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AM62D-Q1: Confusions about LPDDR4 Board Design and Layout Guidelines

Part Number: AM62D-Q1

Hi support,

We're doing LPDDR4 layout for AM62D. 

After reading this version of the DDR design guide https://www.ti.com/lit/an/sprad66b/sprad66b.pdf, I have several confusions.

1. According to LP4_DRS6 in Table 2-7, the propagation delay of DQSx can be greater than DQ/DM.

However, in 3.5.3.2, 'DQSx delays must be less than the DQ and DM delays in the respective BYTEx' is mentioned. Which design rules should be followed?

2. Besides, is LP4_ACRS3 in Table 2-6 too strict compared to LP4_DRS4 in Table 2-7?

The package delay between DDR0_CK0 and DDR0_CK0_N has exceeded the value LP4_ACRS3. So I want to double confirm.

3. According to LP4_DRS3 in Table 2-7, does CK delay must be greater than DQS? 

Thank you

Best regards

Wenjin

  • 您好,

    1.我认为建议一个字节内的DQS对应具有最短的延迟,但要求允许DQ/DM缩短50ps。 我同意这是一个有点混乱。 让我仔细检查一下,然后回复给您

    2.再次,让我再次检查这里。 绝对建议保持两个差分对(CK和DQS)的倾斜程度紧密匹配。 因此,应考虑包装+板的总长度。

    3.是的,CK延迟应大于DQS以方便写入水平算法。

  • hi, lydia

    还请确认1/2,这对我们很重要。

    谢谢

    Wenjin

  • Hi Wenjin,

    Please pay attention to your post in the English forum, our engineer JJD will help you

  • Hi Lydia

    OK, I will focus on another post. 

    Wenjin