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Why hasn't my LED burned out by now?
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I have a 15 year old ReplayTV DVR. I got it used, I'm not sure when, but probably about a decade ago. It's turned on almost all the time, and it has a blue power LED on the front.
The LED FAQ says that many LEDs have a rated lifetime of 50,000 hours, which implies that it should only last about 5.5 years when used 24x7. Green Efficient Homes says that "an individual LED may well last 100,000 hours", so that bumps it up to 11 years.
These sites seem to be about LED light bulbs, not the individual LEDs that are used as indicators on electronic devices.
Why has this little guy been able to keep shining continuously for so long?
led
asked 58 mins ago
Barmar
1063
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up vote
1
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I have a 15 year old ReplayTV DVR. I got it used, I'm not sure when, but probably about a decade ago. It's turned on almost all the time, and it has a blue power LED on the front.
The LED FAQ says that many LEDs have a rated lifetime of 50,000 hours, which implies that it should only last about 5.5 years when used 24x7. Green Efficient Homes says that "an individual LED may well last 100,000 hours", so that bumps it up to 11 years.
These sites seem to be about LED light bulbs, not the individual LEDs that are used as indicators on electronic devices.
Why has this little guy been able to keep shining continuously for so long?
led
asked 58 mins ago
Barmar
1063
New contributor
Barmar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I have a 15 year old ReplayTV DVR. I got it used, I'm not sure when, but probably about a decade ago. It's turned on almost all the time, and it has a blue power LED on the front.
The LED FAQ says that many LEDs have a rated lifetime of 50,000 hours, which implies that it should only last about 5.5 years when used 24x7. Green Efficient Homes says that "an individual LED may well last 100,000 hours", so that bumps it up to 11 years.
These sites seem to be about LED light bulbs, not the individual LEDs that are used as indicators on electronic devices.
Why has this little guy been able to keep shining continuously for so long?
led
asked 58 mins ago
Barmar
1063
New contributor
Barmar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I have a 15 year old ReplayTV DVR. I got it used, I'm not sure when, but probably about a decade ago. It's turned on almost all the time, and it has a blue power LED on the front.
The LED FAQ says that many LEDs have a rated lifetime of 50,000 hours, which implies that it should only last about 5.5 years when used 24x7. Green Efficient Homes says that "an individual LED may well last 100,000 hours", so that bumps it up to 11 years.
These sites seem to be about LED light bulbs, not the individual LEDs that are used as indicators on electronic devices.
Why has this little guy been able to keep shining continuously for so long?
led
led
asked 58 mins ago
Barmar
1063
New contributor
Barmar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 58 mins ago
Barmar
1063
New contributor
Barmar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 58 mins ago
Barmar
1063
New contributor
Barmar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 58 mins ago
Barmar
1063
asked 58 mins ago
Barmar
1063
1063
New contributor
Barmar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Barmar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Barmar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
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4 Answers
4
active
oldest
votes
up vote
3
down vote
Properly designed, built and used, today's LEDs have incredibly long lives and the wearout mechanisms are not catastrophic in nature, so instead of using incandescent lamp MTBF statistics, a luminosity percentage (70%) is often used to define the lifetime- this doesn't mean that the LED burns out, it means that the light out put is only 70% of what it was when brand new. Because the change is slow, you normally don't notice it.
For white light applications this makes sense because after a period of time the light works but may be too dim to be useful in the application such as a flashlight or reading lamp.
FWIW incandescent lamps are prone to something similar in that the filament would slowly evaporate leaving an dark coating on the glass shell, dimming the light. They are able to compensate a little bit because the filament glows a bit brighter due to the increased resistance (until it breaks).
answered 32 mins ago
isdi
7616
I'm not talking about LEDs that are parts of bulbs that replace incandescent bulbs. I'm talking about single LEDs used as indicator lights.
– Barmar
26 mins ago
1
Its' the same technology. "white" LEDs as opposed to RGB types are a blue/ near-UV LED that stimulates a phosphor to give off white light, that's about the only difference (aside from the heterojunction materials etc.). If you wear glasses or know somebody, ask them about that annoying blue rainbow effect that they see in all the solid state car headlights- that's the active LED itself. Even if it's an indicator there's a cutoff point where it's too dim to be seen well.
– isdi
19 mins ago
add a comment |Â
up vote
1
down vote
The rating is only a MTBF (mean time between failure)
LED MTBF
For any component or system, the MTBF is the mean time between
failures. The MTBF is the elapsed time which is predicted between
inherent failures of a component or system during operation.
