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
RAYTHEON [ RAYTHEON COMPANY ]
