DS1085Z-10+

DS1085 EconOscillator Frequency Synthesizer www.maxim-ic.com FEATURES PIN ASSIGNMENT User-Programmable Frequency Synthesizer 1 8 OUT1 SCL Programmable From 8.1kHz to 133MHz 2 7 OUT0 SDA Dual Synchronous Outputs 3 6 8.2MHz to 133MHz Reference Oscillator V CTRL1 CC Output 4 5 GND CTRL0 8.1kHz to 133MHz Main Oscillator Output SO (150mil) Three Resolution Options 2-Wire Serial Interface 0.75% Absolute Accuracy Nonvolatile (NV) Frequency Settings Single 5V Supply PIN DESCRIPTION No External Timing Components OUT1 - Main Oscillator Output Power-Down Mode OUT0 - Reference Oscillator Output V - Power-Supply Voltage CC GND - Ground CTRL1 - Control Pin for OUT1 CTRL0 - Control Pin for OUT0 SDA - 2-Wire Serial Data Input/Output SCL - 2-Wire Serial Clock ORDERING INFORMATION STEP OSCILLATOR DEVICE PACKAGE SIZE OUTPUT RANGE DS1085Z-10 150mil SO 10kHz 8.1kHz to 133MHz DS1085Z-25 150mil SO 25kHz 8.1kHz to 133MHz DS1085Z-50 150mil SO 50kHz 8.1kHz to 133MHz DESCRIPTION The DS1085 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 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. EconOscillator is a trademark of Dallas Semiconductor. 1 of 21 051506 DS1085 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. Figure 1. DS1085 BLOCK DIAGRAM 0M0 0M1 1M0 1M1 OVERVIEW A block diagram of the DS1085 is shown in Figure 1. The DS1085 consists of five major components: Master oscillator control DAC Internal master oscillator (66MHz to 133MHz) Prescalers (divide-by-1, 2, 4, or 8) Programmable divider (divide-by-1 to 1025) Control registers The internal master oscillator provides the reference clock (MCLK), which is fed to the prescalers and programmable dividers. The frequency of the oscillator can be user-programmed over a two-to-one range in increments equal to the step size, by means of a 10-bit control DAC. The master oscillator range is 66MHz to 133MHz, which is larger than the range possible with the 10-bit DAC resolution and available step sizes. Therefore, an additional register (OFFSET) is provided that can be used to select the range of frequency over which the DAC is used (see Table 1). 2 of 21