RC2207

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 –VS 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 +VS 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 +VS 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 +VS/3 and +VS/2 (see Figure 8). The bias current at pin 11 is nominally 5% of the total oscillation timing current IT. The internal impedance at these pins is approximately 5 kΩ. Keying levels are 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 µF bypass capacitor. During split supply operation, a ground current of 2 IT flows out of this terminal, where IT 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. RL serves as a pull-up load resistor for this output. Recommended values for RL range from 1 kΩ to 10 kΩ 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 µF. The capacitor should be non-polarized. The timing resistors determine the total timing current, IT, available to charge the timing capacitor. Values for timing resistors can range from 1.5 kΩ to 2 MΩ; however, for optimum temperature and power supply stability, recommended values are 4 kΩ to 200 kΩ. 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 µF 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 10Ω 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 (+VS, –VS) 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 PD TA < 50°C Thermal Resistance, θJC Thermal Resistance, θJA For TA > 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 Electrical Characteristics Parameters General Characteristics Supply Voltage Single Supply Split Supplies Supply Current Single Supply Split Supplies (Test Circuit of Figure 1, VS = ± 6V, TA = +25°C, C = 5000 pF, R1= R2 = R3 = R4 = 20 kΩ, RL = 4.7Ω binary inputs grounded, S1 and S2 closed unless otherwise specified) Test Conditions See Typical Performance Characteristics Measured at pin 1, S1 open (See Fig. 8) 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 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. 1 Min. +8.0 ±4 Typ. +12 ±6 5.0 Max. +26 ± 13 7.0 7.0 8.0 7.0 Units V V mA mA mA Measured at pin 1, S1 open (See Fig. 7) Measured at pin 12, S1, S2 open RC2207 RM2207 RC2207 RM2207 1.4 5.0 4.0 2.2 5.0 6.0 2.8 V kΩ MHz Hz ± 3.0 % of f0 % of f0 50 ppm/°C %/V fH/fL Measured at pins 8 and 9. Refer to pin 10. C = 500 pF, R3 = 2 kΩ C = 50 µF, R3 = 2 kΩ 0.5 1.0 0.01 ± 1.0 0.5 20 0.15 vs. Temperature (Note 1) 0°C < TA < +70°C vs. Supply Voltage R3 = 1.5 kΩ for fH R3 = 2 MΩ for fL C = 5000 pF fH = 10 kHz, fL = 1 kHz fH = 100 kHz, fL = 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 % % % 1000:1 Sweep 2000 75 10 kΩ Ω mV VP-P Ω mV % VP-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 CL ≤ 10 pF CL ≤ 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) VS = +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 TA = +25°C RT = 20 kΩ RT = 200 kΩ 65-2207-05 TA = +20°C RT = Total Timing Resistance C = 5000 pF RT = 2 kΩ 10 12 16 14 Split Supply Voltage (V) 32 4 8 12 14 18 Single Supply Voltage (V) 20 22 1R = 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 VS = +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 RC2207 PRODUCT SPECIFICATION Applications Information Precautions The following precautions should be observed when operating the RC2207 family of integrated circuits: • Pulling excessive current from the timing terminals will adversely affect the temperature stability of the circuit. To minimize this disturbance, it is recommended that the total current drawn from pins 4, 5, 6 and 7 be limited to