ADC12DJ3200: DDC line rate calculation

Patrick Zat

Prodigy 30 points

Part Number: ADC12DJ3200

Hi @ all,

I'm currently a bit confused about the JESD line rate, specifically the way of calculation, could you please clarify.

My understanding, so far:

Linerate = Fclk x R

by Using JMODE 0, clk 800MHz

Linerate = 800MHz x 4 = 3,2Gbps

In JMODE0 single channel operation is applied, thus sample rate is 1600Gbps, nethertheless for calculation of line rate 800Mhz is used, is this correct?

by using JMODE 10, DDC=4, clk 800MHz

800Mbps/4 = 200Mbps (after DDC)

for line rate calculation:

linerate = 200Mbps x 5 = 1Gbps?

linerate= 800Mbps x 5= 4Gbps?

The same for SYSREF calculation:

My understanding was that only Fclk needs to be considered not the Frequency after DDC, ?

over 2 years ago

+1 Neeraj Gill over 2 years ago

TI__Mastermind 20541 points

As you mentioned the lane rate = Linerate = Fclk x R. For JMODE10, R = 5 and with Fclk = 800MHz, Linerate = 800MHz X 5 = 4Gbps.

Sysref Freq = LaneRate/(K x F x 10 x N) where N is positive integer . We will pick K = 10 and F = 2, N = 1

Sysref Freq = 4Gbps/(10 x 2 x10 x 1) = 20MHz.

Regards,

Neeraj

+1 Patrick Zat over 2 years ago in reply to Neeraj Gill

Prodigy 30 points

Hi Neeraj

thank you for your fast response.

for Sysref Freq, I thought it is limited to max. 10Mhz ?

+1 Neeraj Gill over 2 years ago in reply to Patrick Zat

TI__Mastermind 20541 points

Neeraj Gill said:
Sysref Freq = LaneRate/(K x F x 10 x N) where N is positive integer . We will pick K = 10 and F = 2, N = 1

Sysref Freq = 4Gbps/(10 x 2 x10 x 1) = 20MHz.

The Max Sysref freq is 20MHz in above use case. if you pick different value for K say 20 then the max sysref will be 10MHz.

Regards,

Neeraj

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ADC12DJ3200: DDC line rate calculation