Electronics
Semiconductor Division
RC2207
Voltage Controlled Oscillator
Features
•
•
•
•
•
•
•
•
•
•
Excellent temperature stability — 20 ppm/
°
C
Linear frequency sweep
Adjustable duty cycle — 0.1% to 99.9%
Two or four level FSK capability
Wide sweep range — 1000:1 min.
Logic compatible input and output levels
Wide supply voltage range —
±
4V to
±
13V
Low supply sensitivity
±
0.15%/V
Wide frequency range — 0.01 Hz to 1 MHz
Simultaneous triangle and squarewave outputs
Description
The RC2207 is a monolithic voltage-controlled oscillator
(VCO) integrated circuit featuring excellent frequency
stability and a wide tuning range. The circuit provides
simultaneous triangle and squarewave outputs over a
frequency range of 0.01 Hz to 1 MHz. It is ideally suited for
FM, FSK and sweep or tone generation as well as for
phase-locked loop applications.
As shown in the Block Diagram, the circuit is comprised of
four functional blocks: a variable-frequency oscillator which
generates the basic periodic waveforms; four current
switches actuated by binary keying inputs; and buffer
amplifiers for both the triangle and squarewave outputs.
The internal switches transfer the oscillator current to any
of four external timing resistors to produce four discrete
frequencies which are selected according to the binary logic
levels at the keying terminals (pins 8 and 9).
The RC2207 has a typical drift specification of 20 ppm/
°
C.
The oscillator frequency can be linearly swept over a 1000:1
range with an external control voltage; and the duty cycle of
both the triangle and the squarewave outputs can be varied
from 0.1% to 99.9% to generate stable pulse and sawtooth
waveforms.
Applications
•
•
•
•
FSK generation
Voltage and current-to-frequency conversion
Stable phase-locked loop
Waveform generation triangle, sawtooth, pulse,
squarewave
• FM and sweep generation
Block Diagram
A1
TIMING CAPACITOR
VCO
A2
–V
S
TRIANGLE WAVE OUTPUT
SQUARE WAVE OUTPUT
TIMING RESISTORS
R1-R4
CURRENT
SWITCH
BINARY KEY INPUTS
65-2207-01
Rev. 1.0.0
RC2207
PRODUCT SPECIFICATION
Pin Assignments
+V
S
Timing
Capacitor
R1
Timing
Resistors
R2
R3
R4
1
2
3
4
5
6
7
14
13
12
11
10
9
8
65-2207-02
Trianglewave Output
Squarewave Output
+V
S
Bias
GND
Binary
Keying
Inputs
Pin Descriptions
Pin Name
Bias for Single
Supply
Binary Keying
Inputs
Ground
Pin Number
11
Pin Function Description
For single supply operations, pin 11 should be externally biased to a
potential between +V
S
/3 and +V
S
/2 (see Figure 8). The bias current at pin
11 is nominally 5% of the total oscillation timing current I
T
.
The internal impedance at these pins is approximately 5 k
Ω
. Keying levels
are <1.4V for zero and > 3V for one logic levels referenced to the DC voltage
at pin 10.
For split supply operation, this pin serves as circuit ground. For single supply
operation, pin 10 should be AC grounded through a 1
µ
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.
The squarewave output at pin 13 is an open-collector stage capable of
sinking up to 20 mA of load current. R
L
serves as a pull-up load resistor for
this output. Recommended values for R
L
range from 1 k
Ω
to 10 k
Ω
The RC2207 is designed to operate over a power supply range of +4V to
±
13V for split supplies, or 8V to 26V for single supplies. At high supply
voltages, the frequency sweep range is reduced. Performance is optimum
for
±
6V, or 12V single supply operation.
The oscillator frequency is inversely proportional to the timing capacitor, C.
The minimum capacitance value is limited by stray capacitances and the
maximum value by physical size and leakage current considerations.
Recommended values range from 100 pF to 100
µ
F. The capacitor should
be non-polarized.
The timing resistors determine the total timing current, I
T
, available to
charge the timing capacitor. Values for timing resistors can range from 1.5
k
Ω
to 2 M
Ω
; however, for optimum temperature and power supply stability,
recommended values are 4 k
Ω
to 200 k
Ω
. To avoid parasitic pick up, timing
resistor leads should be kept as short as possible. For noise environments,
unused or deactivated timing terminals should be bypassed to ground
through 0.1
µ
F capacitors. Otherwise, they may be left open.
The output at pin 14 is a trianglewave with a peak swing of approximately
one-half of the total supply voltage. Pin 14 has a very low output impedance
of 10
Ω
and is internally protected against short circuits.
Notice that the triangle waveform linearity is sensitive to parasite coupling
between the square and the trianglewave outputs (pins 13 and 14). In board
layout or circuit wiring, care should be taken to minimize stray wiring
capacitance between those pins.
8, 9
10
Squarewave
Output
Supply Voltage
(+V
S
, –V
S
)
13
1, 12
Timing Capacitor
2, 3
Timing Resistors
(R1–R4)
4–7
Trianglewave
Output
14
2
PRODUCT SPECIFICATION
RC2207
Absolute Maximum Ratings
Parameter
Supply Voltage
Storage Temperature Range
Operating Temperature Range
Lead Soldering Temperature (60 seconds)
-65
-55
Min.
Max.
