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TDA4VM: LPDDR4 LAYOUT design problems

JUNHONG CHEN
Prodigy 40 points
Part Number: TDA4VM

Hello, TI experts!

Currently, our PCB board uses 10 layers of through-holes for design, and we need your assistance when we encounter problems in LPDDR4.


The status is as follows:


Plan A: TDA4VMid 10 layer reference design, with Allegre software can be opened, but converted to PDAS 9.5 (suffix. PCB) was unsuccessful.


Plan B: TDA4VMid 16 layer board reference design, convert PADS 9.5 success. For LPDDR4 wiring, the design is compressed into 10 layers (wiring remains unchanged) and placed on layers L3, L5, L7, and L9.


Question1: For LPDDR4, the design of 10layer board is different from that of 16layer board (same impedance, different line width and line spacing). Currently, we plan to adopt "Plan B" to deal with it. Shall we use IBS model to simulate and then we can use it? Or must we refer to the design of the 10-layer board for Layout? Or do you have any suggestions?


Question 2:TDA4VMid SOC internal DDR cable length?

  • 0
    TI__Guru 52395 points

    Question 1:  Yes, IBIS model can be used for simulation and fine-tuning.  That is the expectation.  Use the TI designs for starting point or reference (either 10layer or 16layer), make the design changes required for your specific design, and then simulate to ensure design still meets requirements.  Again - both designs (10layer and 16layer) are considered working solutions.

    Question 2:  Below are the package delays for each LPDDR4 net (net, delay in ps)

    Net Delay (ps)
    DDR0_CA0 40.47
    DDR0_CA1 40.29
    DDR0_CA2 40.53
    DDR0_CA3 42.49
    DDR0_CA4 39.76
    DDR0_CA5 41.63
    DDR0_CAL0 42.71
    DDR0_CKE0 43.19
    DDR0_CKE1 39.94
    DDR0_CKN 42.68
    DDR0_CKP 43.66
    DDR0_CSN0_0 45.43
    DDR0_CSN0_1 39.29
    DDR0_CSN1_0 47.99
    DDR0_CSN1_1 40.56
    DDR0_DM0 61.84
    DDR0_DM1 51.93
    DDR0_DM2 34.79
    DDR0_DM3 31.10
    DDR0_DQ0 62.93
    DDR0_DQ1 62.45
    DDR0_DQ2 61.75
    DDR0_DQ3 62.30
    DDR0_DQ4 61.86
    DDR0_DQ5 62.56
    DDR0_DQ6 63.94
    DDR0_DQ7 63.32
    DDR0_DQ8 52.97
    DDR0_DQ9 52.55
    DDR0_DQ10 52.84
    DDR0_DQ11 52.90
    DDR0_DQ12 50.25
    DDR0_DQ13 51.93
    DDR0_DQ14 50.69
    DDR0_DQ15 50.39
    DDR0_DQ16 32.50
    DDR0_DQ17 32.72
    DDR0_DQ18 32.28
    DDR0_DQ19 31.99
    DDR0_DQ20 34.83
    DDR0_DQ21 32.23
    DDR0_DQ22 34.58
    DDR0_DQ23 32.83
    DDR0_DQ24 31.63
    DDR0_DQ25 31.21
    DDR0_DQ26 33.99
    DDR0_DQ27 31.74
    DDR0_DQ28 30.70
    DDR0_DQ29 30.73
    DDR0_DQ30 31.07
    DDR0_DQ31 31.33
    DDR0_DQS0N 62.59
    DDR0_DQS0P 61.50
    DDR0_DQS1N 50.94
    DDR0_DQS1P 51.44
    DDR0_DQS2N 33.35
    DDR0_DQS2P 34.17
    DDR0_DQS3N 33.33
    DDR0_DQS3P 32.35
    DDR0_RESETN 42.82