AM4376: DDR3 schematic questions

yimin bai34

Genius 4755 points

Part Number: AM4376

Hi SIr

we used AM4376 for development an there are some questions as below

1. The AM437x GP EVM has a 1K pull up to VDDS_DDR on the DDR_RESETn signal but the AM437x IDK/Starterkit does NOT have.

Which one is the correct setting? what condition to add 1K pull up ?

2.After testing, we found that we need DDR_CKE to add pull up resistor to VDDR_VTT, Otherwise, it will cause system hang. what is the risk if we add pull up resistor?

PS: IDK: DDR_CKE add 47 pull-up resistor to VDDR_VTT and GP-EVM: DDR_CKE remove 47 pull-up resistor to VDDR_VTT

Yimin

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Please follow this guide: processors.wiki.ti.com/.../AM437x_Schematic_Checklist

0 yimin bai34 over 7 years ago in reply to Biser Gatchev-XID

Genius 4755 points

Hi Sir

we have checked below link, please offer suggestion for my question.
processors.wiki.ti.com/.../AM437x_Schematic_Checklist

0 Biser Gatchev-XID over 7 years ago in reply to yimin bai34

TI__Guru**** 393215 points

No, DDR_CKE must NOT be terminated to Vtt. If necessary, you can add a 4.7kOhm pulldown to GND on this line. Same is true for the DDR_RESET pullup - it's not mandatory, but can be placed if necessary.

0 yimin bai34 over 7 years ago in reply to Biser Gatchev-XID

Genius 4755 points

Hi Sir

thanks for your reply.

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AM4376: DDR3 schematic questions