February 2, 2007 AT 8:51 pm

CotW – LTC6903

For an upcoming project I need a variable clock source: up to 50MHz and as low as 10KHz. So I looked up VXCOs, PLLs, DDSs, etc etc. all not quite what I wanted.
And then I found this, the LTC6903, 1KHz-68MHz SPI (or I2C) programmable oscillator, 8 pins,

Check out this kinky "typical app"

As Javaman says, “its like a monk that can control his own heartrate”

Congrats LTC690x, you are the Chip of the Week!

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2 Comments

  1. What for code (Bascom or basic) would I need to run this dude? I’m building a pc board right now to run this oscillator with a Mega48 AVR.

  2. Hi

    Well I tried and failed with this using different parts………..any suggestions are very welcome

    // Arduino using DDS60/AD9851 with 30MHz Osc clock ~ Bare Bones Test 16
    // For AD9851 array values see http://www.analog.com/Analog_Root/static/techSupport/designTools/interactiveTools/dds/ad9851.html
    // For AD9851 datasheet see http://www.analog.com/en/prod/0%2C2877%2CAD9851%2C00.html
    // For DDS60 see http://www.amqrp.org/kits/dds60/index.html
    // For Arduino see http://www.arduino.cc/en/Guide/HomePage
    // by Mike Bowthorpe

    byte DATA = 10; //DATA on pin 10/3
    byte CLOCK = 9; //CLOCK on pin 9/2
    byte LOAD = 8; //LOAD on pin 8/1
    byte pin13 = 13;

    void setup()
    {
    pinMode (DATA, OUTPUT); // sets pin 10 as OUPUT
    pinMode (CLOCK, OUTPUT); // sets pin 9 as OUTPUT
    pinMode (LOAD, OUTPUT); // sets pin 8 as OUTPUT
    pinMode (pin13, OUTPUT);
    }

    void loop()
    {
    {

    shiftOut(DATA,CLOCK,LSBFIRST,(0,119,250,137,230)); // 5 values W0, W1, W2, W3, W4 to give 14.06000 MHz with 30MHz Osc

    digitalWrite (LOAD, HIGH); // Turn on pin 8/1 LOAD FQ-UD
    digitalWrite (LOAD, LOW); // Turn pin 8 off

    }
    }

    Regards

    Mike

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