DP83848C: Connect issue with switching regulator 3.3 volt power source

Ramasubbu Venkatachalam

Prodigy 180 points

Part Number: DP83848C

Hi all,

I am using dp83848 ic for Ethernet communication along with stm32f407 micro controller

In my board i have taken 3.3 v power source from the switching regulator LM2596-3.3V for Ethernet and controller

Initially it was working fine and it established the communication with LAN

Now it,s not working with switching power source.but it is working with the linear supply from programmer kit of (mikro E)

(i think it was a linear supply)

so how can i resolve this issue, please help ...

over 7 years ago

0 Ross Pimentel over 7 years ago

TI__Mastermind 23675 points

Hi Ramasubbu,

Please send us a schematic. Do you have the recommended decoupling?
What you say it was initially working but not anymore, what changed?
What do you mean by initially working? I.e. link, frame transmission?

0 Ramasubbu Venkatachalam over 7 years ago in reply to Ross Pimentel

Prodigy 180 points

Hi,

Thanks,

Initially the frame transmission was happened now its not happening (Link establishment there is no issue)

am not sure whether i have used the recommended decoupling capacitor

I referred st development kit schematic for my design

Please find the one part of my schematic i have attached here

KRYO300_Main.pdf

0 Ross Pimentel over 7 years ago in reply to Ramasubbu Venkatachalam

TI__Mastermind 23675 points

Hi Ramasubbu,

Can you send me a register dump from 0x0 to 0x1F?
Also, what has changed from when it was working to when it was not?
From your initial comments it sounds like nothing.
Does it only work with an LDO? Or it did work with a switcher but now only works with an LDO?
Can you send a screen capture of the MDI waveform with a 100 ohm termination across the TD+/- pins and the RD+/- pins?

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DP83848C: Connect issue with switching regulator 3.3 volt power source