What is the DDR power specifications requirement for VTT and VTTREF

K. Sasaki14

Could you tell me about DDR power VTT and VTTREF requirement?

Are there DC and AC requirement? What level are those? Is there any ripple requirement or transient response requirement?

Best Regards,
Kohei Sasaki

over 6 years ago

0 Qian Chen over 6 years ago

TI__Mastermind 24075 points

Hi Kohei,

VTT current is to power DDR VTT terminnal. The VTT current is different on on different DIMM module. It is in several hundrend mA range.
VTTREF provides a reference voltage to DDR. The current is very small. For DDR3 and DDR4, the VTTREF current is only a few uA.

Thanks
Qian

0 K. Sasaki14 over 6 years ago in reply to Qian Chen

Guru 10200 points

Qian-san,

Thank you for your answer.
I would like to know about voltage range requirement. And also I would like to know voltage ripple and transient response requirement if there is any requirement.

Best Regards,
Kohei Sasaki

0 Qian Chen over 6 years ago in reply to K. Sasaki14

TI__Mastermind 24075 points

Kohei-san,

Different DDR type has different requirement on voltage range, ripple and transient.

I would suggest you to check JEDEC spec or DDR datasheet.

Thanks

Qian

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What is the DDR power specifications requirement for VTT and VTTREF