electro-thermal | PartQuest™ Explore

Application Area

Electronics Cooling and Thermal Control

Copy of Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Fri, 11/08/2024 - 14:38

Designer240663

Member for

4 years

22

designs

2

groups

Member of the PartQuest Explore team.

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.

About text formats

Copy of Modeling Transistor Amplifier Self-Heating - Thermal Network - on Thu, 08/08/2024 - 11:54

Designer257738

Member for

10 months 4 weeks

4

designs

1

groups

Welcome to the community!!

Description

This example shows the importance of modeling thermal interaction effects, or "thermal crosstalk", in power dissipating circuits. The "design" is a simple transistor amplifier, using just an 8 Ohm pull-up resistor and an active pull-down NPN BJT. Both of these models are from our "Thermal and Electro-thermal" Components Library, so they have a thermal port that can connect to an external thermal network. These models output all power dissipated in the device as a thermal heat-flow into that network.

The thermal network includes the heat-sink's heat capacitance (0.1 J/degC) and heat transfer resistance to the ambient (10 degC/Watt). This assumes the resistor and transistor contribute heat to the same heat-sink. The transistor's thermal heat-flow path also includes an 8.8 degC/Watt resistance, to represent the Junction-to-Lead Thermal Resistance as published in the device datasheet (Diodes Inc. FZT869).

From the simulation results it is clear that the heat-sink temperature rises to nearly 120 degC (purple waveform), causing the transistor's junction temperature to approach 150 degC (average, red waveform). This is significantly higher than the value predicted in the companion design example: "Modeling Transistor Amplifier Self-Heating - Hot Part Monitor", which assumed the two devices were thermally isolated.

About text formats

Copy of Modeling Transistor Amplifier Self-Heating - Thermal Network - on Mon, 07/22/2024 - 11:06

Designer257481

Member for

11 months 2 weeks

9

designs

1

groups

Welcome to the community!!

Description

This example shows the importance of modeling thermal interaction effects, or "thermal crosstalk", in power dissipating circuits. The "design" is a simple transistor amplifier, using just an 8 Ohm pull-up resistor and an active pull-down NPN BJT. Both of these models are from our "Thermal and Electro-thermal" Components Library, so they have a thermal port that can connect to an external thermal network. These models output all power dissipated in the device as a thermal heat-flow into that network.

The thermal network includes the heat-sink's heat capacitance (0.1 J/degC) and heat transfer resistance to the ambient (10 degC/Watt). This assumes the resistor and transistor contribute heat to the same heat-sink. The transistor's thermal heat-flow path also includes an 8.8 degC/Watt resistance, to represent the Junction-to-Lead Thermal Resistance as published in the device datasheet (Diodes Inc. FZT869).

From the simulation results it is clear that the heat-sink temperature rises to nearly 120 degC (purple waveform), causing the transistor's junction temperature to approach 150 degC (average, red waveform). This is significantly higher than the value predicted in the companion design example: "Modeling Transistor Amplifier Self-Heating - Hot Part Monitor", which assumed the two devices were thermally isolated.

About text formats

Copy of Electro-thermal Trade-off Analysis for AC-DC Converter with Current Boost Regulator - on Wed, 04/17/2024 - 16:33

Designer255846

Member for

1 year 2 months

1

designs

1

groups

Welcome to the community!!

Description

This example shows the capability of modeling the electrothermal aspects of power dissipating circuits. The design is a 5V regulator (non-switching), driven from a 120 Vac/60 Hz input and using a transformer/rectifier circuit to step down to a much lower DC-link voltage.

The load current capability is 5A, which is well above the current limit of the linear regular component itself. This is thanks to the load sharing role of the bypass PNP transistor. The design is based on an example application circuit shown in Figure 11 of the On Semiconductor Datasheet MC7800/D, November 2014 - Rev. 27.

