crystal controlled, settable frequency

David Nyce

Other Parts Discussed in Thread: CDCE913, CDCEL913-Q1, CDCE913-Q1

I have been looking through the parametric searches. I'm not sure what category the part I want would be. It might be called a clock generator, or a direct digital synthesizer, or a frequency generator, or a function generator, etc. I dont know the best category to call it. But I'm looking for an IC that would produce a square wave output at a selected integer frequency from 8 kHz to 160 kHz, with my micro controller being able to select the frequency. It should be crystal-controlled so that the selected frequency is accurate.

over 10 years ago

0 Arvind Sridhar over 10 years ago

TI__Mastermind 24205 points

Hi David,

Please take a look at the CDCE913 datasheet (link below) to see if this device will fit your needs.

http://www.ti.com/product/cdce913

Regards

Arvind Sridhar

0 David Nyce over 10 years ago in reply to Arvind Sridhar

Prodigy 200 points

Thanks. I forgot to mention that it needs to have an operating temp of -40 to 125C. The CDCE913 datasheet will take me a while to digest. With an 8MHz crystal, for example, will my microcontroller be able to set output 1 equal to any frequency from 80kHz to 160kHz during normal operation? Can output 2 be set at the same time to equal the frequency of output 1 divided by 100?

0 David Nyce over 10 years ago in reply to David Nyce

Prodigy 200 points

I meant 8 kHz to 160 kHz.

0 Arvind Sridhar over 10 years ago in reply to David Nyce

TI__Mastermind 24205 points

Hi David,

Take a look at CDCE913-Q1 or CDCEL913-Q1. These devices are automotive grade and have a wide temperature range of operation (-40C to 125C). The minimum VCO frequency is 80 MHz. There is a 10-bit output divider so the min output frequency is ~78 kHz.

Regards

Arvind Sridhar

0 David Nyce over 10 years ago in reply to Arvind Sridhar

Prodigy 200 points

Sounds like it might be OK, but I don't understand why you said the minimum VCO is 80MHz. For example, with an 8MHz crystal, how do I set the controls so the output is 8 kHz? Thanks.

0 Arvind Sridhar over 10 years ago in reply to David Nyce

TI__Mastermind 24205 points

Hi David,

8 kHz is not achievable. With an 80 MHz VCO (min VCO frequency) and max output divider (1023), the min output frequency is limited to ~78 kHz. See example case below for 80 kHz synthesis from a 8 MHz Crystal.

0 David Nyce over 10 years ago in reply to Arvind Sridhar

Prodigy 200 points

Then that means it can't handle the application, because it needs to generate 8kHz to 160kHz.

Clock & timing

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crystal controlled, settable frequency