AS3340 : Voltage Controlled Oscillator (VCO)Features:Large Sweep Range: 500,000:1Fully Temperature CompensatedFour Output Waveforms Available; No waveform trimming requiredSumming Node Inputs for Frequency ControlHigh Exponential Scale AccuracyLow Temperature DriftVoltage Controlled Pulse WidthHard and Soft Sync InputsLinear FMBuffered, Short Circuit Protected Outputs±15 Volt SuppliesGeneral Description:The AS 3340 and AS 3345 are completely self contained, precision voltage controlled oscillators, featuring both exponential and linear control scales and up to four buffered output waveforms: triangle, sawtooth, square, and pulse with voltage controllable pulse width. Full temperature compensation makes these VCOs extremely stable, and eliminates the need for a temperature compensation resistor. The highly accurate exponential and linear control inputs are virtual ground summing nodes, allowing multiple control voltages to be mixed within the device itself.Also included is provision for hard and soft synchronization of the frequency, and an output for easy adjustment of high frequency tracking. Special care in the design ensures oscillation start-up under any power-on sequence and supply conditions. An on-chip 7.4 volt Zener diode allows the device to operate off ±15 volt supplies, as well as +12, -5 volt supplies. For voltages greater than -7.5 volts, a series current limiting resistor REE must be added between pin 3 and the negative supply. Its value is calculated as follows: REE = (VEE - 7.4) / .008To minimize self-heating and improve thermo-stability it is recommended to keep VEE = -5V (external power supply).Power pad in QFN package highly improves thermal stability of parameters of AS3345F. External VEE also minimize current through GND and improves VCO stability. Scale1 and Scale2 pins are used for trimming of thermo-compensation circuit. Resistor RZ, connected to Scale 1 pin, should provide the same current as current (approx.. 100 uA) flowing in Scale2 pin determined by resistor RT = 5.72k.Rs , resistor connected to pin Scale, is intended to trim V/oct range. AS3340A/AS3345A are improved versions of AS3340/AS3345. AS3340A/AS3345A and have much more output frequency stability against Vcc and VEE . Frequency stability can be improved If external reference voltage (with level approximately 1/3 Vcc) is connected to pin 9 (Soft Sync. Input).AS3340A/AS3345A benefits from improved symmetry of rising and falling edge of triangle signal (approx.. 50%).AS3345/AS3345A benefits from additional Meander Output. Meander edge starts when Triangle changes it’s direction.These feature gives additional opportunities for design.