Rainbow-electronics DS1094L Uživatelský manuál stáhnout pdf (Strana 6)

DS1094L

Detailed Description

The DS1094L consists of a master oscillator, prescaler,

phase generator, and triangle-wave generator (used to

dither the master oscillator), which are all programma-

ble using the 2-wire interface and stored in NV memory.

Master Oscillator

The master oscillator is responsible for generating the

timing (frequency) of the outputs. The master oscillator

frequency, f

MOSC

, can be programmed anywhere

between 1MHz to 2MHz in 100kHz steps. The master

oscillator is programmed using the DAC register. The four

MSBs of the DAC register are don’t cares, while the four

LSBs (D3 to D0) are the DAC value. The master oscillator

frequency is determined using the following equation:

MOSC

= 1MHz + (DAC value x 100kHz)

Valid values for DAC are 0 to 10 (dec). DAC values

greater than 10 exceed the 2MHz limit and are not per-

mitted.

The master oscillator also determines the spread-spec-

trum dither frequency. This is described in the Triangle

Wave Generator section.

Multiphase Spread-Spectrum EconOscillator

6 _____________________________________________________________________

GND

MASTER

OSCILLATOR

1MHz TO 2MHz

PRESCALER

DIVIDE BY

1, 2, 4, OR 8

TRIANGLE

WAVE

GENERATOR

2-WIRE

SERIAL

INTERFACE

TWO/THREE/

FOUR-PHASE

GENERATOR

DAC

PRESCALER

ADDR

D0D1D2D3XXXX

P0P1J0J1PH0PH1D0D1

A0A1A2WCXXXX

SCL

SDA

DITHER RATE

DITHER %

EEPROM

WRITE EE

COMMAND

OUT2

OUT1

OUT3

OUT4

2-WIRE ADDRESS BITS

PHASE SELECTPRESCALER SETTING

EEPROM WRITE CONTROL

CONTROL REGISTERS

DAC SETTING

MOSC

OSC

MOSC

MOD

OUT

DS1094L

Functional Diagram

DAC VALUE (dec)

DAC REGISTER

MOSC

0 00h 1.0MHz

1 01h 1.1MHz

2 02h 1.2MHz

———

10 0Ah 2.0MHz

11 to 15 0Bh to 0Fh Reserved

Table 1. Master Oscillator Settings

BITS P1, P0 DIVISOR f

OSC

00 2

MOSC

01 2

MOSC

10 2

MOSC

11 2

MOSC

Table 2. Prescaler Settings

1 2 3 4 5 6 7 8 9 10 11

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