TFP410: Termination registers of TFP410-Reference schematics

Tatsuhiko Narioka

Part Number: TFP410

Tool/software:

Hi,
I have two questions regarding the TFP410 Reference schematics.

Q1) In the reference circuit of the TFP410, 1kΩ pull-down resistors are included for the T.M.D.S signals.
However, there is no mention in the datasheet (and guidlines) about these resistors.
　　Which documents are recommended?

Q2) If there are no resistors, what kind of impact can be expected?
(ex how does it affect display detection on the transceiver side?)

over 1 year ago

0 Vishesh Pithadiya over 1 year ago

TI__Mastermind 40460 points

Hey,

Can you send the link for the reference schematic with the 1k p-down option? I cant find that document.

+1 Vishesh Pithadiya over 1 year ago in reply to Vishesh Pithadiya

TI__Mastermind 40460 points

Tatsuhiko Narioka said:
In the reference circuit of the TFP410, 1kΩ pull-down resistors are included for the T.M.D.S signals.
However, there is no mention in the datasheet (and guidlines) about these resistors.
　　Which documents are recommended?

The reasoning behind these pulldowns is so there are no High-Z/ floating nodes when a HDMI cable is not connected. When a cable is plugged in there will be a 50Ohm resistor pulling the lanes up to 3.3V and as 50 Ohm pullup is a stronger pull up than a 1k pulldown. The common mode voltage when a cable is plugged in will still be approx. 3.3V.

Tatsuhiko Narioka said:
f there are no resistors, what kind of impact can be expected?

If these resistors are not populated there will be no impact on functional performance.

Interface

Interface forum

TFP410: Termination registers of TFP410-Reference schematics