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Finally took the plunge and started to solder NOT, AND, and OR gates onto perfboard. Breadboarded an XOR this evening which I got working without frying anything too! Used 2N7000s for all of these (please don’t attack me for forgetting gate resistors). I’m super excited to start expanding into more complex projects soon!.. submitted by /u/Diligent_Ad282 [link] [comments]

Introduction

Among all power factor correction (PFC) topologies, totem-pole bridgeless PFC provides the best efficiency; therefore, it is widely used in servers and data centers. However, closing the current control loop of a continuous conduction mode (CCM) totem-pole bridgeless PFC is not as straightforward as it is for a traditional PFC. A traditional PFC operating in CCM employs an average current-mode controller [1], as shown in Figure 1, where VREF is the voltage-loop reference, VOUT is the sensed PFC output voltage, Gv is the voltage loop, VIN is the sensed PFC input voltage, IREF is the current-loop reference, IIN is the sensed PFC inductor current, GI is current loop, and d is the duty ratio of pulse-width modulation (PWM). Since the bridge rectifier is used in a traditional PFC, all these values are positive, and current feedback signal IIN is the rectified input current signal.

Figure 1 Average current-mode controller for PFC where all the parameters listed have positive values and IIN is the rectified input current signal. Source: Texas Instruments

New feedback signal

Since the inductor current in the totem-pole bridgeless PFC is bidirectional, the current-sense method used in traditional PFC will not work. Instead, you will need a bidirectional current sensor such as Hall-effect sensor to sense the bidirectional inductor current and provide a feedback signal to the control loop.

The output of the Hall-effect sensor will not 100% match the sensed current, though. For example, if the sensed current is a sine wave, then the output of the Hall-effect sensor is a sine wave with a DC offset, as shown in Figure 2. Thus, you can’t use it as the feedback signal in the current-mode controller shown in Figure 1, and you will have to modify the controller to accommodate this new feedback signal. In this power tip, I’ll describe three ways to close the current control loop with this new feedback signal.

Figure 2 Totem-pole bridgeless PFC and its current-sense signal showing that the Hall-effect sensor output will not 100% match the sensed current. Source: Texas Instruments

Method 1: Controllers without a negative loop reference

Some digital controllers, such as the UCD3138 from Texas Instruments (TI), use a hardware state machine to implement the control loop; therefore, all of the input signals to the state machine must be greater or equal to zero. In such cases, follow these steps to close the current control loop:

1. Sense the AC line and AC neutral voltage through two analog-to-digital-converters (ADCs) separately.
2. Use firmware to rectify the sensed VAC signal, as shown in Equation 1 and Figure 3.

Figure 3 Using the firmware shown in Equation 1 to rectify the sensed input voltage VAC. Source: Texas Instruments

3. Calculate the sinusoidal reference, VSINE, using the same method as when calculating IREF in traditional PFC, as shown in Equation 2 and Figure 4.

Figure 4 Calculating a sinusoidal reference (VSINE) using the same method as when calculating IREF in traditional PFC. Source: Texas Instruments

4. Use a Hall-effect sensor output as the current feedback signal IIN directly (Equation 3).

5. During the positive AC cycle, if you compare the shape of VSINE and the Hall-effect sensor output, they have the same shape. The only difference is the DC offset. Use Equation 4 to calculate the current-loop reference, IREF.

6. The control loop has standard negative feedback control. Use Equation 5 to calculate the error that goes to the control loop:

7. During the negative AC cycle, if you compare the shape of VSINE and the Hall-effect sensor output, the difference is not only the DC offset; their shapes are opposite as well. Use Equation 6 to calculate the current-loop reference, IREF.

8. During the negative AC cycle, the higher the inductor current, the lower the value of the Hall-effect sensor output. The control loop needs to change from negative feedback to positive feedback. Use Equation 7 to calculate the error going to the control loop.

Method 2: A pure firmware-based controller

For a pure firmware-based digital controller such as the TI C2000 microcontroller, the control loop is implemented with firmware, which means that the internal calculation parameters can be positive or negative. In such cases, follow these steps to close the current control loop:

1. Sense the AC line and AC neutral voltage through two ADCs. Then use the line voltage to subtract the neutral voltage to obtain VIN, as shown in Equation 8 and Figure 5.

Figure 5 Calculating VIN after using the line voltage to subtract the neutral voltage. Source: Texas Instruments

2. Calculate the sinusoidal current-loop reference, IREF, using the same method as in traditional PFC, as shown in Equation 9 and Figure 6.

Figure 6 Calculating IREF using the same method as the traditional PFC. Source: Texas Instruments

3. If you compare the shape of IREF and the Hall-effect sensor output, they have the same shape; the only difference is the DC offset. Use Equation 10 to calculate the input current feedback signal, IIN. Figure 7 shows the waveform.

