1kHz – 68MHz Serial Port Programmable Oscillator

The LTC6903/LTC6904 are low power self contained digital frequency sources providing a precision frequency from 1kHz to 68MHz, set through a serial port. The LTC6903/ LTC6904 require no external components other than a power supply bypass capacitor, and they operate over a single wide supply range of 2.7V to 5.5V.

The LTC6903/LTC6904 feature a proprietary feedback loop that linearizes the relationship between digital control setting and frequency, resulting in a very simple frequency setting equation:

where OCT is a 4-bit digital code and DAC is a 10-bit digital code.

The LTC6903 is controlled by a convenient SPI compatible serial interface. The LTC6904 uses an industry standard I2C compatible interface.

Applications

* Precision Digitally Controlled Oscillator

* Power Management

* Direct Digital Frequency Synthesis (DDS) Replacement

* Replacement for DAC and VCO

* Switched Capacitor Filter Clock

* 1kHz to 68MHz Square Wave Output

* 0.5% (Typ) Initial Frequency Accuracy

* Frequency Error <1.1% Over All Settings

* 10ppm/°C Typical Frequency Drift Over Temperature

* 0.1% Resolution

* 1.7mA Typical Supply Current (f < 1MHz, VS = 2.7V)

* 2.7V to 5.5V Single Supply Operation

* Jitter <0.4% Typical 1kHz to 8MHz

* Easy to Use SPI (LTC6903) or I2C (LTC6904) Serial Interface

* Output Enable Pin

* –55°C to 125°C Operation

* MS8 Package