Constant current regulators (CCRs) are self-biased circuits that provide constant current to LEDs over a wide range of input voltages and temperatures to ensure consistent brightness. CCRs offer advantages over resistor-based and linear/switching regulator solutions by improving efficiency and simplifying design while providing protection for LEDs. The document discusses CCR product offerings and design examples for driving single or multiple LED strings from various power sources.
1. Concept on drives
2. What is drives ?
3. How drive does ?
4. What is torque ?
5. What is Motor Torque ( Tm )?
6. What is Motor Speed?
7. Drive are two types
8. AC Drive
9. DC Drive
10. Pulse Width Modulation
11. Sinusoidal PWM
12. Components of ASTAT
13. What is DTC ?
14. Direct Torque Control
15. Control Display Panel
16. ABB ACS800 DRIVE FOR CRANE
1. Concept on drives
2. What is drives ?
3. How drive does ?
4. What is torque ?
5. What is Motor Torque ( Tm )?
6. What is Motor Speed?
7. Drive are two types
8. AC Drive
9. DC Drive
10. Pulse Width Modulation
11. Sinusoidal PWM
12. Components of ASTAT
13. What is DTC ?
14. Direct Torque Control
15. Control Display Panel
16. ABB ACS800 DRIVE FOR CRANE
Automatic generation control (AGC) is a system for adjusting the power output of multiple generators at different power plants, in response to changes in the load. Since a power grid requires that generation and load closely balance moment by moment, frequent adjustments to the output of generators are necessary. The balance can be judged by measuring the system frequency; if it is increasing, more power is being generated than used, which causes all the machines in the system to accelerate. If the system frequency is decreasing, more load is on the system than the instantaneous generation can provide, which causes all generators to slow down.
Power factor improvement is the essence of any power sector for realible operations. This report provides literature study of a fixed capacitor thyristor controlled reactor type of power factor compensator by matlab simulation and implementation in programmed microcontroller. To retaining power factor closed to unity under various load condition the arduino ATmega8 microcontroller is used which is programmed by keil software. The simulation is done using proteus software which display power factor according to the variation in load whenever a capacitive load is connected to the transmission line, a shunt reactor is connected which injects lagging reactive VARs to the power system. This report also includes the matlab simulation for three phase power factor improvement by using fixed capacitor thyristor controlled reactor. As a
result the power factor is improved. The results given in this report provides
suitable matlab simulation and proteus simulation based reactor power compensation and power factor improvement and techniques using a FCTCR.
These slides are all about Phasor Measurement Units (PMUs). An introduction to PMU is presented as a preliminary knowledge for the course 'Distribution Generation and Smart Grid'. Your valuable suggestions are welcome.
Part of Lecture series on EEE-413, Electrical Drives (DC Drives) delivered by me to students of VIII Semester B.E. (Electrical), Session 2018-19.
Z. H. College of Engg. & Technology, Aligarh Muslim University, Aligarh.
Missing materials will be uploaded shortly.
Please comment and feel free to ask anything related. Thanks!
Automatic generation control (AGC) is a system for adjusting the power output of multiple generators at different power plants, in response to changes in the load. Since a power grid requires that generation and load closely balance moment by moment, frequent adjustments to the output of generators are necessary. The balance can be judged by measuring the system frequency; if it is increasing, more power is being generated than used, which causes all the machines in the system to accelerate. If the system frequency is decreasing, more load is on the system than the instantaneous generation can provide, which causes all generators to slow down.
Power factor improvement is the essence of any power sector for realible operations. This report provides literature study of a fixed capacitor thyristor controlled reactor type of power factor compensator by matlab simulation and implementation in programmed microcontroller. To retaining power factor closed to unity under various load condition the arduino ATmega8 microcontroller is used which is programmed by keil software. The simulation is done using proteus software which display power factor according to the variation in load whenever a capacitive load is connected to the transmission line, a shunt reactor is connected which injects lagging reactive VARs to the power system. This report also includes the matlab simulation for three phase power factor improvement by using fixed capacitor thyristor controlled reactor. As a
result the power factor is improved. The results given in this report provides
suitable matlab simulation and proteus simulation based reactor power compensation and power factor improvement and techniques using a FCTCR.
