DS1085

The DS1085 is a dual-output frequency synthesizer requiring no external timing components for
operation. DS1085 can be used as a standalone oscillator or as a dynamically programmed, processor-controlled
peripheral device. An internal master oscillator can be programmed from 66MHz to 133MHz with three
resolution options of 10kHz, 25kHz, and 50kHz. A programmable, 3-bit prescaler (divide-by-1, 2, 4, or 8) permits the generation of a reference oscillator output (OUT0) from the master, ranging from 8.2MHz to 133MHz. A second independent prescaler and a 1-to-1025 divider allows the generation of a main oscillator output (OUT1) from 8.1kHz to 133MHz. The two outputs, although synchronous with the master, can be independently programmed. The combination of programmable master oscillator, prescalers, and dividers allows the generation of thousands of user-specified frequencies. All master oscillator, prescaler, and divider settings are stored in NV (EEPROM) memory, providing a default value on power-up that allows it to be used as a standalone oscillator. A 2-wire serial interface allows in-circuit, on-the-fly programming of the master oscillator, prescalers (P0 and P1), and divider (N). This allows dynamic frequency modification, if required, or, for fixed-frequency applications, the DS1085 can be used with factory- or user-programmed values.

External control inputs, CTRL1 and CTRL0, enable or disable the two oscillator outputs. Both outputs feature a synchronous enable that ensures no output glitches when the output is enabled and a constant time interval (for a given frequency setting) from an enable signal to the first output transition. These inputs also can be configured to disable the master oscillator, putting the device into a low-power mode for power-sensitive applications.