CC3301: Why does CC3301 layout need 5 mils for SDIO trace width?

Jesse Wang

Part Number: CC3301

Hi TI expert,

According to TI application note, "CC33xx Hardware Integration User's Guide (Rev. A) ", the SDIO needs at least 5 mils trace width.

Why is it?

If we run the simulation for 50 ohm impedance, it seems the best trace width is ~4.3 mil.

BR, Jesse.

4 months ago

0 Dylan Hubbard 4 months ago

TI__Mastermind 48155 points

Hey Jesse,

This isn't a hard requirement and mostly just for engineers who aren't experts in digital/highspeed layout design. If gives them a safe value that is typically standard to manufacture. Also note: having a 50ohm Zo is not very critical with digital communication.

0 Ray Chang 4 months ago

Prodigy 20 points

Hi Dylan,
If the 50-ohm impedance requirement results in a trace width of 4 or even 3 mils, would you still recommend a 5-mil width for SDIO traces ?

0 Dylan Hubbard 4 months ago in reply to Ray Chang

TI__Mastermind 48155 points

Hey Ray,

As I stated at the end of my last post - 50ohms trace is not critical for digital traces. If there are no issues on the PCB manufacturing, then feel free to make them 3-4 mils.

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CC3301: Why does CC3301 layout need 5 mils for SDIO trace width?