The MTBF is a figure used in calculations for the reliability of items
of equipment. In order to be able to calculate the MTBF of the
equipment, it is necessary to know the MTBF of the individual
components, e.g. the LED MTBF in this case.
The failure rate for a component, and the MTBF are linked. MTBF can be
calculated as the inverse of the failure rate if it is assumed that
there is a constant failure rate, which is not unreasonable as a first
order assumption.
MTBF = Hours of operation / Number of failures
The MTBF figures are often quoted in the manufacturers data sheets.
However the MTBF can be considerably reduced by operating components
close to their rated limits. Hostile environments such as high
temperature and vibration also reduce the MTBF.
However when run within their limits, the LED lamps have a long
lifetime, and do not fail very often.
Source: https://www.radio-electronics.com/info/data/semicond/leds-light-emitting-diodes/lifespan-lifetime-expectancy-mtbf.php
Without a sample population and testing of that specific LED it will be impossible to tell what the lifetime of that LED is. the manufacturer can only guarantee through what they know about that LED (probably through running it through months worth of testing, measuring the degradation) and then extrapolating that over the lifetime. They then guarantee an MTBF figure and if you get a batch of their LED's on average, they will last more than x amount of hours. But they could last more, the MTBF figure is only a lower bound.
answered 47 mins ago
laptop2d
22.2k123175
add a comment |Â
up vote
0
down vote
Those times are rated lifetimes and can be very conservative. So it might well be that most or (in case you are lucky) some of them can handle a factor times more, so 15 years sounds not unreasonable.
answered 54 mins ago
Michel Keijzers
5,22862357
add a comment |Â
up vote
0
down vote
Estimations of life expectancy of electronic components is a tricky business. As one can imagine, manufacturer can't wait 50,000 hours (or something like 2,290,000,000 hours for a RS232 receiver, see page 7 of this essay) to collect statistics of device failures, market doesn't allow this. All estimations are done using "accelerated models".
The idea is to set a batch of devices under extreme conditions (voltage, current, temperature, environmental factors) until some devices fail in a reasonable test time (days or hours), assuming no shift in failure mechanisms. Then, using some theoretical models of failure mechanisms and other ASSUMPTIONS, the failure rate gets extrapolated to normal operating conditions. Usually the theoretical models are of exponential type, so small errors during accelerated testing can result in vast differences in estimations for tails of these exponential functions. So the models are usually on a conservative side, to avoid liabilities from catastrophic premature failures.
For example, if the accelerated model for a LED did include the air humidity and rust/oxidation factor, but your LED was always at room and dry air conditions, it can last much-much longer than the manufacturer's specified MTBF.
answered 9 mins ago
Ale..chenski
24.4k11857
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
Properly designed, built and used, today's LEDs have incredibly long lives and the wearout mechanisms are not catastrophic in nature, so instead of using incandescent lamp MTBF statistics, a luminosity percentage (70%) is often used to define the lifetime- this doesn't mean that the LED burns out, it means that the light out put is only 70% of what it was when brand new. Because the change is slow, you normally don't notice it.
For white light applications this makes sense because after a period of time the light works but may be too dim to be useful in the application such as a flashlight or reading lamp.
FWIW incandescent lamps are prone to something similar in that the filament would slowly evaporate leaving an dark coating on the glass shell, dimming the light. They are able to compensate a little bit because the filament glows a bit brighter due to the increased resistance (until it breaks).
answered 32 mins ago
isdi
7616
I'm not talking about LEDs that are parts of bulbs that replace incandescent bulbs. I'm talking about single LEDs used as indicator lights.
– Barmar
26 mins ago
1
Its' the same technology. "white" LEDs as opposed to RGB types are a blue/ near-UV LED that stimulates a phosphor to give off white light, that's about the only difference (aside from the heterojunction materials etc.). If you wear glasses or know somebody, ask them about that annoying blue rainbow effect that they see in all the solid state car headlights- that's the active LED itself. Even if it's an indicator there's a cutoff point where it's too dim to be seen well.
– isdi
19 mins ago
add a comment |Â
up vote
3
down vote
Properly designed, built and used, today's LEDs have incredibly long lives and the wearout mechanisms are not catastrophic in nature, so instead of using incandescent lamp MTBF statistics, a luminosity percentage (70%) is often used to define the lifetime- this doesn't mean that the LED burns out, it means that the light out put is only 70% of what it was when brand new. Because the change is slow, you normally don't notice it.
