LTM4625 Output Noise

Hi team

Two LTM4625s were designed as the circuit attached.
The same circuit was used to apply to two models.
I made the artwork as below.
The circuit with the GND on the 1-Layer produces noise.
The total number of floors is about 70 layers. 70-layer (about 10-layer GND) There is a GND in between.

Can you tell me what the problem is?
Is there anything you shouldn't do on the Artwork?




  • 0
    •  Analog Employees 
    on Oct 23, 2020 1:47 AM 4 months ago

    Hi Damon,

    I will also recommend that you consult this with a local ADI FAE for better support.

    There could be possible coupling of Vin noise to adjacent module, There is better order and improved separation between any Vin, Vout copper on the ‘good’ version. It is important to note that Vin can be noisy and can couple to sensitive traces (such as Freq, FB, CLKIN) if routed nearby. Sufficient GND copper isolation between noisy traces / planes should be included to minimize coupling. Please also note to route the CLKIN and CLKOUT lines away from any noise sources, FREQ pin and each other. Considering these notes, double check routing for these sensitive pins to compare if that may also help explain the behavior differences. The DC2171A layout provides a good reference.