Mdthbs

Cases with long math equation

NRPE script for monitoring load average

A trip to the library

Would the USA be eligible to join the European Union?

Go to last file in vim

Stephen King and steam/diesel/cyber-punk

What are those bumps on top of the Antonov-225?

How would armour (and combat) change if the fighter didn't need to actually wear it?

Help, I cannot decide when to start the story

Does an Irish VISA WARNING count as "refused entry at the border of any country other than the UK?"

Why aren't rainbows blurred-out into nothing after they are produced?

Are there examples in Tanach of 3 or more parties having an ongoing conversation?

Scam? Phone call from "Department of Social Security" asking me to call back

What is a "soap"?

Doesn't the speed of light limit imply the same electron can be annihilated twice?

Big number puzzle

Shifting tenses in the middle of narration

Crippling fear of hellfire &, damnation, please help?

Locked Room Murder!! How and who?

Is there a fallacy about "appeal to 'big words'"?

Escape Velocity - Won't the orbital path just become larger with higher initial velocity?

How can I find an old paper when the usual methods fail?

Are there any cons in using rounded corners for bar graphs?

What is the most difficult concept to grasp in Calculus 1?

Weird resistor with dots around it

4-terminal shunt resistorBest shunt resistor for power meter application?Resistor symbol with a dotUnusual resistor symbol: resitor with Z overlaidTwo resistors in seriesWhy is there a resistor bridge before the amplifier?Power rating on Zero Ohm resistorResistor simplificationWhat is this schematic symbol? Transistor ? Variable Inductor

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}

17

2

$begingroup$

I was looking through the LTC4041 datasheet and saw this:

The 10mOhm resistor with the two nodes really close to it - is that a "special" resistor or something? Why have they drawn it like that?

resistors symbol

share|improve this question

edited 10 hours ago

Joel Reyes Noche

19211 gold badge11 silver badge1010 bronze badges

asked yesterday

AlfroJang80AlfroJang80

72255 silver badges1616 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Those dots are actually little different than the other dots indicating nodes on the schematic.
  $endgroup$
  – DKNguyen
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I would expect a 10mΩ resistor to have four terminals. See also en.wikipedia.org/wiki/Resistor#Ammeter_shunts
  $endgroup$
  – OrangeDog
  10 hours ago
  

  
  
  
  

add a comment | 

17

2

$begingroup$

I was looking through the LTC4041 datasheet and saw this:

The 10mOhm resistor with the two nodes really close to it - is that a "special" resistor or something? Why have they drawn it like that?

resistors symbol

share|improve this question

edited 10 hours ago

Joel Reyes Noche

19211 gold badge11 silver badge1010 bronze badges

asked yesterday

AlfroJang80AlfroJang80

72255 silver badges1616 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Those dots are actually little different than the other dots indicating nodes on the schematic.
  $endgroup$
  – DKNguyen
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I would expect a 10mΩ resistor to have four terminals. See also en.wikipedia.org/wiki/Resistor#Ammeter_shunts
  $endgroup$
  – OrangeDog
  10 hours ago
  

  
  
  
  

add a comment | 

$begingroup$

I was looking through the LTC4041 datasheet and saw this:

The 10mOhm resistor with the two nodes really close to it - is that a "special" resistor or something? Why have they drawn it like that?

resistors symbol

share|improve this question

edited 10 hours ago

Joel Reyes Noche

19211 gold badge11 silver badge1010 bronze badges

asked yesterday

AlfroJang80AlfroJang80

72255 silver badges1616 bronze badges

$endgroup$

share|improve this question

edited 10 hours ago

Joel Reyes Noche

19211 gold badge11 silver badge1010 bronze badges

asked yesterday

AlfroJang80AlfroJang80

72255 silver badges1616 bronze badges

share|improve this question

edited 10 hours ago

Joel Reyes Noche

19211 gold badge11 silver badge1010 bronze badges

asked yesterday

AlfroJang80AlfroJang80

72255 silver badges1616 bronze badges

edited 10 hours ago

Joel Reyes Noche

19211 gold badge11 silver badge1010 bronze badges

edited 10 hours ago

Joel Reyes Noche

19211 gold badge11 silver badge1010 bronze badges

asked yesterday

AlfroJang80AlfroJang80

72255 silver badges1616 bronze badges

asked yesterday

AlfroJang80AlfroJang80

72255 silver badges1616 bronze badges

2 Answers
2

active

oldest

votes

41

$begingroup$

Those are just junction dots like all of the others nearby, to show where 3 wires connect. This is called a Kelvin connection. The idea is that the connection should be as close as possible to the resistor. There are also some 4-terminal resistors made especially for this purpose.