For white light applications this makes sense because after a period of time the light works but may be too dim to be useful in the application such as a flashlight or reading lamp.
FWIW incandescent lamps are prone to something similar in that the filament would slowly evaporate leaving an dark coating on the glass shell, dimming the light. They are able to compensate a little bit because the filament glows a bit brighter due to the increased resistance (until it breaks).
answered 32 mins ago
isdi
7616
I'm not talking about LEDs that are parts of bulbs that replace incandescent bulbs. I'm talking about single LEDs used as indicator lights.
– Barmar
26 mins ago
1
Its' the same technology. "white" LEDs as opposed to RGB types are a blue/ near-UV LED that stimulates a phosphor to give off white light, that's about the only difference (aside from the heterojunction materials etc.). If you wear glasses or know somebody, ask them about that annoying blue rainbow effect that they see in all the solid state car headlights- that's the active LED itself. Even if it's an indicator there's a cutoff point where it's too dim to be seen well.
– isdi
19 mins ago
add a comment |Â
up vote
3
down vote
up vote
3
down vote
Properly designed, built and used, today's LEDs have incredibly long lives and the wearout mechanisms are not catastrophic in nature, so instead of using incandescent lamp MTBF statistics, a luminosity percentage (70%) is often used to define the lifetime- this doesn't mean that the LED burns out, it means that the light out put is only 70% of what it was when brand new. Because the change is slow, you normally don't notice it.
For white light applications this makes sense because after a period of time the light works but may be too dim to be useful in the application such as a flashlight or reading lamp.
FWIW incandescent lamps are prone to something similar in that the filament would slowly evaporate leaving an dark coating on the glass shell, dimming the light. They are able to compensate a little bit because the filament glows a bit brighter due to the increased resistance (until it breaks).
answered 32 mins ago
isdi
7616
Properly designed, built and used, today's LEDs have incredibly long lives and the wearout mechanisms are not catastrophic in nature, so instead of using incandescent lamp MTBF statistics, a luminosity percentage (70%) is often used to define the lifetime- this doesn't mean that the LED burns out, it means that the light out put is only 70% of what it was when brand new. Because the change is slow, you normally don't notice it.
For white light applications this makes sense because after a period of time the light works but may be too dim to be useful in the application such as a flashlight or reading lamp.
FWIW incandescent lamps are prone to something similar in that the filament would slowly evaporate leaving an dark coating on the glass shell, dimming the light. They are able to compensate a little bit because the filament glows a bit brighter due to the increased resistance (until it breaks).
answered 32 mins ago
isdi
7616
answered 32 mins ago
isdi
7616
answered 32 mins ago
isdi
7616
answered 32 mins ago
isdi
7616
7616
I'm not talking about LEDs that are parts of bulbs that replace incandescent bulbs. I'm talking about single LEDs used as indicator lights.
– Barmar
26 mins ago
1
Its' the same technology. "white" LEDs as opposed to RGB types are a blue/ near-UV LED that stimulates a phosphor to give off white light, that's about the only difference (aside from the heterojunction materials etc.). If you wear glasses or know somebody, ask them about that annoying blue rainbow effect that they see in all the solid state car headlights- that's the active LED itself. Even if it's an indicator there's a cutoff point where it's too dim to be seen well.
– isdi
19 mins ago
add a comment |Â
I'm not talking about LEDs that are parts of bulbs that replace incandescent bulbs. I'm talking about single LEDs used as indicator lights.
– Barmar
26 mins ago
1
Its' the same technology. "white" LEDs as opposed to RGB types are a blue/ near-UV LED that stimulates a phosphor to give off white light, that's about the only difference (aside from the heterojunction materials etc.). If you wear glasses or know somebody, ask them about that annoying blue rainbow effect that they see in all the solid state car headlights- that's the active LED itself. Even if it's an indicator there's a cutoff point where it's too dim to be seen well.
– isdi
19 mins ago
I'm not talking about LEDs that are parts of bulbs that replace incandescent bulbs. I'm talking about single LEDs used as indicator lights.
– Barmar
26 mins ago
I'm not talking about LEDs that are parts of bulbs that replace incandescent bulbs. I'm talking about single LEDs used as indicator lights.
