DS1085L

The DS1085L is a dual-output frequency synthesizer requiring no external timing components for operation. It can be used as a standalone oscillator or as a dynamically programmed, processor-controlled peripheral device. An internal master oscillator can be programmed from 33MHz to 66MHz with three resolution options of 5kHz, 12.5kHz, and 25kHz. 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 4.13MHz to 66MHz. A second independent prescaler and a 1-to-1025 divider allow the generation of a main oscillator output (OUT1) from 4.1kHz to 66MHz. 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 DS1085L 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 can also be configured to disable the master oscillator, putting the device into a low-power mode for power-sensitive applications.

Applications

• Cable Modems
• Cell Phones
• Computer Peripherals
• Copiers
• PCs
• Printers