All of the power dissipating electronics' models are from the "Thermal and Electro-thermal" Components Library. They have a thermal port that connects to the thermal network (i.e. red wires). These models output all the power dissipated in the device as a thermal heat-flow into that network. This includes the rectifier diodes, the linear regulator and the BJT, as well as the current sense resistor and the effective winding resistances of the transformer primary and secondary.

The thermal network includes the heat-sink's heat capacitance (0.1 J/degC) and heat transfer resistance to the ambient (1 degC/Watt), as well as the datasheet published values for the junction-to-lead thermal resistances of all the active electronic components. An assumed value for the thermal capacitance of the BJT (0.005 J/degC, not provided by the manufacturer) was added for purposes of illustration. Obtaining the actual value would require deeper analysis or measurement of this important component characteristic. However, in this example, both thermal capacitance values were selected solely to give sufficiently fast thermal time constants, so that steady-state operating temperatures could be reached with minimal simulation time.

This design is based on another shared design:

"https://www.systemvision.com/design/ac-dc-power-adapter-current-boost-regulator", That design has been modified not only to add the electrothermal aspects, but it was also adjusted to improve its observed thermal performance. For example, the DC-link capacitance (c3) was increased from 4700uF to 22000uF, to allow a reduced DC-link operating voltage (i.e. to improve efficiency) while avoiding regulation drop-out at AC zero-crossings under heavy load conditions.

About text formats

Copy of Linear Regulator Temperature Finder - on Sat, 02/17/2024 - 10:29

Designer254184

Member for

1 year 4 months

0

designs

1

groups

Welcome to the community!!

Description

This "virtual test circuit" can help designers predict the temperatures of a linear regulator, based on readily available information from the manufacturer's datasheet. Users can simply make a copy of this circuit, then adjust the regulator model's parameters to match the electrical and thermal characteristics for their particular part.

These parameters include the output voltage, VDO and current limit, as well as the junction-to-case and junction-to-ambient or heat-sink thermal resistance values. In this example, an L78S05 with direct case to ambient heat transfer is modeled (i.e. no heat-sink). The datasheet specifies the junction-to-case resistance is 5degC/Watt, and the junction-to-ambient resistance for a T0-220 package is 50 degC/Watt. Therefore, the difference of 45 degC/Watt is assumed to be the case-to-ambient thermal resistance. This value is assigned as the "heat-sink" resistance.

If an actual heat sink is being used, its published thermal resistance would be used instead. If the heat sink heat capacitance is also provided, that value can be applied to the thermal capacitor, and then the simulation will predict not only the steady-state operating temperature, but also temperature transients.

The input voltage function generator can also be adjusted to apply any time-varying input voltage profile, and the test circuit will show the corresponding time-varying temperature profile. This can be used to identify peak as well as average operating temperatures.

The user can also change the load current level and/or the load type using any relevant models in the Component Library, or create custom load models.

About text formats

Copy of Linear Regulator Temperature Finder - on Sat, 02/17/2024 - 10:29

Designer254184

Member for

1 year 4 months

0

designs

1

groups

Welcome to the community!!

Description

This "virtual test circuit" can help designers predict the temperatures of a linear regulator, based on readily available information from the manufacturer's datasheet. Users can simply make a copy of this circuit, then adjust the regulator model's parameters to match the electrical and thermal characteristics for their particular part.

These parameters include the output voltage, VDO and current limit, as well as the junction-to-case and junction-to-ambient or heat-sink thermal resistance values. In this example, an L78S05 with direct case to ambient heat transfer is modeled (i.e. no heat-sink). The datasheet specifies the junction-to-case resistance is 5degC/Watt, and the junction-to-ambient resistance for a T0-220 package is 50 degC/Watt. Therefore, the difference of 45 degC/Watt is assumed to be the case-to-ambient thermal resistance. This value is assigned as the "heat-sink" resistance.