Figure 7 The waveform of the Hall sensor output and DC offset to calculate IIN. Source: Texas Instruments

4. During the positive AC cycle, the control loop has standard negative feedback control. Use Equation 11 to calculate the error going to the control loop:

5. During the negative AC cycle, the higher the inductor current, the lower the value of the Hall-effect sensor output; thus, the control loop needs to change from negative feedback to positive feedback. Use Equation 12 to calculate the error going to the control loop.

Method 3: Duty-ratio feedforward control

Total harmonic distortion (THD) requirements are becoming stricter, especially in server and data-center applications. Reducing THD necessitates pushing the control-loop bandwidth higher and higher. High bandwidths reduce phase margins, resulting in loop instability. The limited PFC switching frequency also prevents bandwidths from going very high. To solve this problem, you can add a precalculated duty cycle to the control loop to generate PWM; this is called duty-ratio feedforward control (dFF) [2], [3].

For a boost topology operating in CCM mode, Equation 13 calculates dFF as:

This duty-ratio pattern effectively produces a voltage across the switch whose average over a switching cycle is equal to the rectified input voltage. A regular current-loop compensator changes the duty ratio around this calculated duty-ratio pattern. Since the impedance of the boost inductor at the line frequency is very low, a small variation in the duty ratio produces enough voltage across the inductor to generate the required sinusoidal current waveform so that the current-loop compensator does not need to have a high bandwidth.

Figure 8 depicts the resulting control scheme. Adding the calculated dFF to the traditional average current-mode control output, dI, results in the final duty ratio, d, used to generate the PWM waveform to control PFC.

Figure 8 Duty-ratio feedforward control for PFC where adding the calculated dFF to the traditional average current-mode control output, dI, results in the final duty ratio, d, used to generate the PWM waveform to control PFC. Source: Texas Instruments

To leverage the advantages of dFF in a totem-pole bridgeless PFC, follow these steps to close the current loop:

1. Follow steps 1, 2, 3, 4 and 5 from Method 2.
2. Calculate dFF, as shown in Equation 14. Since VIN is a sine wave and its value is negative in a negative AC cycle, use its absolute value for the calculation.

3. Use Equation 15 to add dFF to the GI output, dI, and obtain the final d.

You can also use dFF control for a hardware state machine-based controller; for details, see reference [2].

Closing the current loop

Closing the current loop of a totem-pole bridgeless PFC is not as straightforward as in a traditional PFC; it may also vary from controller to controller. This power tip can help you eliminate the confusion around control-loop implementations in a totem-pole bridgeless PFC, and choose the appropriate method for your design.

Bosheng Sun is a systems engineer in Texas Instruments, focusing on developing digital controlled high-performance AC/DC solutions for server and industry applications. Bosheng received an M.S. degree from Cleveland State University in 2003, and a B.S degree from Tsinghua University in Beijing in 1995, both in Electrical Engineering. He holds 5 US patents.

Related Content

• Power Tips #108: Current sensing considerations in a bridgeless totem pole PFC
• A comparison of interleaved boost and totem-pole PFC topologies
• Power Tips #116: How to reduce THD of a PFC
• Power Tips #132: A low-cost and high-accuracy e-meter solution

References

1. Dixon, Lloyd. “High Power Factor Preregulator for Off-Line Power Supplies.” Texas Instruments Power Supply Design Seminar SEM600, literature No. SLUP087, 1988.
2. Sun, Bosheng. “Duty Ratio Feedforward Control of Digitally Controlled PFC.” Power Systems Design, Dec. 3, 2014.
3. Van de Sype, David M., Koen De Gussemé, Alex P.M. Van den Bossche, and Jan A. Melkebeek. “Duty-Ratio Feedforward for Digitally Controlled Boost PFC Converters.” Published in IEEE Transactions on Industrial Electronics 52, no. 1 (February 2005): pp. 108-115.

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For fiscal first-quarter 2025 (ended 27 December 2024), Skyworks Solutions Inc of Irvine, CA, USA (which manufactures analog and mixed-signal semiconductors) has reported revenue of $1068m, down 11% on $1201.5m a year ago but up 4% on $1025m last quarter and slightly above the midpoint of the $1050–1080m guidance range. This was despite a muted demand environment and ongoing inventory digestion across selective end markets...

India’s healthcare landscape is rapidly evolving with the integration of advanced robotics into medical procedures. Although still in its nascent stage compared to global markets, the country is witnessing a surge of innovation driven by both established technology conglomerates and agile startups. These companies are developing a range of medical robots—from surgical assistants and rehabilitation devices to automated hospital systems—designed to enhance precision, improve patient outcomes, and reduce overall procedural risks.