– Barmar
26 mins ago
1
1
Its' the same technology. "white" LEDs as opposed to RGB types are a blue/ near-UV LED that stimulates a phosphor to give off white light, that's about the only difference (aside from the heterojunction materials etc.). If you wear glasses or know somebody, ask them about that annoying blue rainbow effect that they see in all the solid state car headlights- that's the active LED itself. Even if it's an indicator there's a cutoff point where it's too dim to be seen well.
– isdi
19 mins ago
Its' the same technology. "white" LEDs as opposed to RGB types are a blue/ near-UV LED that stimulates a phosphor to give off white light, that's about the only difference (aside from the heterojunction materials etc.). If you wear glasses or know somebody, ask them about that annoying blue rainbow effect that they see in all the solid state car headlights- that's the active LED itself. Even if it's an indicator there's a cutoff point where it's too dim to be seen well.
– isdi
19 mins ago
add a comment |Â
up vote
1
down vote
The rating is only a MTBF (mean time between failure)
LED MTBF
For any component or system, the MTBF is the mean time between
failures. The MTBF is the elapsed time which is predicted between
inherent failures of a component or system during operation.
The MTBF is a figure used in calculations for the reliability of items
of equipment. In order to be able to calculate the MTBF of the
equipment, it is necessary to know the MTBF of the individual
components, e.g. the LED MTBF in this case.
The failure rate for a component, and the MTBF are linked. MTBF can be
calculated as the inverse of the failure rate if it is assumed that
there is a constant failure rate, which is not unreasonable as a first
order assumption.
MTBF = Hours of operation / Number of failures
The MTBF figures are often quoted in the manufacturers data sheets.
However the MTBF can be considerably reduced by operating components
close to their rated limits. Hostile environments such as high
temperature and vibration also reduce the MTBF.
However when run within their limits, the LED lamps have a long
lifetime, and do not fail very often.
Source: https://www.radio-electronics.com/info/data/semicond/leds-light-emitting-diodes/lifespan-lifetime-expectancy-mtbf.php
Without a sample population and testing of that specific LED it will be impossible to tell what the lifetime of that LED is. the manufacturer can only guarantee through what they know about that LED (probably through running it through months worth of testing, measuring the degradation) and then extrapolating that over the lifetime. They then guarantee an MTBF figure and if you get a batch of their LED's on average, they will last more than x amount of hours. But they could last more, the MTBF figure is only a lower bound.
answered 47 mins ago
laptop2d
22.2k123175
add a comment |Â
up vote
1
down vote
The rating is only a MTBF (mean time between failure)
LED MTBF
For any component or system, the MTBF is the mean time between
failures. The MTBF is the elapsed time which is predicted between
inherent failures of a component or system during operation.
The MTBF is a figure used in calculations for the reliability of items
of equipment. In order to be able to calculate the MTBF of the
equipment, it is necessary to know the MTBF of the individual
components, e.g. the LED MTBF in this case.
The failure rate for a component, and the MTBF are linked. MTBF can be
calculated as the inverse of the failure rate if it is assumed that
there is a constant failure rate, which is not unreasonable as a first
order assumption.
MTBF = Hours of operation / Number of failures
The MTBF figures are often quoted in the manufacturers data sheets.
However the MTBF can be considerably reduced by operating components
close to their rated limits. Hostile environments such as high
temperature and vibration also reduce the MTBF.
However when run within their limits, the LED lamps have a long
lifetime, and do not fail very often.
Source: https://www.radio-electronics.com/info/data/semicond/leds-light-emitting-diodes/lifespan-lifetime-expectancy-mtbf.php
Without a sample population and testing of that specific LED it will be impossible to tell what the lifetime of that LED is. the manufacturer can only guarantee through what they know about that LED (probably through running it through months worth of testing, measuring the degradation) and then extrapolating that over the lifetime. They then guarantee an MTBF figure and if you get a batch of their LED's on average, they will last more than x amount of hours. But they could last more, the MTBF figure is only a lower bound.
answered 47 mins ago
laptop2d
22.2k123175
add a comment |Â
up vote
1
down vote
up vote
1
down vote
The rating is only a MTBF (mean time between failure)
LED MTBF
For any component or system, the MTBF is the mean time between
failures. The MTBF is the elapsed time which is predicted between
inherent failures of a component or system during operation.
The MTBF is a figure used in calculations for the reliability of items
of equipment. In order to be able to calculate the MTBF of the
equipment, it is necessary to know the MTBF of the individual
components, e.g. the LED MTBF in this case.