These slides are all about Phasor Measurement Units (PMUs). An introduction to PMU is presented as a preliminary knowledge for the course 'Distribution Generation and Smart Grid'. Your valuable suggestions are welcome.
Part of Lecture series on EEE-413, Electrical Drives (DC Drives) delivered by me to students of VIII Semester B.E. (Electrical), Session 2018-19.
Z. H. College of Engg. & Technology, Aligarh Muslim University, Aligarh.
Missing materials will be uploaded shortly.
Please comment and feel free to ask anything related. Thanks!
Presentation on Over-/under-voltage protection of electrical applianceNishant Kumar
Sudden fluctuation in supply is a very big problem in industries and domestic applications. It causes a major loss for industries, offices and homes.
This project gives a low cost and powerful solution for this problem. This Circuit protects refrigerators ,ACs, Microwave ovens as well as other appliances from over and under voltage fluctuations.
Original Power Supply IC LNK626PG LNK626P LNK626 DIP-7 New Power IntegrationAUTHELECTRONIC
Original Power Supply IC LNK626PG LNK626P LNK626 DIP-7 New Power Integration
https://authelectronic.com/original-power-ic-lnk626pg-lnk626p-lnk626-dip-7-new-power-integration
Summary
1. ON Semiconductor has solutions for all low power offline driver topologies: Flyback, Buck-Boost, Buck-Boost, Linear
2. Primary Side Control approach optimized for tight accuracy and wide Vf support for high production yield and reduced development time
3. General shift in market to address non-isolated topologies
Pre Final Year project/ mini project for Electronics and communication engine...Shirshendu Das
Mini project for Electronics and communication engineering (ECE) to build an AC to DC power supply using Full Wave Rectifier having input as 220-240V AC and giving stable filtered output of 5V, -5V & variable 5V DC. Simulation of the circuit was done in Proteus design suite.
zkStudyClub - Reef: Fast Succinct Non-Interactive Zero-Knowledge Regex ProofsAlex Pruden
This paper presents Reef, a system for generating publicly verifiable succinct non-interactive zero-knowledge proofs that a committed document matches or does not match a regular expression. We describe applications such as proving the strength of passwords, the provenance of email despite redactions, the validity of oblivious DNS queries, and the existence of mutations in DNA. Reef supports the Perl Compatible Regular Expression syntax, including wildcards, alternation, ranges, capture groups, Kleene star, negations, and lookarounds. Reef introduces a new type of automata, Skipping Alternating Finite Automata (SAFA), that skips irrelevant parts of a document when producing proofs without undermining soundness, and instantiates SAFA with a lookup argument. Our experimental evaluation confirms that Reef can generate proofs for documents with 32M characters; the proofs are small and cheap to verify (under a second).
Paper: https://eprint.iacr.org/2023/1886
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Welcome to the first live UiPath Community Day Dubai! Join us for this unique occasion to meet our local and global UiPath Community and leaders. You will get a full view of the MEA region's automation landscape and the AI Powered automation technology capabilities of UiPath. Also, hosted by our local partners Marc Ellis, you will enjoy a half-day packed with industry insights and automation peers networking.
📕 Curious on our agenda? Wait no more!
10:00 Welcome note - UiPath Community in Dubai
Lovely Sinha, UiPath Community Chapter Leader, UiPath MVPx3, Hyper-automation Consultant, First Abu Dhabi Bank
10:20 A UiPath cross-region MEA overview
Ashraf El Zarka, VP and Managing Director MEA, UiPath
10:35: Customer Success Journey
Deepthi Deepak, Head of Intelligent Automation CoE, First Abu Dhabi Bank
11:15 The UiPath approach to GenAI with our three principles: improve accuracy, supercharge productivity, and automate more
Boris Krumrey, Global VP, Automation Innovation, UiPath
12:15 To discover how Marc Ellis leverages tech-driven solutions in recruitment and managed services.
Brendan Lingam, Director of Sales and Business Development, Marc Ellis
In his public lecture, Christian Timmerer provides insights into the fascinating history of video streaming, starting from its humble beginnings before YouTube to the groundbreaking technologies that now dominate platforms like Netflix and ORF ON. Timmerer also presents provocative contributions of his own that have significantly influenced the industry. He concludes by looking at future challenges and invites the audience to join in a discussion.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Le nuove frontiere dell'AI nell'RPA con UiPath Autopilot™UiPathCommunity
In questo evento online gratuito, organizzato dalla Community Italiana di UiPath, potrai esplorare le nuove funzionalità di Autopilot, il tool che integra l'Intelligenza Artificiale nei processi di sviluppo e utilizzo delle Automazioni.
