5 votes

Ethernet transformer

Ethernet is a digital signaling standard. Pulses must be sent and received, over a modest distance (~100m), without consuming excessive power, avoiding random errors, and tolerating ambient noise (...
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  • 2,413
4 votes

PCB Ethernet instability - CM4 Breakout Board

Ethernet should be an isolated interface. Which means the PHY side signals and cable side signals should not be referenced with each other as they are isolated with the transformer. This isolation ...
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3 votes

Ethernet transformer

Can someone tell me what is the meaning of Open circuit inductance That's the inductance of a winding when all the other winding(s) are left open (Similarly, the inductance measured when all the ...
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3 votes

Is there a digital to analog converter module in network cards?

Do they have a DAC module? Yes. It usually is an integral part of transmit path in the PHY, or an integrated PHY-MAC chip, sometimes embedded in the SoC/MCU. So, the "module" is there, but ...
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3 votes

Which data transfer speed (connection protocol) do I need?

Without further details in the question, 6 channels @ 250ksps, 16 bits = 6x250000x2 = 3MBytes/s 2 ADCs on your board = 6 MBytes/s 124 channels (presumably 11 boards) = 62 MB/s Unless many channels ...
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3 votes

Which data transfer speed (connection protocol) do I need?

The absolute minimum sample rate to see 25 kHz is 50 kHz. 124 channels to sample times 16 bit resolution times sample rate = 99.2 MBit/s required. The two ADCs with 6 channels each can deliver 48 MBit/...
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  • 1,889
2 votes

Ethernet transformer

In transformers, we distinguish between excitation current and magnetizing current. The excitation current represents energy passed from primary to secondary. The magnetizing current represents energy ...
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  • 1,601
2 votes

Ethernet: uses baseband line coding?

Is ethernet baseband line coded without the presence of multiple carrier frequencies signaling over the line? The ethernet you're probably referring to (the one over twisted copper cable with RJ45 ...
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2 votes
Accepted

Voltage mode Ethernet PHY and Current mode Ethernet PHY

Can anyone tell me the reason why the center taps of magnetics are shorted in case of connection to a current mode PHY They aren't shorted but connected to Vcc. This is because the PHY driver ports ...
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2 votes
Accepted

Capacitors on center tap

Why do we add capacitors on center taps to the magnetics when connecting to an Ethernet PHY? I would say that protection of victim electronics (blue below) from capacitively coupled line surges is ...
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  • 384k
2 votes

Capacitors on center tap

Why do we add capacitors on center taps to the magnetics when connecting to an Ethernet PHY? Normally we don't have to. I mean, it depends on the PHY chip. Most applications suggest that the PHY-side ...
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2 votes

DE-9 Connector for 100BaseTX Ethernet - How to assign pinout?

You might be better served by using one of the multitude of industrial shielded connectors designed for Ethernet. An M12 connector would be the usual choice, and then you can use standard industrial ...
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2 votes

Does anyone recognize this schematic symbol? (Ethernet connector)

FL11 is most likely a ferrite chip bead. VDD to the transformer center tap shouldn't be higher than the VDD of your ethernet PHY because even if it has open drain output, there are probably diodes ...
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  • 10.8k
2 votes

Which data transfer speed (connection protocol) do I need?

A bandwidth of 25 kHz will require a sample rate somewhat larger than 50 kHz so, to give yourself some headroom for anti-alias filters and reconstruction filters, choose a sampling rate of 60 kHz. ...
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  • 384k
1 vote
Accepted

Does anyone recognize this schematic symbol? (Ethernet connector)

FL11 is likely just a ferrite bead. But as it is greyed out and reads "DNI" it means it is not populated in the circuit, so 1V8 would not be connected to connector. The diagram is only an ...
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1 vote
Accepted

What is the impact of different values on the internal capacitor in the magnetics

The capacitors in question are decouplers for the centre-taps of the ethernet transformers and are not critical in value. Similarly, many designers use 100 nF decouplers on ICs on a PCB and, there are ...
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