See Four-terminal sensing on Wikipedia for more information.

share|improve this answer

answered yesterday

JustinJustin

4,0961515 silver badges2525 bronze badges

$endgroup$

add a comment | 

41

$begingroup$

It is a regular sense resistor with a kelvin connection. The dots are there to show a connection with the wires. A kelvin connection measures the current through the sense resistor for the DC to DC converter.

It is important to make the connection to avoid parasitic resistance in the traces as shown below. If the traces are placed outside of the resistor, the resistance of the traces can add with the resistor, where most resistances are in the kΩ, a few mΩ from the traces won't make a difference. In the case of sense resistors, a few mΩ from traces can contribute to large errors.

Running the traces on the inside of the sense resistor ensures that no current is flowing through the sense traces (because voltage measurements need to be high impedance).

4-terminal shunt resistors can be used that provide a kelvin connection internal to the resistor, and provide better accuracy, especially in high current applications.

Source: 4-terminal shunt resistor

share|improve this answer

edited 38 mins ago

answered yesterday

Voltage SpikeVoltage Spike

36.4k1212 gold badges4242 silver badges104104 bronze badges

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  I'm intrigued. Does one need to buy a ten milli-ohm resistor? (I never knew they sold such a thing). I would have guessed that about an inch of a PCB trace would be ten milli-ohms. Heat dissipation would be 25mW at 2.5A.
  $endgroup$
  – nigel222
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  5
  

  
  
  
  
  
  

  
  $begingroup$
  A 10milli ohm resistor can be a great deal smaller then a inch long! Also less temperature sensitive and less prone to PCB board process variations. It is a very standard sort of part in switched mode power applications where current mode control is popular.
  $endgroup$
  – Dan Mills
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  @nigel222 PCB traces can be used as resistors, but its best to buy resistors that have better temperature coefficients
  $endgroup$
  – Voltage Spike
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Your answer should say why picture #2 is bad: any current flowing through sections of unknown resistance between the sense wires will degrade measurement accuracy. In the first picture, the only thing current flows through between the sense wires is the calibrated resistor. In the second, however, the current being measured also flows through two uncalibrated traces between the sense wires.
  $endgroup$
  – supercat
  1 hour ago
  

  
  
  
  

add a comment | 

Your Answer

StackExchange.ifUsing("editor", function () {
return StackExchange.using("schematics", function () {
StackExchange.schematics.init();
});
}, "cicuitlab");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "135"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f452845%2fweird-resistor-with-dots-around-it%23new-answer', 'question_page');
}
);

Post as a guest

Name

Email

Required, but never shown

41

$begingroup$

Those are just junction dots like all of the others nearby, to show where 3 wires connect. This is called a Kelvin connection. The idea is that the connection should be as close as possible to the resistor. There are also some 4-terminal resistors made especially for this purpose.

See Four-terminal sensing on Wikipedia for more information.

share|improve this answer

answered yesterday

JustinJustin

4,0961515 silver badges2525 bronze badges

$endgroup$

add a comment | 

41

$begingroup$

Those are just junction dots like all of the others nearby, to show where 3 wires connect. This is called a Kelvin connection. The idea is that the connection should be as close as possible to the resistor. There are also some 4-terminal resistors made especially for this purpose.

See Four-terminal sensing on Wikipedia for more information.

share|improve this answer

answered yesterday

JustinJustin

4,0961515 silver badges2525 bronze badges

$endgroup$

add a comment | 

$begingroup$

Those are just junction dots like all of the others nearby, to show where 3 wires connect. This is called a Kelvin connection. The idea is that the connection should be as close as possible to the resistor. There are also some 4-terminal resistors made especially for this purpose.

See Four-terminal sensing on Wikipedia for more information.

share|improve this answer

answered yesterday

JustinJustin

4,0961515 silver badges2525 bronze badges

$endgroup$

share|improve this answer

answered yesterday

JustinJustin

4,0961515 silver badges2525 bronze badges

answered yesterday

JustinJustin

4,0961515 silver badges2525 bronze badges

answered yesterday

JustinJustin

4,0961515 silver badges2525 bronze badges

41

$begingroup$

It is a regular sense resistor with a kelvin connection. The dots are there to show a connection with the wires. A kelvin connection measures the current through the sense resistor for the DC to DC converter.

It is important to make the connection to avoid parasitic resistance in the traces as shown below. If the traces are placed outside of the resistor, the resistance of the traces can add with the resistor, where most resistances are in the kΩ, a few mΩ from the traces won't make a difference. In the case of sense resistors, a few mΩ from traces can contribute to large errors.

Running the traces on the inside of the sense resistor ensures that no current is flowing through the sense traces (because voltage measurements need to be high impedance).

4-terminal shunt resistors can be used that provide a kelvin connection internal to the resistor, and provide better accuracy, especially in high current applications.