+26
+150
+125
+300
Units
V
V
°
C
°
C
Thermal Characteristics
Ceramic DIP
Maximum Juncton Temperature
Maximum P
D
T
A
< 50
°
C
Thermal Resistance,
θ
JC
Thermal Resistance,
θ
JA
For T
A
> 50
°
C Derate at
+175
°
C
1042 mW
60
°
C/W
120
°
C/W
8.33 mW/
°
C
SOIC
+125
°
C
300 mW
60
°
C/W
200
°
C/W
5.0 mW/
°
C
Plastic DIP
+125
°
C
468 mW
60
°
C/W
160
°
C/W
6.25 mW/
°
C
3
RC2207
PRODUCT SPECIFICATION
(Test Circuit of Figure 1, V
S
=
±
6V, T
A
= +25
°
C, C = 5000 pF, R1= R2 = R3 = R4 = 20 k
Ω
, R
L
= 4.7
Ω
binary inputs
grounded, S1 and S2 closed unless otherwise specified)
Parameters
General Characteristics
Supply Voltage
Single Supply
Split Supplies
Supply Current
Single Supply
Split
Supplies
Positive
Negative
Binary Keying Inputs
Switching Threshold
Input Resistance
Oscillator Section—Frequency Characteristics
Upper Frequency Limit
Lower Practical Frequency
Frequency Accuracy
Frequency Matching
Frequency
Stability
Sweep Range
Sweep Linearity
10:1 Sweep
1
1000:1 Sweep
FM Distortion
Recommended Range of Timing Resistors
Impedance at Timing Pins
DC Level at Timing Terminals
Output Characteristics
Triangle output
Amplitude
Impedance
DC Level
Linearity
Squarewave
Output
Amplitude
Saturation Voltage
Rise Time
Fall Time
Note:
1. Guaranteed by design.
Electrical Characteristics
Test Conditions
See Typical Performance
Characteristics
Measured at pin 1,
S1 open (See Fig. 8)
Measured at pin 1,
S1 open (See Fig. 7)
Measured at pin 12,
S1, S2 open
RC2207
RM2207
RC2207
RM2207
Min.
+8.0
±
4
Typ.
+12
±
6
5.0
5.0
Max.
+26
±
13
7.0
7.0
8.0
7.0
Units
V
V
mA
mA
mA
4.0
1.4
2.2
5.0
6.0
2.8
V
k
Ω
MHz
Hz
±
3.0 % of f
0
% of f
0
50
ppm/
°
C
%/V
f
H
/f
L
Measured at pins 8 and 9.
Refer to pin 10.
C = 500 pF, R3 = 2 k
Ω
C = 50
µ
F, R3 = 2 k
Ω
0.5
1.0
0.01
±
1.0
0.5
20
0.15
vs. Temperature (Note 1) 0
°
C < T
A
< +70
°
C
vs. Supply Voltage
R3 = 1.5 k
Ω
for f
H
R3 = 2 M
Ω
for f
L
C = 5000 pF
f
H
= 10 kHz, f
L
= 1 kHz
f
H
= 100 kHz, f
L
= 100 Hz
±
10% FM Deviation
See Characteristic Curves
Measured at pins 4, 5, 6, or 7
1.5
1000:1 3000:1
1.0
5.0
0.1
2.0
%
%
%
2000
75
10
k
Ω
Ω
mV
V
P-P
Ω
mV
%
V
P-P
Measured at pin 14
Referenced to pin 10
from 10% to 90% of swing
Measured at pin 13,
S2 Closed
Referenced to pin 12
C
L
≤
10 pF
C
L
≤
10 pF
4
6
10
+100
0.1
11
12
0.2
200
20
0.4
V
ns
ns
4
PRODUCT SPECIFICATION
RC2207
Typical Performance Characteristics
+25
+20
Positive Supply (V)
+15
+10
+5
0
65-2207-03
,,,,,,,
,,,,,,,
,,,,,,,
,,,,,,,
,,,,,,,
,,,,,,,
,,,,,,,
,,,,,,,
,,,,,,,
,,,,,,,
Typical
Operating
Range
0
-5
-10
Negative Supply (V)
-15
7
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
-7
1K
Frequency Accuracy (% Error)
V
S
= +6V
C = 5000 pF
-20
10K
100K
Timing Resistance (Ω)
1M
10M
Figure 1. Typical Operating Range for
Split Supply Voltage
Figure 2. Frequency Accuracy vs. Timing Resistance
10M
Total Timing Resistor (Ω)
1M
100K
10K
1K
0
,,,,,,,,
,,,,,,,,
,,,,,,,,
,,,,,,,,
,,,,,,,,
,,,,,,,,
,,,,,,,,
,,,,,,,,
,,,,,,,,
,,,,,,,,
Timing
Resistor
Range
4
8
12
Split Supply Voltage (V)
0
8
16
24
Single Supply Voltage (V)
1.04
Normalized Frequency Drift
R
T
= 2 MΩ
1.02
1.00
0.98
0.96
0.94
0.92
2
4
6
8
65-2207-06
T
A
= +25°C
R
T
= 20 kΩ
R
T
= 200 kΩ
65-2207-05
T
A
= +20°C
R
T
= Total Timing Resistance
C = 5000 pF
R
T
= 2 kΩ
10
12
16
14
Split Supply Voltage (V)
32
4
8
12
14
18
Single Supply Voltage (V)
20
22
1
R = Parallel Combination of Activated Timing Resistors
T
Figure 3. Recommended Timing Resistor Value vs.
Power Supply Voltage
Figure 4. Normalized Frequency Drift vs.
Supply Voltage
+2
Normalized Frequency Drift (%)
+1
0
V
S
= +6V
C = 5000 pF
2 MΩ
200 kΩ
4 kΩ
2 kΩ
20 kΩ
-1 200 kΩ
-2
-3
-75
2 MΩ
2 kΩ
4 kΩ
R = 2 kΩ
65-2207-08
65-2207-07
-50
-25
0
+25
+50
+75
+100 +125
Temperature (°C)
Figure 5. Pulse and Sawtooth Outputs
Figure 6. Normalized Frequency Drift vs. Temperature
65-2207-04
5
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