TDA4VEN-Q1: PCB Constraint

Furuna Yamamoto

Part Number: TDA4VEN-Q1
Other Parts Discussed in Thread: AM62P

Tool/software:

We are checking the high-speed interface design guidelines "spracp4a.pdf" to understand the PCB design constraint of the following IF.

1). OLDI(LVDS) IF

2). OSPI IF

3). eMMC IF

I don't see the above IF constraint in the guidelines, but is there no design constraint itself?

Or is it listed in another document?

Best regards,

4 months ago

0 Robert Eschler 4 months ago

TI__Guru 52245 points

For OLD, please refer to other E2E post on this topic:

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1329009/am625-oldi-interface-impedance

For OSPI, eMMC - don't have any specific guidelines. Recommend routing traces at 50-ohms SE and minimizing trace length as much as possible.

0 Furuna Yamamoto 4 months ago in reply to Robert Eschler

Prodigy 250 points

Hi Robert

Thank you for your answer.

[For OLDI]

I understood following point.

- There are 2-mode in OLDI(slow mode and fast mode).

- Customer can set "RTERM_EN = 1b" or "RTERM_EN = 0b" in fast mode.

Please tell us about the following.

- if reciever ic have termination resistor, is there no need for a terminator on the PCB near the receiver IC?

- Is correct that if signal quality can be ensured, the built-in terminating resistor of TDA4VEN is unnecessary (RTERM_EN = 0b) even in fast mode?

- Is the trace impedance 100ohm?

- For TDA4VEN, which document contains instructions for setting up OLDI?

0 ShreyasRao 4 months ago in reply to Furuna Yamamoto

TI__Guru 62140 points

Yes, If the receiver has termination resistor, then you do not need another term resistor to have double termination.

It seems that the Rterm is hidden register; im not sure why.

you could set the 0x108600 (for OLDI_DAT0) to 0x1083009. It enables Rterm and also increases the transmitter drive current from 3.2mA to 6.4mA.

0 ShreyasRao 4 months ago in reply to ShreyasRao

TI__Guru 62140 points

By default, the Rterm is disabled and should read 0Xxx3008h.

Similarly, for the CLK_ctrl register, it would be 0x8610h offset.

0 Furuna Yamamoto 4 months ago in reply to ShreyasRao

Prodigy 250 points

Thank you for your answer.

On our product, the trace of TDA4VEN to receiver IC is PCB pattern only (there is no W/H).

Therefor, I think that the double termination is not need(active termination is on die receiver termination only).

0 Furuna Yamamoto 4 months ago in reply to Furuna Yamamoto

Prodigy 250 points

Please also answer the following two questions.

- Is the trace impedance 100ohm?

- For TDA4VEN, which document contains instructions for setting up OLDI?

0 Robert Eschler 4 months ago in reply to Furuna Yamamoto

TI__Guru 52245 points

Yes - trace impedance is 100-ohms differential. The TRM (Technical Reference Manual) is the programmers manual for the processor.

0 Furuna Yamamoto 4 months ago in reply to Robert Eschler

Prodigy 250 points

Can you give me a link to the TRM?

0 Robert Eschler 4 months ago in reply to Furuna Yamamoto

TI__Guru 52245 points

All documents should be available on TI.com:

TDA4AEN TRM: Link

If information is missing, try also the AM62P TRM Link. Both processors should have similar OLDI programming.

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TDA4VEN-Q1: PCB Constraint