AM3517 DDR2 Series Termination

Prad

Other Parts Discussed in Thread: AM3517

Hi,

Does AM3517 DDR2 interface support two- resistor network (SSTL) type of Series Termination

mentioned in the apllication report(SLLA067B) Figure 15.

Please let me know what is the recomended design for AM3517's DDR2 series termination,and if there are any application note.

Thankyou and Regards.

over 16 years ago

0 Jeff Culverhouse over 16 years ago

TI__Genius 9190 points

Hello,

the AM3517 DDR2 interface does not support SST type series/parallel termination. Pure series termination is allowed if EMI is a consideration, but this is not necessary to meet signal integrity and overshoot requirements.

Please see section 6.4.3.1.9 of the AM3517/05 data manual for termination guidelines

For DDR2 routing and layout guidelines please also see the AM3517/05 data manual starting as section 6.4.2.

Best regards,
Jeff

0 Prad over 16 years ago in reply to Jeff Culverhouse

Expert 1125 points

Hello Jeff,

Thanks for the information.

Could you please let me know what is the reason behind "No terminations of any kind are required" in

case of AM3517, if I don't use any series resistor can I assume there won't be any noise issue.

Regards.

Prad

0 Jeff Culverhouse over 16 years ago in reply to Prad

TI__Genius 9190 points

Hello Prad,

With no terminations there could be an EMI noise issue. I was just saying that the device does not need the termination as it can still meet signal integrity and overshoot requirements...basically we would still be in spec with no termination.

I would think that you would need/want the series terminators to reduce EMI.

Best regards,
Jeff

0 Prad over 16 years ago in reply to Jeff Culverhouse

Expert 1125 points

Hi Jeff,

Thankyou.

The AM3517 datasheet states that the DDR2 Memory Controller supports

JESD79D-2A standard compliant but couldn't find the details about JESD79D-2A in JEDEC webpage.

And as you know AM3517(DDR2) I/O interfaces are LVCMOS type,

what is the merit of this type of interface when compared to SSTL type.

Thankyou.

0 Jeff Culverhouse over 16 years ago in reply to Prad

TI__Genius 9190 points

Hi Prad,

There is a type-o in the JEDEC number in the Data Manual...it should actually be JESD79-2A...the extra D after 79 should not be there!

Best regards,
Jeff

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AM3517 DDR2 Series Termination