RE: Custom PCB - nRF52840 VDDH and USB

Jared — Tue, 18 Jun 2019 10:43:46 GMT

Yes!

RE: Custom PCB - nRF52840 VDDH and USB

Matthew K — Mon, 17 Jun 2019 13:09:04 GMT

[quote userid="73165" url="~/f/nordic-q-a/48444/custom-pcb---nrf52840-vddh-and-usb/193166"]We don't have any guidelines except our advice on following the reference design as close as possible. [/quote]

Thanks, Jared. Meaning keep a large keep out area for D+, D-?

RE: Custom PCB - nRF52840 VDDH and USB

Jared — Mon, 17 Jun 2019 12:09:30 GMT

Hi,

For my USB application, can I connect the buck converter's output (3.3V) to both VDDH(Y2) and VDD(W1) for using the Normal voltage mode (pin VDD shorted to pin VDDH)? Also, if I connect both VDDH and VDD to 3.3V, I can only use DC/DC converter which can be enabled by REG1, right? If I add the external LC filters, configure the registers for the internal DC/DC regulators, and connect the Li-ion's 3.7V or USB 5V to VDDH, does this mean that I can remove an external buck converter? This looks like if I connect the 3.7V Li-ion to the VDDH, I don't need to provide an external 3.3V, right?
- VDD and VDDH should be connected together in normal mode. 3.3 V is within the operating range of normal mode. Yes, only REG1 is available in normal mode. Yes, the buck converter is not necessary for the IC to function. See the reference design on what parts that are necessary.
What does the red pulse, next to D* N and D* P, mean?
- It means that the data lines D negative and D positive will change values ( 0, 1) and not be a steady value.
The USB D+, D- trace I noticed the thin line and removed copper. Are there any guidelines for drawing USB connection (D+, D- trace width/length, keep out area, etc)?
- We don't have any guidelines except our advice on following the reference design as close as possible.

Regards

Jared