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Is VTT - DDR3 terminal circuit required?

Dat Tran
Senior II

Hi, according to "AN5256 Application note", I think VTT -DDR termination resistors circuitry is ok to be removed.

0693W00000WLDjxQAH.png 

Does it mean all things relate to VTT DDR below are also safe to remove out of the design?

0693W00000WLDk7QAH.png 

Many thanks

1 REPLY 1
PatrickF
ST Employee

Hi @Community member​ 

I confirm that when using x16 DDR3L, the termination resistors (and so the associated VTT supply) are optional.

Please also refer to AN5031, AN5122 and AN5168 as well using CubeMx generated configuration.

We have seen that DDR3L timings are quite robust and usually works without any headache (if routing is following AN5122 and/or provided examples as much as possible) .

DDR3L (1.35V) has to be prefered to DDR3 (1.5V) as lower voltage swing and lower power is better for signal integrity.

Regards.

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