XR-2209CN View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'XR-2209CN' PDF : 20 Pages View PDF
XR-2209
VCC
VCC
C
1mF
RL
12
VCC C1
3
C 2 SWO 7
XR-2209
8
TWO
BIAS 5
Square Wave
Output
Triangle Wave
Output
VCC
5.1K
TR
VEE
4
6
5.1K
1mF
R
Figure 14. Single Supply Operation
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 VCC through a resistive
divider to a value of bias voltage between VCC/3 and
VCC/2.
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 5kW)
to V+. The triangle waveform obtained at pin 8 is centered
about a voltage level VO where:
VO + VB ) 0.6V
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, IT, drawn from the activated timing pin
4. The timing current can be modulated by applying a
control voltage, VC, to the timing pin through a series
resistor R. As the control voltage becomes more
negative, both the total timing current, IT, and the
oscillation frequency increase.
The frequency of operation, is now proportional to the
control voltage, VC, and determined as:
ƪ ƫ f
+
1
RC
1
)
VCR
RCVEE
Hz
where VB is the bias voltage at pin 5. The peak-to-peak
output swing of triangle wave is approximately equal to
VCC/2.
Rev. 2.02
12
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