Recent content by chakr

Hi, I tried different ways to fight the noise. In the end, the only thing that actually helped is Earth ground. I connected my device ground return to an Earth ground through Y-type capacitors. It reduced the noise to acceptable levels. The only thing is that this solution is not practical in my...

I am going to find a better capacitor. RF type.

Hi everyone, I am placing an order for some inductor chokes and ceramic capacitors. If I am successful, or should I say when I succeed, I will post my solution. I am also placing an order for a demo board with my LDO to verify if I make a layout error. Thank you, everyone. It was a great help.

Yes, in the picture it is the hub. It is actually a 5V charger. The unit has an option to run from AA batteries. Sometimes it needs to run from AC. This charger has both conducted and EMI noise. Such a poor design. I opened it. It looked inside very unattractive.

I I agree, my mistake. The problem is that people plug in the device into anything that has a USB port in it and not everything works :).

Hi Jim, I am going to order a demo board for the TPS73701DCQR, TPS73701DRVEVM-529, to verify my layout. If the output from the demo board is not noisy, then I have a layout issue.

Hi Jim, hopefully, the layout is not too messed up. I have ground plane polygons on the internal layers. They make about 70-80% of the surface area of layers 2 and 3. I think a large inductor or maybe 2 inductors on 5V and GND lines could help to reduce the noise. I am not sure about the values...

Hi Rive, I have a USB off-line AC power supply I have selected for this product. The power supply works fine. When I power the sensor from the hub temperature reading on my device changes significantly. The noise generated inside the hub affects circuits inside. Thank you.

Thank you, this one looks promising.

Hi Rive, the hub is powered from straight AC. I have attached an image from my scope that shows the noise. The scope shows noise from the hub even when it is not connected to my device.

Hi, I tried to add a capacitor to the USB connector. Unfortunately, it didn't help. The ground areas on the top layer are broken because I have components. Internal layers have continuous ground planes, but I do not have a dedicated ground layer. Maybe that is the problem? My choice of the input...

Thank you, Jim C33 is a ceramic cap (GRM188R60J106ME47D) . I will try to place my scope the way you recommend. C33 is very close to the LDO. C33 goes straight into the ground via a VIA connection.

Thank you, I can try that.

I can add a separate filter circuit between the USB cable and the Sensor node. Do you think it will help?