AM623: Handling unused address pins

Agent_Orange

Prodigy 30 points

Part Number: AM623

Tool/software:

Hello,

We are using the AM623 and want to downsize from a 16Gbit memory to 8Gbit.

This is what the memory vendor says:

I'm trying to understand what to do with the unused DDR address pin.

I couldn't find the answer here:

https://www.ti.com/lit/ds/symlink/am623.pdf

6 months ago

0 JJD 6 months ago

TI__Guru* 85990 points

Please consult with the memory vendor to determine how to handle unused address signals on the DDR device. Unused address signals on AM623 can be left unconnected.

Regards,

James

0 Agent_Orange 6 months ago in reply to JJD

Prodigy 30 points

I posted the recommendation from the memory vendor. They suggest consulting the MPU vendor.

My current board (with 16GBits) has a resistor connected to the address pin that will be unused in the new memory (8Gbts). I don't want to make changes to the board. Can I live that resistor connected ?

0 JJD 6 months ago in reply to Agent_Orange

TI__Guru* 85990 points

What is the other pin of the resistor connected to? Can you show me a schematic?

Regards,

James

0 Agent_Orange 6 months ago in reply to JJD

Prodigy 30 points

0 JJD 6 months ago in reply to Agent_Orange

TI__Guru* 85990 points

i don't see a resistor on any address signal. At any rate, the portion of the schematic you posted looks ok.

Regards,

James

0 Agent_Orange 6 months ago in reply to JJD

Prodigy 30 points

Sorry. It was my mistake. There's no resistor.

So the 16Gbits memory can be replaced with the 8Gbits part without any changes to the board ?

+1 JJD 6 months ago in reply to Agent_Orange

TI__Guru* 85990 points

I believe it should be fine. The extra address signal just won't be used. This is typical so that customers can exchange different density devices with the same footprint.

Regards,

James

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AM623: Handling unused address pins