No.
ºC and K are temperatures referenced to their "zero".
Heatsink thermal resistance (Rth s-a) has units of C/W; the rise in centigrade degrees for each Watt of input power.
does not compute.
1ºC is the temperature that is one centigrade degree above the 0ºC reference.
adding "/W" after a temperature does not make any physical sense.
This is the correct use of temperature
You are referring to a temperature inside the box.
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One could use a regulated 81.9Vdc and still be within the maximum of 82Vdc specified by National for the device.
No both of your examples are using the wrong units.
It should not use K
K is Kelvin and is a temperature referenced to absolute zero i.e. ~-273ºC
ºC is also a temperature.
The unit for Rth is C/W
Andrew, I respect Your knowledge but as You says many suppliers making big mistakes in many specifications ...
Here is one with K/W
"Thermal Resistance 1K/W"
345AB1000B | Heatsink 1K/W 120x100x37mm | ABL Components
And other with °C/W
"Thermal Resistance: 1°C/W"
HEAT SINK, 1CW; External Diameter ...
As I know, both "°C/W" and "K/W" are valid and represent the same unit in a manner of technical performance of heat sink, Thermal Resistance or Rth.
Here is one with K/W
"Thermal Resistance 1K/W"
345AB1000B | Heatsink 1K/W 120x100x37mm | ABL Components
And other with °C/W
"Thermal Resistance: 1°C/W"
HEAT SINK, 1CW; External Diameter ...
As I know, both "°C/W" and "K/W" are valid and represent the same unit in a manner of technical performance of heat sink, Thermal Resistance or Rth.
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seems like we have living android on this forum, that would explain incredible use of maths .now serious, would single supply operation give higher intermodulation distortion becouse of cap at out??
is heatsink resistance how fast heatsink can get rid of heat from one point to air, simply speaking?
rate of heat flow, rather than "how fast".
Rth tells us the resistance.
Just like volts, ohms and amps V=IR, we have temperature difference (equivalent to volts) Thermal resistance (Rth is equivalent to ohms) and heat flow in Watts (equivalent to amps), where deltaT = WRth
If you have 4W as the rate of heat flow and 3C/W as the thermal resistance, you can compute the unknown deltaT = 4W * 3C/W = 12Centigrade degrees.
Note I have not typed 12ºC for the deltaT.
DeltaT is a temperature difference. We do not use º for a temperature difference, DeltaT is just C, or C degrees, or Centigrade degrees
Rth tells us the resistance.
Just like volts, ohms and amps V=IR, we have temperature difference (equivalent to volts) Thermal resistance (Rth is equivalent to ohms) and heat flow in Watts (equivalent to amps), where deltaT = WRth
If you have 4W as the rate of heat flow and 3C/W as the thermal resistance, you can compute the unknown deltaT = 4W * 3C/W = 12Centigrade degrees.
Note I have not typed 12ºC for the deltaT.
DeltaT is a temperature difference. We do not use º for a temperature difference, DeltaT is just C, or C degrees, or Centigrade degrees
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Heatsink resistance is analogous with electrical resistance: it defines a specific heat flow through the heat sink resulting from the temperature difference between the point where the heat is generated and the ambient temperature.
Like an electrical resistance, where it specifies a certain electrical current through it as a result of a voltage difference between its ends.
In both cases you need to know the 'output impedance' of the source to know how much the source voltage or source temperature drops when the load from the resistor or heatsink is attached.
Jan
Probably not.
AC coupling is often used where there is a voltage difference between stages/modules.
We can get very good performance with Direct Current coupling and with Alternating Current coupling. The difference between the two is that DC is blocked by the AC coupling method, i.e. the DC voltage on one side does not transfer to the DC voltage on the other side.
Celsius - Wikipedia, the free encyclopedia
From Wiki...
"Other languages, and various publishing houses, may follow different typographical rules."
The Finnish standard "SFS" follows what has been written in the links I provided and must therefore also be "wrong". The SFS was written before the age of Wiki.
I do not know the DIN standard.
I do not know the EU standard.
And I definitely do not know the Imperial Standard.
Thanks for that link.
It shows in the table that Kelvin temperature is K alone and not preceded with a °
Whereas Fahrenheit and Celcius/Centrigrade always have the ° as in -40°C or 213°F
the following extract also draws attention to avoiding ambiguity when describing temperature interval (or differences as I have referred to them) from actual temperature/s
Temperature difference and temperature are not the same and the structure/context must clear the risk of ambiguity.
"C degrees" although the Wiki Author claims as being non standard is a convenient way to write and speak temperature difference.
I wonder what the reference [28] has to say on it.
It shows in the table that Kelvin temperature is K alone and not preceded with a °
Whereas Fahrenheit and Celcius/Centrigrade always have the ° as in -40°C or 213°F
the following extract also draws attention to avoiding ambiguity when describing temperature interval (or differences as I have referred to them) from actual temperature/s
They suggest that the ambiguity is solved by reversing the degrees C to become C degrees. This is what I was taught in school and repeated at University.
Temperature difference and temperature are not the same and the structure/context must clear the risk of ambiguity.
"C degrees" although the Wiki Author claims as being non standard is a convenient way to write and speak temperature difference.
I wonder what the reference [28] has to say on it.
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It's SOP here (work) to trash, berate, admonish... anyone who says 4.5 degrees Kelvin.
They do not make that mistake twice..
jn
Here is one very efficient method to improve thermal conductivity of IC to heat sink
Those metal parts are used in one very unique Macola's High-End AMP design build with 4 x bridged/parallel LM3886 per channel (or 6x, I forget, was long time ago) … There is no schematic for that AMP currently …
Phillips and Motorola used similar heatsink for drivers. I dont know if still are .
so deltaT is just number(and cant be negative)(something like when you bet on same game but in different country so you win 7.5pounds in england but 10bucks in us) dependent on what unit is used in calculation before? where watts would be same everywhere.smaller resistance >faster heat flow but measured in some sort of coefficient?
The thermal resistance of a block of material in inch units is:
Rth (degrees C per watt) = thickness / (area times K)
K values (roughly)
copper 10. <==this is what the chip is soldered to
aluminum 5.
Beo 5.
alumina .89
thermal epoxy .06 <==this is above and below the chip and copper
mica .015 <==this is an insulator
The delta T of a block of material will be the Rth times the power dissipated.
jn
Rth (degrees C per watt) = thickness / (area times K)
K values (roughly)
copper 10. <==this is what the chip is soldered to
aluminum 5.
Beo 5.
alumina .89
thermal epoxy .06 <==this is above and below the chip and copper
mica .015 <==this is an insulator
The delta T of a block of material will be the Rth times the power dissipated.
jn
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