The failure rate for a component, and the MTBF are linked. MTBF can be
calculated as the inverse of the failure rate if it is assumed that
there is a constant failure rate, which is not unreasonable as a first
order assumption.
MTBF = Hours of operation / Number of failures
The MTBF figures are often quoted in the manufacturers data sheets.
However the MTBF can be considerably reduced by operating components
close to their rated limits. Hostile environments such as high
temperature and vibration also reduce the MTBF.
However when run within their limits, the LED lamps have a long
lifetime, and do not fail very often.
Source: https://www.radio-electronics.com/info/data/semicond/leds-light-emitting-diodes/lifespan-lifetime-expectancy-mtbf.php
Without a sample population and testing of that specific LED it will be impossible to tell what the lifetime of that LED is. the manufacturer can only guarantee through what they know about that LED (probably through running it through months worth of testing, measuring the degradation) and then extrapolating that over the lifetime. They then guarantee an MTBF figure and if you get a batch of their LED's on average, they will last more than x amount of hours. But they could last more, the MTBF figure is only a lower bound.
answered 47 mins ago
laptop2d
22.2k123175
The rating is only a MTBF (mean time between failure)
LED MTBF
For any component or system, the MTBF is the mean time between
failures. The MTBF is the elapsed time which is predicted between
inherent failures of a component or system during operation.
The MTBF is a figure used in calculations for the reliability of items
of equipment. In order to be able to calculate the MTBF of the
equipment, it is necessary to know the MTBF of the individual
components, e.g. the LED MTBF in this case.
The failure rate for a component, and the MTBF are linked. MTBF can be
calculated as the inverse of the failure rate if it is assumed that
there is a constant failure rate, which is not unreasonable as a first
order assumption.
MTBF = Hours of operation / Number of failures
The MTBF figures are often quoted in the manufacturers data sheets.
However the MTBF can be considerably reduced by operating components
close to their rated limits. Hostile environments such as high
temperature and vibration also reduce the MTBF.
However when run within their limits, the LED lamps have a long
lifetime, and do not fail very often.
Source: https://www.radio-electronics.com/info/data/semicond/leds-light-emitting-diodes/lifespan-lifetime-expectancy-mtbf.php
Without a sample population and testing of that specific LED it will be impossible to tell what the lifetime of that LED is. the manufacturer can only guarantee through what they know about that LED (probably through running it through months worth of testing, measuring the degradation) and then extrapolating that over the lifetime. They then guarantee an MTBF figure and if you get a batch of their LED's on average, they will last more than x amount of hours. But they could last more, the MTBF figure is only a lower bound.
answered 47 mins ago
laptop2d
22.2k123175
answered 47 mins ago
laptop2d
22.2k123175
answered 47 mins ago
laptop2d
22.2k123175
answered 47 mins ago
laptop2d
22.2k123175
22.2k123175
add a comment |Â
add a comment |Â
up vote
0
down vote
Those times are rated lifetimes and can be very conservative. So it might well be that most or (in case you are lucky) some of them can handle a factor times more, so 15 years sounds not unreasonable.
answered 54 mins ago
Michel Keijzers
5,22862357
add a comment |Â
up vote
0
down vote
Those times are rated lifetimes and can be very conservative. So it might well be that most or (in case you are lucky) some of them can handle a factor times more, so 15 years sounds not unreasonable.
answered 54 mins ago
Michel Keijzers
5,22862357
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Those times are rated lifetimes and can be very conservative. So it might well be that most or (in case you are lucky) some of them can handle a factor times more, so 15 years sounds not unreasonable.
answered 54 mins ago
Michel Keijzers
5,22862357
Those times are rated lifetimes and can be very conservative. So it might well be that most or (in case you are lucky) some of them can handle a factor times more, so 15 years sounds not unreasonable.
answered 54 mins ago
Michel Keijzers
5,22862357
answered 54 mins ago
Michel Keijzers
5,22862357
answered 54 mins ago
Michel Keijzers
5,22862357
answered 54 mins ago
Michel Keijzers
5,22862357
5,22862357
add a comment |Â
add a comment |Â
up vote
0
down vote
Estimations of life expectancy of electronic components is a tricky business. As one can imagine, manufacturer can't wait 50,000 hours (or something like 2,290,000,000 hours for a RS232 receiver, see page 7 of this essay) to collect statistics of device failures, market doesn't allow this. All estimations are done using "accelerated models".