📕 Vedremo insieme alcuni esempi dell'utilizzo di Autopilot in diversi tool della Suite UiPath:
Autopilot per Studio Web
Autopilot per Studio
Autopilot per Apps
Clipboard AI
GenAI applicata alla Document Understanding
👨🏫👨💻 Speakers:
Stefano Negro, UiPath MVPx3, RPA Tech Lead @ BSP Consultant
Flavio Martinelli, UiPath MVP 2023, Technical Account Manager @UiPath
Andrei Tasca, RPA Solutions Team Lead @NTT Data
SAP Sapphire 2024 - ASUG301 building better apps with SAP Fiori.pdfPeter Spielvogel
Building better applications for business users with SAP Fiori.
• What is SAP Fiori and why it matters to you
• How a better user experience drives measurable business benefits
• How to get started with SAP Fiori today
• How SAP Fiori elements accelerates application development
• How SAP Build Code includes SAP Fiori tools and other generative artificial intelligence capabilities
• How SAP Fiori paves the way for using AI in SAP apps
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
9. CCR Low Turn On Voltage V / I plot crosses through zero The CCR turns on fast immediatedly the voltage goes positive With 0.5V input the current is already at 5mA - 25% ON
13. CCRs from ON Semiconductor Parameters NSI450XXT1G SOD-123 (2-terminal) NSI450XXZT1G SOT-223 (2-Terminal) NSI500XXDZT1G SOT-223 (3-Terminal) NSI500XXDDT1G D-PAK (2-Terminal) Max Anode to Cathode Voltage (V AK ) 45V 45V 50V 50V Voltage Overhead 1.8 V 1.8 V 1.8 V 1.8 V Constant Current Ireg @ Vak = 7.5V 10, 20, 25 & 30 mA 25 & 30 mA 20 - 40 mA ADJ 35 - 70 mA ADJ 60 – 100 mA ADJ 90 – 160 mA ADJ Current Tolerance over Voltage ± 15%, ±10% ± 15%, ±10% ± 15%, ±10% ± 15%, ±10% Ambient Operating Temp Range -55 to 85 o C -55 to 85 o C -55 to 85 o C -55 to 85 o C Max Junction Temperature 150 o C 150 o C 150 o C 150 o C Power Dissipation ( 25 o C; 500mm 2 ) 463 mW 1389 mW 1389 mW 2400 mW Power Dissipation ( 85 o C; 500mm 2 ) 230 mW 750 mW 750 mW 1270 mW ESD Rating: HBM – 1C > 1kV > 1kV > 2kV > 2kV
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17. Example of CCR Circuits 4 SW1 close – LED Dim Vibrator runs at 50% duty cycle SW2 close – LED Full Vibrator stops Select RC constant for 5 mS Dimming with external BJT Vibrator 2V 2V 2V 2V 2V 2V 2V 2V 2V SW2 SW1
18. Direct A/C Line LED circuit with CCR A/C 110 V RMS 3.52V 3.52V 3.52V 3.52V 3.52V 3.52V 30 LEDs 25 mA 100 Ω TP 1 TP 2 Current Loop TP 1 - 156 V P-P TP2 - LEDs 108 V, 52% On Current probe 25 mA
19. Direct A/C Line LED circuit with CCR -10% +10% 110 V RMS, TP1 - 156 V P-P TP2 - LEDs 108 V, 52% On Current probe 25 mA 100 V RMS, TP1 - 142 V P-P TP2 - LEDs 108 V, 47% On Current probe 25 mA 120 V RMS, TP1 - 170 V P-P TP2 - LEDs 108 V, 56% On Current probe 25 mA
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Editor's Notes
This is an introduction for On Semi Constant Current Regulator for Driving LEDs.
Welcome to the training module on Constant Current Regulator for Driving LEDs. This training module will introduce On semicoductor’s Constant Current Regulators and its applications.
