CDCS503: Spread-Spectrum Clocking recommend for 37.125MHz

Bonnie Chen

Intellectual 1140 points

Part Number: CDCS503
Other Parts Discussed in Thread: CDCE913, , CDCS501

SSC used at Sensor Clock 37.125MHz,

Input 37.125MHz, Output 37.125MHz + 1% SSC

can you help to recommend suitable Spread-Spectrum Clocking recommend?

501 and 503 freq not fit this application.

what will happened if customer use Input 37.125MHz to 503?

over 6 years ago

0 Puneet Sareen over 6 years ago

TI__Expert 8865 points

Hello Bonnie
We have possibility to generate either down spread or center spread. You can use CDCE913 instead of CDCS503. It is a similar device with extended input frequency range.
If 37.125MHz is used with CDCS503, VCO for the PLL will be out of range. It might work if one unit is tested but over process and VT, it might fail.
Best regards
Puneet

0 Bonnie Chen over 6 years ago in reply to Puneet Sareen

TI__Intellectual 1140 points

Hi Puneet,

customer cant not use outside OSC or crystal. and they also prefer one output solution(smaller)

Can you help to recommend part?

SOC output 3.3V 37.125MHz => SSC 3.3V 37.125MHz 1% (CDCS501/3) => SN74AVC1T45DRLR 3.3V -> 1.8V => Sensor 1.8V 37.125MHz

0 Puneet Sareen over 6 years ago in reply to Bonnie Chen

TI__Expert 8865 points

Hi Bonnie
CDCE913 has also LVCMOS input.
By the way, CDCS501 should also work although the min frequency for this device is 40MHz, but 37.125MHz should also work. With CDCS503, the max frequency is 32MHz and using 37MHz as input, VCO will have to run at higher frequency which might be an issue. Running the VCO little bit lower frequency should be fine.
Best regards
Puneet

0 Bonnie Chen over 6 years ago in reply to Puneet Sareen

TI__Intellectual 1140 points

Hi Puneet,

I don't feel it's good to recommend out of spec design like 501. we can't guarantee the mass production quality.

0 Puneet Sareen over 6 years ago in reply to Bonnie Chen

TI__Expert 8865 points

Hi Bonnie,
I would recommend to use CDCE913. It is 3 output device but very flexible. There is also onchip EEPROM, so no in-system programming needed. Like I said, there is no need to use Xtal as the device supports LVCMOS.
Best regards
Puneet

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CDCS503: Spread-Spectrum Clocking recommend for 37.125MHz