XR2209 Exar Corporation, XR2209 Datasheet - Page 6

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

OPERATING CONSIDERATIONS
Supply Voltage (Pins 1 and 6)
The XR-2209 is designed to operate over a power supply
range of
single supplies. Figure 5 shows the permissible supply
voltage for operation with unequal split supply voltages.
Figure 6 and Figure 7 show supply current versus supply
voltage. Performance is optimum for 6V split supply, or
12V single supply operation. At higher supply voltages,
the frequency sweep range is reduced.
Ground (Pin 6)
For split supply operation, this pin serves as circuit
ground. For single supply operation, pin 6 should be ac
grounded through a 1 F bypass capacitor. During split
supply operation, a ground current of 2 I
terminal, where I
XR-2209
Rev. 2.02
4V to
V
T
EE
13V for split supplies, or 8V to 26V for
is the total timing current.
1 F
S1
V
V
R
CC
CC
Figure 4. Test Circuit for Split Supply Operation
TR
1
C 1
4
I+
XR-2209
2
T
flows out of this
C
C 2
3
V
SWO
TWO
EE
BIAS
6
I-
6
7
8
5
Bias for Single Supply (Pin 5)
For single supply operation, pin 5 should be externally
biased to a potential between V
Figure 3. ) The bias current at pin 5 is nominally 5% of the
total oscillation timing current, I
Bypass Capacitors
The recommended value for bypass capacitors is 1 F
although larger values are required for very low frequency
operation.
Timing Resistor (Pin 4)
The timing resistor determines the total timing current, I
available to charge the timing capacitor. Values for the
timing resistor can range from 2k to 2M ; however, for
optimum temperature and power supply stability,
recommended values are 4k
Figure 9 , Figure 10 and Figure 11. ) To avoid parasitic
pick up, timing resistor leads should be kept as short as
possible.
10K
1 F
R
L
Square Wave
Triangle Wave
S2
Output
Output
V
EE
V
CC
D1
1 F
T
to 200k
.
CC
/3 and V
(see Figure 8 ,
CC
/2V (see
T
,