The matching device placed at the end of a trace that is acting as a transmission line. This termination prevent reflections from the end of the line and ensures a complete transfer of energy in the waveform into the receiving unit.

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2answers
39 views

Termination resistor creating communication problem in RS485 MODBUS/TCP

In RS485 communication, what is the role of termination resisotor. Is it mandatory? I have been working on a project with MODBUS/TCP over RS485 where upto 32 slaves are there in some links, out of ...
3
votes
1answer
115 views

Transimpedance-amplifier with 2nd order filter (termination and derivation of transfer function)

I have this schematic from the datasheet of the amp OPA380 (page 12, figure 6c) with a low noise 2nd order filter. I would like to derive the transfer function analytically of this op-amp to get the ...
1
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1answer
37 views

Implementing CAN bus software termination

I noticed that a lot of CAN new test equipment allow you to enable/disable the termination via software. Is there an new transceiver in the market or an accepted way to implement this??
4
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1answer
76 views

Clock Oscillator - Topology and PCB Layout recommendations

I'm designing one of my first layouts and I've read a lot of articles and StackExchange questions about guidelines and recommendations. It's a university project realized by another student that I ...
3
votes
1answer
87 views

SPI bus termination and pull-up resistors

My microcontroller (ATMEL series) needs to communicate to a slave device using SPI protocol. I am designing the hardware. The maximum SPI bus speed is 1 MHz. The distance between the master and slave ...
4
votes
1answer
53 views

ECL output termination

This is a rookie question, but I'm quite confused about the ECL termination used on the ADCMP565 evaluation board First, in the IC datasheet, they show how to terminate the ECL outputs to drive 50Ω ...
7
votes
3answers
360 views

SPI bus connections - to loop or not to loop?

I have a question regarding the physical connection of an SPI bus. I have an SPI master (a PIC32 device) and a number of slaves (in this case PIC16 devices). I'm only writing to the slaves, and the ...
1
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2answers
66 views

On board signal termination

and thanks for bothering with my problem. I have a two signals A and B that I want to route using several alternative paths via jumpers on my board. In one of the occasions I need to use the same ...
1
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1answer
55 views

JTAG Clock line Termination

The performance of my self-made JTAG cable isn't great, I can clock it up to 1.5Mhz max. I've read that terminating the clock line is a thing so I investigated: One solution suggested to add a ...
1
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1answer
53 views

Using different termination types on CAN bus

Is it possible to terminate one end of a CAN bus using Standard termination (single 120 ohm resistor across CANH and CANL) and the other end using Split termination (two 60 ohm in series with a ...
0
votes
1answer
39 views

DDR2 ODT pulled low

I was looking at a DDR2 design that had it's ODT pin pulled low, presumably this was done because the CPU doesn't have and ODT pin. Reading the datasheet though I don't see a clear explanation of ...
1
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1answer
150 views

CAN network resistor termination [duplicate]

My question is about the resistor for termination in a CAN network. From an electrical perspective why should we add this resistor (commonly 120 Ohm) between the CAN_H and CAN_L? Thanks in advance.
2
votes
3answers
120 views

How to terminate switching transistor for level change?

For a typical driver, I would add a series termination resistor to terminate the line. But what would be the correct way to terminate when a transistor is used to level shift a 3.3V/5V signal to some ...
1
vote
2answers
182 views

Termination of unused PoE pairs

How important are the specific termination values used for PoE pairs (pins 4&5, 7&8)? Below is the recommended Ethernet front end for Micrel’s KSZ8841/42. http://www.micrel.com/_PDF/...
4
votes
1answer
267 views

USB hub and slave on same pcb - are serial resistors and capacitors needed?

I'm building a device using TUSB2046B hub controller 4x FT230X USB to UART controller First, let's look on Hub controller sample application: Note D: All USB DP, DM signal pairs require ...
1
vote
0answers
54 views

Clock signal sharpness

I'm currently tuning the termination resistors in the clock circuit. The resistor here is 330 ohms, I got a rippled clock signal like this: I increased both resistors value to 430 ohms and I got: ...
1
vote
3answers
522 views

How to choose the impedance of a BNC adapter?