Source: 4-terminal shunt resistor

share|improve this answer

edited 38 mins ago

answered yesterday

Voltage SpikeVoltage Spike

36.4k1212 gold badges4242 silver badges104104 bronze badges

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  I'm intrigued. Does one need to buy a ten milli-ohm resistor? (I never knew they sold such a thing). I would have guessed that about an inch of a PCB trace would be ten milli-ohms. Heat dissipation would be 25mW at 2.5A.
  $endgroup$
  – nigel222
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  5
  

  
  
  
  
  
  

  
  $begingroup$
  A 10milli ohm resistor can be a great deal smaller then a inch long! Also less temperature sensitive and less prone to PCB board process variations. It is a very standard sort of part in switched mode power applications where current mode control is popular.
  $endgroup$
  – Dan Mills
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  @nigel222 PCB traces can be used as resistors, but its best to buy resistors that have better temperature coefficients
  $endgroup$
  – Voltage Spike
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Your answer should say why picture #2 is bad: any current flowing through sections of unknown resistance between the sense wires will degrade measurement accuracy. In the first picture, the only thing current flows through between the sense wires is the calibrated resistor. In the second, however, the current being measured also flows through two uncalibrated traces between the sense wires.
  $endgroup$
  – supercat
  1 hour ago
  

  
  
  
  

add a comment | 

41

$begingroup$

It is a regular sense resistor with a kelvin connection. The dots are there to show a connection with the wires. A kelvin connection measures the current through the sense resistor for the DC to DC converter.

It is important to make the connection to avoid parasitic resistance in the traces as shown below. If the traces are placed outside of the resistor, the resistance of the traces can add with the resistor, where most resistances are in the kΩ, a few mΩ from the traces won't make a difference. In the case of sense resistors, a few mΩ from traces can contribute to large errors.

Running the traces on the inside of the sense resistor ensures that no current is flowing through the sense traces (because voltage measurements need to be high impedance).

4-terminal shunt resistors can be used that provide a kelvin connection internal to the resistor, and provide better accuracy, especially in high current applications.

Source: 4-terminal shunt resistor

share|improve this answer

edited 38 mins ago

answered yesterday

Voltage SpikeVoltage Spike

36.4k1212 gold badges4242 silver badges104104 bronze badges

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  I'm intrigued. Does one need to buy a ten milli-ohm resistor? (I never knew they sold such a thing). I would have guessed that about an inch of a PCB trace would be ten milli-ohms. Heat dissipation would be 25mW at 2.5A.
  $endgroup$
  – nigel222
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  5
  

  
  
  
  
  
  

  
  $begingroup$
  A 10milli ohm resistor can be a great deal smaller then a inch long! Also less temperature sensitive and less prone to PCB board process variations. It is a very standard sort of part in switched mode power applications where current mode control is popular.
  $endgroup$
  – Dan Mills
  9 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  @nigel222 PCB traces can be used as resistors, but its best to buy resistors that have better temperature coefficients
  $endgroup$
  – Voltage Spike
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Your answer should say why picture #2 is bad: any current flowing through sections of unknown resistance between the sense wires will degrade measurement accuracy. In the first picture, the only thing current flows through between the sense wires is the calibrated resistor. In the second, however, the current being measured also flows through two uncalibrated traces between the sense wires.
  $endgroup$
  – supercat
  1 hour ago
  

  
  
  
  

add a comment | 

$begingroup$

It is a regular sense resistor with a kelvin connection. The dots are there to show a connection with the wires. A kelvin connection measures the current through the sense resistor for the DC to DC converter.

It is important to make the connection to avoid parasitic resistance in the traces as shown below. If the traces are placed outside of the resistor, the resistance of the traces can add with the resistor, where most resistances are in the kΩ, a few mΩ from the traces won't make a difference. In the case of sense resistors, a few mΩ from traces can contribute to large errors.

Running the traces on the inside of the sense resistor ensures that no current is flowing through the sense traces (because voltage measurements need to be high impedance).

4-terminal shunt resistors can be used that provide a kelvin connection internal to the resistor, and provide better accuracy, especially in high current applications.

Source: 4-terminal shunt resistor

share|improve this answer

edited 38 mins ago

answered yesterday

Voltage SpikeVoltage Spike

36.4k1212 gold badges4242 silver badges104104 bronze badges

$endgroup$

share|improve this answer

edited 38 mins ago

answered yesterday

Voltage SpikeVoltage Spike

36.4k1212 gold badges4242 silver badges104104 bronze badges

answered yesterday

Voltage SpikeVoltage Spike

36.4k1212 gold badges4242 silver badges104104 bronze badges

answered yesterday

Voltage SpikeVoltage Spike

36.4k1212 gold badges4242 silver badges104104 bronze badges