LEDs have been used as indicators for many years. Only recently has the efficiency of LEDs been refined. This allows them to become the major source of lighting in many different markets. LEDs have certain characteristics that need to be considered when using them. LEDs are still a diode. Once the voltage across them is greater than the turn on voltage, they turn on very fast. LEDs have a negative forward voltage to temperature coefficient. Reviewing a simple LED circuit with resistors, the LED warms up and forward voltage across LEDs reduces. The reduction of the voltage across LEDs results an increase of voltage across the resistor. The current through the resistor and LEDs increases resulting in more power being dissipated and LED temperature increasing. That leads to the potential for thermal runaway.
LEDs have a negative light output to temperature coefficient. The warmer LEDs get, the less light it emits. LEDs also change color based on the temperature and current through them.
To obtain the longest life and highest reliability it is very desirable to drive LEDs with a constant current and keep the temperature as stable as possible. The main function of an LED driver is to limit the current regardless of input and output conditions across a range of operating conditions. AC-DC power conversion and driver regulation can be merged together into a single driver or separated into two stages.
LED drive circuits vary from being very simple to being very complicated. The most complex one is the switching regulator. It is the most efficiency but is often the most complex, expensive and has potential for EMI. Linear regulators, constant voltage or constant current, have some features of switching regulators but they are less efficient, do not have EMI issue and cost less than switching regulators. At the bottom end is the current limiting resistors. Obviously they have lowest cost and no EMI issues but they only provide regulation if the input voltage is regulated.
The constant current regulator or CCR is a small step up from the resistor circuit. It offers a simpler and lower cost solution compared to linear and switching regulators with significant improvement of performance compare to resistor circuits.
CCRs are self biased transistors and can be 2 or 3 terminal devices. The 2 terminal devices are designed and built to provide a specific current, i.e. 30 mA. The 3 terminal devices are adjustable across a small current range by chaning a bias resistor, i.e. 35 mA – 70 mA. The higher the bias resistor, the lower the current.
These curve traces were taken from 20mA CCR. The top left trace shows if the input voltage goes to negative, the CCR will break down at about -0.5 V. The circuit may need a reverse protection diode. As the input voltage goes positive, the CCR turns on very fast, often as soon as the voltage crossed the zero intersect point. The bottom right trace shows that at 0.5V input voltage, the CCR is already at 25% of the regulating current.
The CCR can handle high voltage surges. The scope trace was taken from CCR circuit with three LEDs operating at 12 V. The voltage drop across all three LEDs is 6V ( the magenta scope trace). The 50V, 1ms pulse was injected (the yellow scope trace). The CCR blocked the high voltage surges, and completely absorbed additional power being injected by the 50V pulse. The 6V across the LEDs remained constant.
Comparing the CCR to a resistor bias circuit, the resistor bias circuit, in yellow, shows the LED turn on as soon as the forward voltage across the LED is achieved, and the current through the LEDs is then proportional to the voltage across the resistor. A low voltage gives a low current and a low light output. A high voltage gives a high current and a high light output. But high voltage on LEDs has potential to go into thermal runaway. The CCR bias circuit, in magenta, shows the LEDs will also turn on as soon as the forward voltage across the LED is reached. The current increases rapidly as the voltage increases and then stabilizes at the control current of 25 mA, and remains constant regardless of the voltage increasing. The CCR enables brighter LEDs at low voltages. The LEDs have constant current over a wide voltage range. The LEDs are also protected as the voltage continues to rise.
Let’s look at how the CCR changes over temperature. The CCR is a very simple and does not have temperature compensation. It has a negative regulating current to temperature coefficient. The graph on the left is for a 20 mA CCR in a SOD-123 package. At an ambient temperature of +25 º C the current is being regulated at 20 mA. At an ambient temperature of -40 º C the regulating current is approximately 23 mA. At an ambient temperature of +85 º C the regulating current drops to approximately 17 mA. The graph on the right is for a 30 mA device in a SOT-223 package. This graph shows a similar change in regulating current to ambient temperature. As the ambient temperature increases the regulating current decreases. The larger SOT-223 is more thermally efficient compared to the SOD-123 package and thus has improved regulation. The negative temperature coefficient of the CCR protects LEDs as temperature and voltage increases.
