PRODUCT SPECIFICATION
RC2207
0.1
µF
+V
S
Binary Keying
Inputs
0.1
µF
3.9K
9
10
11
5.1K
12
6
R3
+V
S
S1
65-2207-10
I
S
1
2
C
S2
+V
S
3
13
14
5
R
L
Squarewave
Output
Trianglewave
Output
8
RC2207
Device
Under Test
7
R4
4
R1
R2
Figure 8. Test Circuit for Single Supply Operation
For single supply operation, the DC voltage at pin 10 and the
timing terminals (pins 4 through 7) are equal and approxi-
mately 0.6V above V
B
, the bias voltage at pin 11 . The logic
levels at the binary keying terminals are referenced to the
voltage at pin 10.
Pulse and Sawtooth Operation
The duty cycle of the output waveforms can be controlled by
frequency shift keying at the end of every half cycle of
oscillator output. This is accomplished by connecting one or
both of the binary keying inputs (pin 8 or 9) to the square-
wave output at pin 13. The output waveforms can then be
converted to positive or negative pulses and sawtooth
waveform.
Figure 10 is the recommended circuit connection for duty
cycle control. Pin 8 is shorted to pin 13 so that the circuit
switches between the 0 0 and the 1 0 logic states given in
Table 1. Timing pin 5 is activated when the output is high,
and pin 6 is activated when the squarewave output goes to a
low state.
The duty cycle of the output waveforms given as:
R2
Duty Cycle = --------------------
-
R2 + R3
On-Off Keying
The RC2207 can be keyed on and off by simply activating an
open circuited timing pin. Under certain conditions, the cir-
cuit may exhibit very low frequency (<1 Hz) residual oscilla-
tion in the off state due to internal bias current. If this effect
is undesirable, it can be eliminated by connecting a 10 MΩ
resistor from pin 3 to + V
S
.
Frequency Control
(Sweep and FM)
The frequency of operation is controlled by varying the total
timing current, I
T
, drawn from the activated timing pin 4, 5,
6 or 7. The timing current can be modulated by applying a
control voltage, V
C
, to the activated timing pin through a
series resistor R
C
as shown in Figure 9.
For split supply operation, a negative control voltage, V
C
,
applied to the circuit of Figure 9 causes the total timing
current, I
T
, and the frequency, to increase.
As an example, in the circuit of Figure 9, the binary keying
inputs are grounded. Therefore, only timing pin 6 is
activated.
The frequency of operation determined by:
V
C
R3
1
-
-
f = -------------- 1 – --------------------------- Hz
R3C
B
(
R
C
) (
–V
C
)
and can be varied from 0.1% to 99.9% by proper choice of
timing resistors. The frequency of oscillation, f, is given as:
2
1
-
-
f = --- --------------------
C R2 + R3
The frequency can be modulated or swept without changing
the duty cycle by connecting R2 and R3 to a common control
voltage V
C
instead of to -V
S
. The sawtooth and the pulse
output waveforms are shown in the Typical Performance
Characteristics Graphs.
7
RAYTHEON [ RAYTHEON COMPANY ]
