C
C
V
13
EE
TC2
6
frequency is given as:
where V
This equation is valid from V
with R and I
where I
Caution: Total timing current I
frequency control range.
3
V
SWO
TWO
BIAS
C
-
T
T
7
8
5
= 0 and oscillation ceases.
= Vpin4 ~ Vbias + 0.7V.
f
T
V
is maximum to:
CC
V
R
1 F
L
C
RC
Square Wave
Triangle Wave
1
Output
Output
V
T
1
1
T
C
V
R
R
must be less than 6mA over the
EE
= 0V where R
C
R
R
1 –
C
XR-2209
V
V
C
T
C
is in parallel