I am trying to set up lab equipment to measure my soon-to-come sample, but I couldn't get my mind around one thing, impedance termination. I will tell you what I have, what I want to get, and my ...
2
votes
1answer
186 views

Terminating unused unity-gain Unstable op-amp

I am trying to terminate the unused unity-gain unstable op-amp. I have tried to terminate it with the typical unity-gain stable configuration (http://www.maximintegrated.com/en/app-notes/index.mvp/id/...
5
votes
1answer
572 views

Why is there such a huge price range for BNC terminators? [closed]

I wanted to buy some standard BNC 50 Ohm terminators and was surprised when I saw multiple offers with prices well above 20€ per piece. I found others for around 2€ (same online shop) and now I am ...
1
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1answer
247 views

USB data serial termination resistors. Need them for STM32F2 micro? If so, what wattage?

I'm a little confused. The STM32F2 datasheet says only this, vaguely stated in the features: HNP/SNP/IP inside (no need for any external resistor) Is that referring to the D+/D- termination ...
2
votes
1answer
760 views

What should I do with the unused Op-amp inputs?

I am building a simple inverting operational amplifier circuit where I am using a chip with dual amplifier. I am only using one of the two amplifiers. What should I do to the unused amplifier's input ...
1
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1answer
167 views

What should be the size/package of Bob Smith Termination resistor?

We have run into a layout issue where the size/package of the 75R resistor used for Bob Smith termination on unused Ethernet pins is in question. The current package of this resistor is 1206 and we ...
0
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1answer
275 views

Transmission line: Why do longer traces cause signal reflections?

As the question says, I want to know why do longer traces/longer lengths of non-terminated signals of the PCB cause reflections and not the short length ones? I am ignoring the negligible amount of ...
1
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0answers
125 views

For wrong termination resistor uses

Over 485-interface slaves are connected as multi drop, physically daisy chain. Those have built-in termination resistor, and the value is 120 ohm and no select switch for termination on/off. So it ...
17
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4answers
2k views

What and Why's of termination?

I am new to electronics, and don't understand what is termination and why it is needed, especially in digital communications. Thanks
0
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1answer
75 views

How subtle or dramatic are the effects of a impedance mismatch by a certain percentage?

If a trace is designed to be 50 ohms, how much of an effect would 10% or 20% mismatch between line impedance and termination values ? For instance, a 50 ohm line with 45 ohm or 55 ohm series ...
0
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2answers
247 views

Trace termination length limits

Are there any length limits to series termination ? If I have a trace that's 12 in or a trace that is 100 in, can the same series termination resistor be used (assuming that Zo = 50 ohm) ?
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3answers
321 views

How to select source termination resistors by looking at signal?

If I have two devices that some distance apart on a fairly large PCB (could be 1 in, or it could be 20 in). If I arbitrary select a value for R1, lets say 33 ohms in this example and if my digital ...
4
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2answers
3k views

Why is Bob Smith termination for Ethernet recommended if it's wrong?

I came across this article today (more detailed paper), which claims that the widely recommended Bob Smith termination (75-ohm resistor + 1000pF to chassis GND) may not be ideal (or correct). If this ...
0
votes
4answers
2k views

What are the main causes of Overshoot and undershoot of a signal?

I'm not an EE major, but I was curious what causes overshoot and undershoot. Where can i find a detailed explanation of the process? I heard it has to do with the parasitic capacitance, but there ...
2
votes
2answers
696 views

Causes of ringing in a PCB

Im trying to understand the source of ringing at the termination point of a PCB traces before i delve into actually designing a PCB. For example, by 'termination point', I mean a clock signal ...
0
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1answer
83 views

Termination of digital lines

So when exactly is termination of a digital signal required? In my case, I'm dealing with a 1.8V signal that comes from an FPGA. This signal connects to a high impedance input of an OpAmp. The trace ...
5
votes
5answers
2k views

Most ideal wire termination for round screw terminals

My '60 Volkswagen Beetle uses a number of electrical components that are equipped with round screw terminals, like you can see in the picture below: What is the most ideal wire termination for ...
0
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1answer
105 views

Cable screen terminations for enclosure containing SMPS and instrumentation signal conditioners

I'm looking for some help with some screening and cable termination decisions I need to make. I'd be grateful for any advice, and I'll do my best to explain myself clearly. I am building a control ...
0
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1answer
159 views

Termination resistors in Ethernet in Kilo-Ohms instead of Ohms?