Below are the top 10 medical robot manufacturers in India that are paving the way for a smarter, more efficient healthcare ecosystem:

1. Robosoft Systems
   Based in Bangalore, Robosoft Systems has emerged as a leader in the robotics domain with diversified applications in healthcare. Their portfolio includes robotic platforms for surgical assistance and post-operative rehabilitation. Utilizing advanced sensor integration, precision actuation, and real-time feedback loops, their systems assist surgeons in executing minimally invasive procedures, thereby reducing recovery times and minimizing patient trauma.
2. Tata Elxsi
   A stalwart in design and technology innovation, Tata Elxsi has leveraged its expertise in embedded systems and AI to develop cutting-edge robotics solutions for the medical field. Their research and development initiatives focus on medical imaging and robotic control systems, enabling enhanced precision in surgical procedures. The company’s solutions incorporate robust safety protocols and user-friendly interfaces, making them ideal for integration in modern operating theaters.
3. SurgiBotix Innovations
   SurgiBotix Innovations is a dynamic startup committed to the development of robotic systems for minimally invasive surgeries. Their surgical robots are designed with teleoperation and semi-autonomous functionalities, allowing for remote surgical assistance and precise manipulation of instruments. By incorporating machine learning algorithms, these robots can adapt to complex surgical environments, ensuring high accuracy and reducing the incidence of human error.
4. MedTech Robotics Pvt Ltd
   Focusing on the intersection of robotics and surgical technology, MedTech Robotics Pvt Ltd designs robotic arms specifically for delicate surgical procedures. Their systems prioritize precision and stability, which are crucial in procedures that demand high accuracy, such as neurosurgery and microsurgery. Continuous improvements in real-time motion control and force feedback mechanisms are at the core of their design philosophy.
5. Skanray Technologies
   Traditionally recognized as a reliable medical device manufacturer, Skanray Technologies is expanding its horizon by venturing into the realm of medical robotics. Their new initiatives target the development of robotic platforms that assist surgeons during complex operations, integrating diagnostic imaging with robotic precision. This fusion of technologies is expected to enhance intraoperative decision-making and lead to better clinical outcomes.
6. IntelliMed Robotics
   IntelliMed Robotics is dedicated to developing robotic solutions that focus on patient rehabilitation and monitoring. Their innovative systems incorporate AI-driven analytics and sensor networks to track patient progress in real-time. These systems are particularly effective in rehabilitation centers, where robotic-assisted physiotherapy can be customized to meet individual patient needs, accelerating recovery while ensuring patient safety.
7. BioMech Robotics
   Specializing in exoskeletons and assistive devices, BioMech Robotics addresses the challenges of patient mobility and long-term care. Their products, which include robotic exoskeletons and wearable assistive devices, are designed to help patients with mobility impairments regain independence. By integrating ergonomic design with advanced control systems, BioMech’s solutions support both rehabilitation and eldercare, providing a significant boost to quality of life.
8. InnoMed Automation
   InnoMed Automation is making strides in automating routine hospital operations. Their robotic systems are implemented in various settings—from automated pharmacy dispensaries to laboratory sample handling units. These systems are engineered to reduce human error, streamline processes, and free up medical professionals to focus on patient-centric tasks. The adoption of InnoMed’s solutions is poised to transform operational efficiency in hospitals and diagnostic centers.
9. NextGen Surgical Robotics
   NextGen Surgical Robotics is at the forefront of integrating artificial intelligence with surgical robotics. Their innovative approach employs machine learning to enhance the adaptability and responsiveness of robotic systems during surgery. By continuously learning from surgical data, these robots refine their operational accuracy, ensuring that they are well-equipped to handle the dynamic challenges of complex procedures.
10. Artemis Medical Robotics
    Artemis Medical Robotics combines advanced imaging technologies with robotic precision to develop comprehensive systems for both diagnostic and surgical applications. Their platforms enable real-time imaging integration, providing surgeons with enhanced visualization during operations. This seamless integration of diagnostics and robotics not only improves surgical outcomes but also reduces the duration and invasiveness of procedures.

In conclusion, the landscape of medical robotics in India is rapidly evolving, driven by a convergence of advanced technology, innovative startups, and established industry players. These top 10 manufacturers are at the vanguard of this transformation, leveraging state-of-the-art engineering, AI, and real-time control systems to deliver solutions that are set to redefine patient care and surgical precision in the country. As these technologies mature, we can expect further enhancements in clinical outcomes, operational efficiency, and the overall quality of healthcare delivery in India.

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Silicon carbide wafer manufacturing technology firm TekSiC AB of Linköping, Sweden has added to its Xforge platform with the Xforge PVT, a compact high-temperature induction heating furnace for crystal growth using physical vapor transport in the semiconductor industry and research institutes. With its design, the Xforge PVT offers versatile configurations, ensuring what is claimed to be peak performance across diverse specialized applications...