ON Semiconductor is introducing a family of CCRs from 20 mA up to 150 mA in packages as small as a SOD123 up to a D-Pak. All of the packages are thermally robust providing a simple design solution. These devices have a 45 V continuous breakdown voltage with an ESD rating above 8 KV. A typical circuit overhead voltage of 1.8 V. The 20, 25 & 30 mA devices in SOD-123 and SOT-223 are available today.
We will now review some CCR circuits. Circuit A has a single CCR driving multiple strings of LEDs. This circuit requires the LEDs to be matched exactly in forward voltage because they will not share current evenly. The power dissipated in the CCR will be localized in a single package and will require extra thermal design considerations. If one string of LEDs fail the remaining strings will carry the extra current, that could cause them to be damaged. Circuit B has a CCR for each LED string. This circuit does not require the LEDs to be forward voltage matched. The CCR power is dissipated in 3 devices simplifying the design. If one string of LEDs fails it has no impact on the other strings .
To achieve higher currents CCRs can be connected in parallel. This circuit shows 18 LEDS in 3 strings of 6 running off 24 V. To drive this circuit with 50 mA, a 20 mA and a 30 mA CCR are connected in parallel. The CCRs will current share without any problems.
The CCR circuit can be easily dimmed by adding a BJT and providing a PWM (pulse width modulation) signal. The light output will be directly proportional to the PWM signal. The average current is less resulting in the average light output being less. The LEDs are still operating at their optimum current.
A simple dimming circuit can be configured by adding a second BJT to provide an A Stable Multi-vibrator. Switch 1 closed the multi-vibrator runs and the LEDs are on 50%. Switch 2 closes the multi-vibrator stops and the LEDs are on full.
This circuit is connected directly to 110 V AC. There is a simple full wave bridge feeding the CCR and LED light string. The high voltage input is offset by the large voltage drop with having 30 LEDs connected in series. The resistor was included in this circuit to facilitate measuring the current through the LEDS. The resistor could be used to help offset the voltage drop across the CCR if there is not sufficient drop across the LEDs. At 110 V RMS input, TP1 has a peak to peak voltage of 156 V. TP2 shows that the peak voltage across the LEDs and resistor is controlled at 108 V. The current probe will measure the current through the LEDs. The following slide will show scope traces for 110 V RMS input, 100 V RMS input or -10%, and 120 V RMS input or +10%.
At 110 V RMS input, TP1(the yellow trace) has a peak to peak voltage of 156 V. TP2 (blue Trace) shows that the peak voltage across the LEDs and resistor is controlled at 108 V. It also shows that the LEDs are on 52% of the time. The current probe (green trace) measures the current through the LEDs at 25 mA. At 100 V RMS input or -10%, TP1 has a peak to peak voltage of 142 V. TP2 shows that the peak voltage across the LEDs is still controlled at 108 V, the LEDs are on 47% of the time. The current probe continues to measures 25 mA. At 120 V RMS input or +10%, TP1 now has a peak to peak voltage of 170 V. TP2 shows that the voltage across the LEDs is maintained at 108 V. It also shows that the on time is 56%. The current probe again shows 25 mA. A +/- 10% change in RMS voltage input results in an approximate +/- 10% change in light output
In a CCR circuit, the maximum power dissipated depends on the maximum voltage being applied cross it. It is important to select a thermally robust package and ensure the efficient copper on the PCB to dissipate the heat generated. These graphs show that as the ambient temperature increases , the PCB requires a larger copper pad to dissipate the same amount power. From the graphs, we can see the SOT-223 package is thermally efficient package compared to SOT-123 package.
In summary, the LED in the CCR circuit had a consistent brightness over a wide voltage range, both low and high, and they were also protected at high voltages. Therefore, the CCR allows the user to achieve the expected long life of the LED array. Since LED brightness is determined by operating current, optimum intensity will be attained by using a CCR approach to maintain consistent luminosity over the wide variation of battery voltage. SOT−223 package devices improve power dissipation.
Thank you for taking the time to view this presentation on “ Constant Current Regulator for Driving LEDs ” . If you would like to learn more or go on to purchase some of these devices, you may either click on the part list link, or simply call our sales hotline. For more technical information you may either visit the On Semiconductor site, or if you would prefer to speak to someone live, please call our hotline number, or even use our ‘live chat’ online facility. You may visit Element 14 e-community to post your questions.