Copy of LED Driver with Auto-Dimming for Thermal Protection - on Thu, 01/30/2020 - 18:30 Designer https://explore.partquest.com/node/279833 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/279833"></iframe> Title Description <p>This LED lighting example demonstrates the value of simulating both the electrical and thermal* aspects of power dissipating circuits together, simultaneously.</p><p>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.</p><p>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.</p><p>----------------</p><p>* 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.</p> About text formats Tags 555 Timercurrent mirrorPWMLEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
LED Driver with Auto-Dimming for Thermal Protection (with realistic thermal time constants) Designer https://explore.partquest.com/node/277479 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/277479"></iframe> Title Description <p>This LED lighting example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.</p><p>In this application example, a Vishay NTCS0402 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.</p><p>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 sets 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.</p><p>*Note: The PWM switching frequency was intentionally reduced from the practical value of 260 Hz to 2.6 Hz, in order to provide fast simulations and realistic (long) thermal time constants. This was accomplished by increasing the 555 timer capacitor from 100 nF to 10 uF. This should have no significant impact on the thermal feedback or settling behavior that would be observed at the higher PWM frequencies needed to avoid visual "flicker" to the human eye (i.e. > 200 Hz).</p> About text formats Tags 555 Timercurrent mirrorPWMLEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
LED Driver with Auto-Dimming - Low PWM frequency but realistic thermal time constants Designer https://explore.partquest.com/node/277264 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/277264"></iframe> Title Description <p>This LED lighting example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.</p><p>In this application example, a Vishay NTCS0402 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.</p><p>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 sets 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.</p><p>*Note: The PWM switching frequency was intentionally reduced from the practical value of 260 Hz (used in the companion design https://www.systemvision.com/design/led-driver-auto-dimming-thermal-protection), to 2.6 Hz, in order to provide fast simulations and realistic (long) thermal time constants. This was accomplished by increasing the 555 timer capacitor from 100 nF to 10 uF. This should have no significant impact on the thermal feedback or settling behavior that would be observed at the higher PWM frequencies needed to avoid visual "flicker" to the human eye (i.e. > 200 Hz).</p> About text formats Tags 555 Timercurrent mirrorPWMLEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
LED Driver with Auto-Dimming for Thermal Protection Designer https://explore.partquest.com/node/275457 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/275457"></iframe> Title Description <p>This LED lighting example demonstrates the value of simulating both the electrical and thermal* aspects of power dissipating circuits together, simultaneously.</p><p>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.</p><p>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.</p><p>----------------</p><p>* 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.</p> About text formats Tags 555 Timercurrent mirrorPWMLEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
LED Driver with Auto-Dimming for Thermal Protection- Alain Designer https://explore.partquest.com/node/275433 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/275433"></iframe> Title Description <p>This LED lighting example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.</p> <p>In this application example, a Vishay NTCS0603E3103MT 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.</p> <p>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.</p> About text formats Tags 555 Timercurrent mirrorPWMLEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
Laser Temperature Regulator using Peltier TEC and Vishay Thermistor Designer https://explore.partquest.com/node/270478 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/270478"></iframe> Title Description <p>This "Live Application" example shows the ability of a Peltier Module, or Thermo-Electric Cooler (TEC), to actively transfer heat away from a "laser" or other electronic device, during fast-changing power dissipation conditions. A Vishay thermistor from our Partner Library, with resistance that is sensitive to temperature, is used in a Wheatstone Bridge configuration. It produces a differential voltage that is amplified by an op-amp circuit. The op-amp output voltage is approximately proportional to temperature.</p><p>The rest of the control loop is modeled here using ideal mathematical control blocks. This abstraction allows the designer to focus on the overall performance of the regulator, and to assess the choice of PID gains during actual transient operation.</p><p>All of the parameters in blue can be changed by the user and a new simulation run. The updated scope waveform results will show the effect of that change. You can change the electrical resistance of the "laser", which is just a simple resistance heating element for this example, to change the power dissipation level. You can also change the heat transfer resistance values in the thermal network, to see their effect on system performance. Finally, you can change the PID control block gains and see the effect on the steady-state and transient behavior of this temperature regulation system.</p><p>Note: You can move the waveform probes to see any other signal in the system.</p> About text formats Tags TECPeltierThermistorPIDVIshay NTC thermistor Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
Simple test circuit to test PTCEL 9 Designer https://explore.partquest.com/node/259603 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/259603"></iframe> Title Description <p>Simple test circuit for PTCEL13R501 where rising voltages are applied in time . </p> About text formats Tags VISHAYPTCELPTCThermistor Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
simple test of Vishay's NTC/RTD's with current source testing Designer https://explore.partquest.com/node/259452 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/259452"></iframe> Title Description <p>the application of a minimal current on all the devices allows for measuring the resistance value all along the temperature range. The measured resistance quantity"rntc" or "rpts" or "rtfpt" of the "therm1" entity can be compared to the R-T curve of the data sheet.</p> About text formats Tags VISHAYNTCThermistorRTDPTSTFPT Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
simple test of PTCEL under voltage and different starting states 4 Designer https://explore.partquest.com/node/259312 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/259312"></iframe> Title Description <p>This file presents a simple test circuit in order to verify the functionality of the PTCEL models. The component is tested under voltage, first a value with no tripping and then tripping.</p><p>The left part has an initialized temperature at ambient (25°C) and the right is already in the steady state temperature corresponding to initial voltage and ambient temperature. The component PTCEL17R501 is here first tested at a non trip current at 50 mA , and then trips at a current of 95 mA, and comes back to the state where the current is limited to 50 mA. A further increase of the supply voltage will send the parts at even higher temperature.</p> About text formats Tags VISHAYPTCPTCELThermistor Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
simple test of PTCEL under voltage and different starting states 2 Designer https://explore.partquest.com/node/259307 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/259307"></iframe> Title Description <p>This file presents a simple test circuit in order to verify the functionality of the PTCEL models. The component is tested under voltage, first a value with no tripping and then tripping.</p><p>The left part has an initialized temperature at ambient (25°C) and the right is already in the steady state temperature corresponding to initial voltage and ambient temperature. The component PTCEL13R600 is here first tested at a non trip current at 120 mA , and then trips at a current of 200 mA, and comes back to the state where the current is limited to 130 mA. A further increase of the supply voltage will send the parts at even higher temperature.</p> About text formats Tags VISHAYPTCPTCELThermistor Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
