Help with a Skywire/Airgain modem on a custom PCB

Projects General Guidance
1

Hi!

I am trying to embed a Skywire Airgain modem to my custom PCB, but it is not working out so well.

Here is my schematic:

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Here is my layout:

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Here is the development design guide that I use: https://nimbelink.com/Documentation/Skywire/1001594_Skywire_Hardware_Developers_Guide.pdf

I feel like I get the proper power, I get 3.6V at about 1Ah. But the modem doesnt turn on, Ive been trying to see if I get the proper frequency of the U19 - TPL5111DDCR device, but its hard to measure it with the oscilioscope.

Has anyone done this before and has does have some tips? :slight_smile:

Thanks in advance!

Best regards, Max

2

Since a lot of informaiton is missing I will take a SWAG and say I beleive your power supply if very light. This is from section 5.2 of the data you linked:

NimbeLink modems will regularly consume high amounts of current on their Power Supply
input (Pin 1, VCC), up to 1.5A during LTE transmits and receives, and GSM connections will
repeatedly hit 2A during transmissions. These current transients will often take the modem
from consuming ~100mA to >1A in just a few microseconds.

In order to maintain compatibility with other 4G NimbeLink modems, the baseboard power
supply should be designed to support peak currents of at least 2 Amps. The power trace leading from the power supply must be wide enough to ensure a low inductance path
between the power supply, capacitors, and the VCC pin.

I also believe you will have better success if you switch Vcc in place of ground.