Activity for DavidE‭

Type	On...	Excerpt	Status	Date
Comment	Post #285367	Olin thanks for the response. When you design a PCB for CAN or Ethernet, do you design the differential pair as loosely coupled or tightly coupled, or have you done both ways? What drives your choice? Are there any differential signal types that you have found, or have heard of, the need to ... (more)	—	over 2 years ago
Comment	Post #281353	Olin, I have a follow question. For the microcontrollers that I see require the center tap on the transformer be tied to VDD, the Tx+ and Tx- pins are each pulled up to VDD with a 50 ohm resistor. Is the 50 ohms to match any signals reflected from the load by looking like a 100ohm differential sour... (more)	—	about 3 years ago
Comment	Post #281353	Thanks for the extra information on the center tap. I have noticed that microcontrollers with the center tap requirement for their PHY use a pin called Rbias that needs a resistor to the return. Is rbias used for precisely setting the current sunk by Q1 and Q2 in your schematic? This current sink ma... (more)	—	about 3 years ago
Comment	Post #280733	I like how Andy’s answer also considers the impact of the probe on the system. (more)	—	about 3 years ago
Comment	Post #280714	Great answer by Olin. I think the answer does raise the question, why is the oscilloscope chassis and probe common being tied to earth ground if the earth ground is not benefiting the measurement? I think the answer is that the earth ground is there for electrical shock safety (same reason we elect... (more)	—	about 3 years ago
Comment	Post #281353	Hi Olin. Thanks for the response. Would you elaborate on how the center tap tied to VDD reduces the driver complexity for a single supply system? I’m having difficulty understanding how the center tap allows for the use of low side drivers. (more)	—	about 3 years ago