XR-2209
6
Rev. 2.02
R
L
Square Wave
Output
Triangle Wave
Output
S2
C
1 F
I+
R
6
BIAS
5
TWO
8
SWO
7
C2
3
C1
2
1
XR-2209
S1
TR
1 F
I-
10K
D1
1 F
Figure 4. Test Circuit for Split Supply Operation
V
CC
V
CC
V
CC
V
EE
V
EE
V
EE
4
OPERATING CONSIDERATIONS
Supply Voltage (Pins 1 and 6)
The XR-2209 is designed to operate over a power supply
range of 4V to 13V for split supplies, or 8V to 26V for
single supplies. Figure 5shows the permissible supply
voltage for operation with unequal split supply voltages.
Figure 6and Figure 7show 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
T
flows out of this
terminal, where I
T
is the total timing current.
Bias for Single Supply (Pin 5)
For single supply operation, pin 5 should be externally
biased to a potential between V
CC
/3 and V
CC
/2V (see
Figure 3.) The bias current at pin 5 is nominally 5% of the
total oscillation timing current, I
T
.
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
T
,
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 to 200k (see Figure 8
Figure 9 Figure 10and Figure 11.) To avoid parasitic
pick up, timing resistor leads should be kept as short as
possible.