SY89424V

5V/3.3V FREQUENCY SYNTHESIZER (60MHz to 1GHz) FEATURES s 3.3V and 5V power supply options s Up to 1GHz clock frequencies s Internal quartz reference oscillator driven by quartz crystal or PECL source s Low jitter PLL design s On-chip 20 ohm driver s Differential outputs with 600mV (min) swing s Optional pull-down resistors for AC-coupled outputs s Low power consumption s External loop filter optimizes performance/cost s Available in 16-pin SOIC package ClockWorks™ SY89424V DESCRIPTION The SY89424V is a low-power Phase Locked Loop (PLL) based frequency synthesizer. The device is capable of generating up to 1GHz clock frequencies with a low-cost 10–25MHz external series-resonant quartz crystal. One can also use PECL differential clock signals to drive this device instead of the quartz crystal. Operation of this chip is controlled by three select pins (S1, S2 and S3). S1 selects the divide ratio of 24 or 50 for the PLL. S2 and S3 select the output frequency. There are two pull-down resistor pins (PDR1 and PDR2). Each pin has an on-chip resistor that will control the output driver currents. When PDR1 and PDR2 pins are open, both outputs are normal open emitter PECL drivers. When PDR1 and PDR 2 pins are shorted to the outputs, on-chip pull down currents of 25mA (40mA at 5V VCC) are provided. Both output drivers are capable of driving 20 ohm clock lines. An output enable (OE) pin is available and it can be HIGH or left open for normal operation. When OE is LOW, a built-in Disable...