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Description

This LED lighting example demonstrates the value of simulating both the electrical and thermal* aspects of power dissipating circuits together, simultaneously.

In this application example, a Vishay NTCS0603 Thermistor provides feedback of the enclosure temperature. This feedback is used to control PWM dimming of the LEDs, thereby limiting the internal temperature when operating at high external ambient temperature conditions.

This is a "Live" design, the user can change key parameter values and then run new simulations to see the results. These parameters include "r_mirror", the resistance of the current mirror that controls the capacitor charging rate of the 555 timer, and thereby set the PWM frequency. The user can also change "r_offset" that controls the temperature level at which the dimming operation begins. Finally, the user can set "r_iLED_set", to control the ON-state operating current of the LEDs.

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* To reduce the time needed to simulate the transition and settling at 6 different temperature levels, all thermal time constants were reduced by approximately 1000x. The actual thermal response time constant of the NTCS0603 is approximately 3 seconds (depends on mounting), not 3 msec! Also, the enclosure thermal capacitance value would more likely be 3 (J/degC) instead of 3 (mJ/degC), giving a thermal time constant for the enclosure of 10 (degC/Watt) * 3 (J/degC) = 30 seconds. This time scaling does not affect the static relationship between the outside temperature and PWM dimming.

tunable example 2

bedrosian1134
Designer198997

bedrosian1134

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5 years 10 months

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Description

This LED lighting example demonstrates the value of simulating both the electrical and thermal* aspects of power dissipating circuits together, simultaneously.

In this application example, a Vishay NTCS0603 Thermistor provides feedback of the enclosure temperature. This feedback is used to control PWM dimming of the LEDs, thereby limiting the internal temperature when operating at high external ambient temperature conditions.

This is a "Live" design, the user can change key parameter values and then run new simulations to see the results. These parameters include "r_mirror", the resistance of the current mirror that controls the capacitor charging rate of the 555 timer, and thereby set the PWM frequency. The user can also change "r_offset" that controls the temperature level at which the dimming operation begins. Finally, the user can set "r_iLED_set", to control the ON-state operating current of the LEDs.

----------------

* To reduce the time needed to simulate the transition and settling at 6 different temperature levels, all thermal time constants were reduced by approximately 1000x. The actual thermal response time constant of the NTCS0603 is approximately 3 seconds (depends on mounting), not 3 msec! Also, the enclosure thermal capacitance value would more likely be 3 (J/degC) instead of 3 (mJ/degC), giving a thermal time constant for the enclosure of 10 (degC/Watt) * 3 (J/degC) = 30 seconds. This time scaling does not affect the static relationship between the outside temperature and PWM dimming.

TEST TUNABLE Analog LED Driver with Thermal Protection using FloTHERM Netlist

Galina
Designer21

Galina

Member for

10 years 5 months

104

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3

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Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

Copy of SEMI-THERM 37 BCI ROM for LED Spotlight - on Fri, 02/05/2021 - 12:36

noguchi.yusuke
Designer229298

noguchi.yusuke

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4 years 2 months

23

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Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

Thermal dynamics models were automatically generated from a full 3D-CFD analysis using FloTHERM. This includes a thermal netlist model for the spotlight board layout and enclosure, as well as a BCI ROM model for MOSFET QFN package thermals. The format of both models is IEEE Standard VHDL-AMS, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

Colin_Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Wed, 12/16/2020 - 20:27

colin_zhou
Designer236981

colin_zhou

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3 years 4 months

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Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

Copy of Colin Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Mon, 12/14/2020 - 19:02

colin_zhou
Designer236981

colin_zhou

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3 years 4 months

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Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

Colin Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Mon, 12/14/2020 - 17:42

colin_zhou
Designer236981

colin_zhou

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3 years 4 months

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Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

Copy of Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Sun, 12/13/2020 - 00:29

colin_zhou
Designer236981

colin_zhou

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3 years 4 months

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Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

Copy of Not tunable Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Fri, 12/11/2020 - 23:45

colin_zhou
Designer236981

colin_zhou

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3 years 4 months

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Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.

Copy of Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Thu, 11/19/2020 - 17:33

seya.o
Designer113006

seya.o

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7 years 1 month

82

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3

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Description

This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.

In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.

The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.