When working with Ethernet, whether copper or optical fiber, why are the termination resistors always in a few ohms and never in kilo-ohms? Example: 49.9R on transmit & receive pair of PHY in ...
2
votes
1answer
224 views

Alternative to high Watt resistor terminating resistor

In the following circuit a 120 ohm termination resistor is placed across the Rx+ and Rx- data lines connected to a RS485/422 transceiver. The transceiver is protected up +/- 60V. simulate this ...
2
votes
2answers
152 views

Very long transmission-line design tips

I'm designing a very long transmission line between a master node a some slaves far away connected by a bus where only 3 wires are used: - A DC power supply (24vdc) - B Digital comm - C Ground As ...
6
votes
1answer
2k views

Bob Smith Termination with POE

I'm looking into doing a Bob Smith termination for a Power over Ethernet (POE) PSE. The TI app note shows the following termination: But all of TI's reference designs (and later figures in the same ...
1
vote
1answer
116 views

Terminating SDRAM on opposite side of board

I have a 4-layer board with the micro and sdram on opposite sides, the ram signals are short, but I still want to terminate them (I can test the board later and determine if I really need termination),...
2
votes
3answers
2k views

Load Resistor across Crystal

What is the purpose of using a 1M Ohm resistor across crystal pins? Please refer to the image for clarity. The crystal serves as the clock source for an USB Hub device(LAN9512). There is nothing ...
0
votes
5answers
646 views

Use transistor to connect terminating resistor for differential signal?

Is it okay to use a transistor to connect a terminating resistor between the A and B lines of a differential signal? I'm not sure because I know that at the source/emitter of an NPN transistor must be ...
1
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1answer
87 views

What is digital Termination and when is it used?

I have heard transmission line termination but today I came across this "Digital termination" but couldn't find out why is it used and what effect does it have on digital signals?
3
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5answers
1k views

How to use input/output termination resistors in filters?

NOTICE: I have added another question here that a solution for each one may help for solving the other one. Please look at Fig-1 below. It is a common usage of termination resistors. R1 , R2 work ...
1
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1answer
128 views

USB data lines: current consumption

I am designing a USB device and I can't find easily the USB specs about the maximum current consumption allowed for the D+ and D- lines. I am planning to use a 39Ω termination resistor on this ...
3
votes
2answers
714 views

SPI multiple slave termination

I've been reading about signal integrity and went through this site reading about it as well as other references. Alot of the topics deal with a single slave, but not so much multiple slaves. I'll be ...
2
votes
2answers
628 views

HD-SDI serial data output termination

Soo.. I've been testing my designing limits, trying to learn about Serial Digital Interface, and building a simple reclocker with TI IC's. And now I've run into a small speedbump with the output from ...
3
votes
1answer
446 views

USB Termination Resistor

I am using the Atmel AVR32 UC3C AT32UC3C2512C for a project and the datasheet doesn't say anything about terminating the USB connection, but the AVR32768 Application note, clearly points out a 39 ohm ...
7
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2answers
1k views

What is the importance of the \$50\Omega\$ resistors in this RF op-amp circuit?

From the TI application note RF and IF amplifiers with op amps: The source says "The 39-pF capacitor provides peaking to compensate for some high-frequency roll-off, but better IP3 performance can ...
3
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1answer
3k views

How do different methods of transmission line termination compare?

It seems to me that there are three ways to terminate a transmission line: at both ends at the load only at the source only simulate this circuit – Schematic created using CircuitLab ...
2
votes
2answers
561 views

Do I need to terminate extremely short traces (< 0.5 inches)?

Some background: I have a little hobby project running that basically interfaces a 64 pin ARM mcu (the STM32F405RGT6) to a stereo codec (a TI PCM3010) via I2S interface. I'm deriving the master clock ...