The idea is to set a batch of devices under extreme conditions (voltage, current, temperature, environmental factors) until some devices fail in a reasonable test time (days or hours), assuming no shift in failure mechanisms. Then, using some theoretical models of failure mechanisms and other ASSUMPTIONS, the failure rate gets extrapolated to normal operating conditions. Usually the theoretical models are of exponential type, so small errors during accelerated testing can result in vast differences in estimations for tails of these exponential functions. So the models are usually on a conservative side, to avoid liabilities from catastrophic premature failures.
For example, if the accelerated model for a LED did include the air humidity and rust/oxidation factor, but your LED was always at room and dry air conditions, it can last much-much longer than the manufacturer's specified MTBF.
answered 9 mins ago
Ale..chenski
24.4k11857
add a comment |Â
up vote
0
down vote
Estimations of life expectancy of electronic components is a tricky business. As one can imagine, manufacturer can't wait 50,000 hours (or something like 2,290,000,000 hours for a RS232 receiver, see page 7 of this essay) to collect statistics of device failures, market doesn't allow this. All estimations are done using "accelerated models".
The idea is to set a batch of devices under extreme conditions (voltage, current, temperature, environmental factors) until some devices fail in a reasonable test time (days or hours), assuming no shift in failure mechanisms. Then, using some theoretical models of failure mechanisms and other ASSUMPTIONS, the failure rate gets extrapolated to normal operating conditions. Usually the theoretical models are of exponential type, so small errors during accelerated testing can result in vast differences in estimations for tails of these exponential functions. So the models are usually on a conservative side, to avoid liabilities from catastrophic premature failures.
For example, if the accelerated model for a LED did include the air humidity and rust/oxidation factor, but your LED was always at room and dry air conditions, it can last much-much longer than the manufacturer's specified MTBF.
answered 9 mins ago
Ale..chenski
24.4k11857
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Estimations of life expectancy of electronic components is a tricky business. As one can imagine, manufacturer can't wait 50,000 hours (or something like 2,290,000,000 hours for a RS232 receiver, see page 7 of this essay) to collect statistics of device failures, market doesn't allow this. All estimations are done using "accelerated models".
The idea is to set a batch of devices under extreme conditions (voltage, current, temperature, environmental factors) until some devices fail in a reasonable test time (days or hours), assuming no shift in failure mechanisms. Then, using some theoretical models of failure mechanisms and other ASSUMPTIONS, the failure rate gets extrapolated to normal operating conditions. Usually the theoretical models are of exponential type, so small errors during accelerated testing can result in vast differences in estimations for tails of these exponential functions. So the models are usually on a conservative side, to avoid liabilities from catastrophic premature failures.
For example, if the accelerated model for a LED did include the air humidity and rust/oxidation factor, but your LED was always at room and dry air conditions, it can last much-much longer than the manufacturer's specified MTBF.
answered 9 mins ago
Ale..chenski
24.4k11857
Estimations of life expectancy of electronic components is a tricky business. As one can imagine, manufacturer can't wait 50,000 hours (or something like 2,290,000,000 hours for a RS232 receiver, see page 7 of this essay) to collect statistics of device failures, market doesn't allow this. All estimations are done using "accelerated models".
The idea is to set a batch of devices under extreme conditions (voltage, current, temperature, environmental factors) until some devices fail in a reasonable test time (days or hours), assuming no shift in failure mechanisms. Then, using some theoretical models of failure mechanisms and other ASSUMPTIONS, the failure rate gets extrapolated to normal operating conditions. Usually the theoretical models are of exponential type, so small errors during accelerated testing can result in vast differences in estimations for tails of these exponential functions. So the models are usually on a conservative side, to avoid liabilities from catastrophic premature failures.
For example, if the accelerated model for a LED did include the air humidity and rust/oxidation factor, but your LED was always at room and dry air conditions, it can last much-much longer than the manufacturer's specified MTBF.
answered 9 mins ago
Ale..chenski
24.4k11857
answered 9 mins ago
Ale..chenski
24.4k11857
answered 9 mins ago
Ale..chenski
24.4k11857
answered 9 mins ago
Ale..chenski
24.4k11857
24.4k11857
add a comment |Â
add a comment |Â
Barmar is a new contributor. Be nice, and check out our Code of Conduct.
Barmar is a new contributor. Be nice, and check out our Code of Conduct.
Barmar is a new contributor. Be nice, and check out our Code of Conduct.
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