If an actual heat sink is being used, its published thermal resistance would be used instead. If the heat sink heat capacitance is also provided, that value can be applied to the thermal capacitor, and then the simulation will predict not only the steady-state operating temperature, but also temperature transients.

The input voltage function generator can also be adjusted to apply any time-varying input voltage profile, and the test circuit will show the corresponding time-varying temperature profile. This can be used to identify peak as well as average operating temperatures.

The user can also change the load current level and/or the load type using any relevant models in the Component Library, or create custom load models.

About text formats

Copy of Linear Regulator Temperature Finder - on Sat, 02/17/2024 - 10:29

Designer254184

Member for

1 year 4 months

0

designs

1

groups

Welcome to the community!!

Description

This "virtual test circuit" can help designers predict the temperatures of a linear regulator, based on readily available information from the manufacturer's datasheet. Users can simply make a copy of this circuit, then adjust the regulator model's parameters to match the electrical and thermal characteristics for their particular part.

These parameters include the output voltage, VDO and current limit, as well as the junction-to-case and junction-to-ambient or heat-sink thermal resistance values. In this example, an L78S05 with direct case to ambient heat transfer is modeled (i.e. no heat-sink). The datasheet specifies the junction-to-case resistance is 5degC/Watt, and the junction-to-ambient resistance for a T0-220 package is 50 degC/Watt. Therefore, the difference of 45 degC/Watt is assumed to be the case-to-ambient thermal resistance. This value is assigned as the "heat-sink" resistance.

If an actual heat sink is being used, its published thermal resistance would be used instead. If the heat sink heat capacitance is also provided, that value can be applied to the thermal capacitor, and then the simulation will predict not only the steady-state operating temperature, but also temperature transients.

The input voltage function generator can also be adjusted to apply any time-varying input voltage profile, and the test circuit will show the corresponding time-varying temperature profile. This can be used to identify peak as well as average operating temperatures.

The user can also change the load current level and/or the load type using any relevant models in the Component Library, or create custom load models.

About text formats

Copy of Linear Regulator Temperature Finder - on Sat, 02/17/2024 - 10:29

Designer254184

Member for

1 year 4 months

0

designs

1

groups

Welcome to the community!!

Description

This "virtual test circuit" can help designers predict the temperatures of a linear regulator, based on readily available information from the manufacturer's datasheet. Users can simply make a copy of this circuit, then adjust the regulator model's parameters to match the electrical and thermal characteristics for their particular part.

These parameters include the output voltage, VDO and current limit, as well as the junction-to-case and junction-to-ambient or heat-sink thermal resistance values. In this example, an L78S05 with direct case to ambient heat transfer is modeled (i.e. no heat-sink). The datasheet specifies the junction-to-case resistance is 5degC/Watt, and the junction-to-ambient resistance for a T0-220 package is 50 degC/Watt. Therefore, the difference of 45 degC/Watt is assumed to be the case-to-ambient thermal resistance. This value is assigned as the "heat-sink" resistance.

If an actual heat sink is being used, its published thermal resistance would be used instead. If the heat sink heat capacitance is also provided, that value can be applied to the thermal capacitor, and then the simulation will predict not only the steady-state operating temperature, but also temperature transients.

The input voltage function generator can also be adjusted to apply any time-varying input voltage profile, and the test circuit will show the corresponding time-varying temperature profile. This can be used to identify peak as well as average operating temperatures.

The user can also change the load current level and/or the load type using any relevant models in the Component Library, or create custom load models.

About text formats

Copy of Electro-thermal Trade-off Analysis for AC-DC Converter with Current Boost Regulator - on Sun, 01/14/2024 - 17:47

Designer253227

Member for

1 year 5 months

2

designs

1

groups

Welcome to the community!!

Description

This example shows the capability of modeling the electrothermal aspects of power dissipating circuits. The design is a 5V regulator (non-switching), driven from a 120 Vac/60 Hz input and using a transformer/rectifier circuit to step down to a much lower DC-link voltage.

