P2597 B02 Schematic: HDMI Power Switch Current Limiter

Autonomous Machines Jetson & Embedded Systems Jetson TX1
1

I’m working on a custom board and adding support for HDMI. I’ve used the P2597 B02 Schematic as a reference (Thanks for this!) and I have a question about component U502 on page 14 location B1. Specifically about the IC :RT9728A Datasheet: [url]http://www.richtek.com/assets/product_file/RT9728A/DS9728A-06.pdf[/url]

The function of the fault pin is to pull the enable signal low when an overcurrent condition occurs. On this schematic the connection between the FAULT# and EN is tied together through a 0 ohm resistor.

The datasheet says (page 10):

“… The FAULT pin requires a pull-up resistor; this resistor should be large in value to reduce energy drain. A 100kΩ pull-up resistor works well for most applications. …”

It seems like the implementation is incorrect.

Am I not noticing something?

2

Hi cospan,

There will be a pull-up from net 5V0_HDMI_EN when chip is working as the chip EN is high enable, and so FAULT pin got its PU.

3

I was looking at an older version of the schematic B02, I just downloaded B04 and I see that resistors R548 and R549 are now 4.7K not 0Ohms.

Okay cool.