DS1085LZ-5+

DS1085L 3.3V EconOscillator Frequency Synthesizer www.maxim-ic.com FEATURES OUT1 1 8 SCL User-Programmable Frequency Synthesizer A OUT0 2 7 SD Programmable From 4.1kHz to 66MHz Dual Synchronous Outputs V CTRL1 CC 3 6 4.13MHz to 66MHz Reference Oscillator 4 5 GND CTRL0 Output SO (150mil) 4.1kHz to 66MHz Main Oscillator Output Single 3.0 to 3.6V Supply Three Resolution Options PIN DESCRIPTION 2-Wire Serial Interface OUT1 - Main Oscillator Output 0.75% Absolute Accuracy OUT0 - Reference Oscillator Output Nonvolatile (NV) Frequency Settings V - Power-Supply Voltage CC No External Timing Components GND - Ground Power-Down Mode CTRL1 - Control Pin for OUT1 CTRL0 - Control Pin for OUT0 SDA - 2-Wire Serial Data Input/Output ORDERING INFORMATION SCL - 2-Wire Serial Clock PIN ASSIGNMENT STEP OSCILLATOR DEVICE PACKAGE SIZE OUTPUT RANGE DS1085LZ-5 150mil SO 5kHz 4.1kHz to 66MHz DS1085LZ-12 150mil SO 12.5kHz 4.1kHz to 66MHz DS1085LZ-25 150mil SO 25kHz 4.1kHz to 66MHz DESCRIPTION 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. EconOscillator is a trademark of Dallas Semiconductor. 1 of 21 051606 DS1085L 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. Figure 1. DS1085L BLOCK DIAGRAM 0M0 0M1 1M0 1M1 OVERVIEW A block diagram of the DS1085L is shown in Figure 1. The DS1085L consists of five major components: Internal master oscillator (33MHz to 66MHz) Master oscillator control DAC 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 33MHz to 66MHz, 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