The load current capability is 5A, which is well above the current limit of the linear regular component itself. This is thanks to the load sharing role of the bypass PNP transistor. The design is based on an example application circuit shown in Figure 11 of the On Semiconductor Datasheet MC7800/D, November 2014 - Rev. 27.

All of the power dissipating electronics' models are from the "Thermal and Electro-thermal" Components Library. They have a thermal port that connects to the thermal network (i.e. red wires). These models output all the power dissipated in the device as a thermal heat-flow into that network. This includes the rectifier diodes, the linear regulator and the BJT, as well as the current sense resistor and the effective winding resistances of the transformer primary and secondary.

The thermal network includes the heat-sink's heat capacitance (0.1 J/degC) and heat transfer resistance to the ambient (1 degC/Watt), as well as the datasheet published values for the junction-to-lead thermal resistances of all the active electronic components. An assumed value for the thermal capacitance of the BJT (0.005 J/degC, not provided by the manufacturer) was added for purposes of illustration. Obtaining the actual value would require deeper analysis or measurement of this important component characteristic. However, in this example, both thermal capacitance values were selected solely to give sufficiently fast thermal time constants, so that steady-state operating temperatures could be reached with minimal simulation time.

This design is based on another shared design:

"https://www.systemvision.com/design/ac-dc-power-adapter-current-boost-regulator", That design has been modified not only to add the electrothermal aspects, but it was also adjusted to improve its observed thermal performance. For example, the DC-link capacitance (c3) was increased from 4700uF to 22000uF, to allow a reduced DC-link operating voltage (i.e. to improve efficiency) while avoiding regulation drop-out at AC zero-crossings under heavy load conditions.

About text formats

Copy of Electro-thermal Trade-off Analysis for AC-DC Converter with Current Boost Regulator - on Sun, 01/14/2024 - 17:47

Designer253227

Member for

1 year 5 months

2

designs

1

groups

Welcome to the community!!

Description

This example shows the capability of modeling the electrothermal aspects of power dissipating circuits. The design is a 5V regulator (non-switching), driven from a 120 Vac/60 Hz input and using a transformer/rectifier circuit to step down to a much lower DC-link voltage.

The load current capability is 5A, which is well above the current limit of the linear regular component itself. This is thanks to the load sharing role of the bypass PNP transistor. The design is based on an example application circuit shown in Figure 11 of the On Semiconductor Datasheet MC7800/D, November 2014 - Rev. 27.

All of the power dissipating electronics' models are from the "Thermal and Electro-thermal" Components Library. They have a thermal port that connects to the thermal network (i.e. red wires). These models output all the power dissipated in the device as a thermal heat-flow into that network. This includes the rectifier diodes, the linear regulator and the BJT, as well as the current sense resistor and the effective winding resistances of the transformer primary and secondary.

The thermal network includes the heat-sink's heat capacitance (0.1 J/degC) and heat transfer resistance to the ambient (1 degC/Watt), as well as the datasheet published values for the junction-to-lead thermal resistances of all the active electronic components. An assumed value for the thermal capacitance of the BJT (0.005 J/degC, not provided by the manufacturer) was added for purposes of illustration. Obtaining the actual value would require deeper analysis or measurement of this important component characteristic. However, in this example, both thermal capacitance values were selected solely to give sufficiently fast thermal time constants, so that steady-state operating temperatures could be reached with minimal simulation time.

This design is based on another shared design:

"https://www.systemvision.com/design/ac-dc-power-adapter-current-boost-regulator", That design has been modified not only to add the electrothermal aspects, but it was also adjusted to improve its observed thermal performance. For example, the DC-link capacitance (c3) was increased from 4700uF to 22000uF, to allow a reduced DC-link operating voltage (i.e. to improve efficiency) while avoiding regulation drop-out at AC zero-crossings under heavy load conditions.

About text formats

Troubleshooting Terms of Use Cookie Notice Data Privacy Notice