India’s drone industry is soaring to new heights, fueled by rapid technological advancements and a strong push for indigenous manufacturing. With applications spanning defense, agriculture, logistics, and infrastructure, drones have become a crucial part of India’s modernization efforts. A growing ecosystem of manufacturers is driving innovation, producing high-quality drone components that cater to both domestic and global markets. From flight controllers and propulsion systems to AI-powered navigation and surveillance solutions, these companies are shaping the future of unmanned aerial systems. Here’s a look at the top 10 drone parts manufacturers in India and their impact on this evolving sector.

1. ideaForge Technology Pvt. Ltd.

Established as a pioneer in the Indian drone sector, ideaForge specializes in developing unmanned aerial systems (UAS) tailored for defense, surveillance, and industrial applications. Their drones are renowned for robustness and high performance, capable of operating in challenging environments to provide real-time situational awareness. Key features include extended endurance, substantial payload capacity, and stable flight performance. These attributes have made ideaForge a preferred choice for defense and security agencies engaged in border surveillance, reconnaissance, and intelligence operations.

2. Asteria Aerospace

Asteria Aerospace offers comprehensive drone-based solutions for both government and enterprise sectors. With in-house capabilities spanning hardware design, software development, and manufacturing, Asteria delivers end-to-end services. Their product lineup includes drones like the A200, A200-XT, A410-XT, and AT-15, alongside the SkyDeck cloud platform for drone operations analysis. These solutions cater to industries such as defense, homeland security, oil and gas, mining, and agriculture, providing critical services like infrastructure inspection and aerial surveillance.

3. Garuda Aerospace

Positioned as a Drone-as-a-Service (DaaS) provider, Garuda Aerospace delivers innovative drone solutions across sectors including agriculture, surveillance, and industrial applications. Their drones are designed for tasks such as pesticide spraying, crop monitoring, and infrastructure inspection. Garuda Aerospace emphasizes indigenous manufacturing, aligning with the “Make in India” initiative to reduce reliance on imported components and promote self-sufficiency in drone technology.

4. Paras Defence and Space Technologies

Paras Defence and Space Technologies is a prominent player in the defense and space sectors, extending its expertise to drone technology. The company focuses on developing and manufacturing drone components and subsystems, including electro-optic systems, stabilizers, and gimbals. Their contributions are integral to enhancing the capabilities of various drone platforms used in defense and industrial applications.

5. Zen Technologies

Specializing in defense training solutions, Zen Technologies has diversified into the drone industry by offering unmanned systems and associated components. Their product range includes target drones and surveillance UAVs designed to meet the rigorous standards of defense applications. Zen Technologies’ focus on research and development ensures the integration of advanced features and compliance with military specifications.

6. Dhaksha Unmanned Systems

Dhaksha Unmanned Systems is dedicated to providing unmanned aerial solutions for homeland security and commercial markets. Their expertise lies in developing UAS technology that addresses real-time demands, offering products suitable for surveillance, reconnaissance, and industrial applications. The company’s focus on innovation and adaptability makes it a significant contributor to India’s drone ecosystem.

7. TechEagle

TechEagle is a leading innovator in on-demand drone delivery solutions, designing drones optimized for sectors such as maritime, defense, e-commerce, and healthcare. Their drones are engineered to perform in diverse environments, facilitating tasks like parcel delivery, medical supply transport, and surveillance operations. TechEagle’s commitment to advancing drone technology contributes to the efficiency and reach of logistics and delivery services in India.

8. Marut Drones

Focusing on agricultural applications, Marut Drones develops drones equipped for tasks such as pesticide spraying, crop health monitoring, and afforestation efforts. Their solutions aim to enhance agricultural productivity and sustainability by providing precise and efficient tools for farmers. Marut Drones’ technology supports large-scale farming operations and environmental conservation projects.

9. Skylark Drones

Skylark Drones offers drone-based solutions across various industries, including solar energy, infrastructure, and agriculture. Their services encompass aerial surveys, mapping, and inspection, providing clients with accurate data and insights for informed decision-making. Skylark’s technology aids in optimizing operations, reducing costs, and improving safety standards across sectors.

10. Karkhana.io

Karkhana.io is a B2B on-demand manufacturing platform with capabilities to produce custom drone parts and components. Utilizing materials such as carbon fiber, polymers, and metals, Karkhana.io supports startups, SMEs, and large enterprises from prototyping to production stages. Their services ensure that drone manufacturers have access to high-quality, tailor-made components essential for building advanced UAVs.

These companies exemplify the dynamic and rapidly evolving landscape of drone technology in India. Their contributions span from complete drone systems to specialized components, collectively bolstering the country’s capabilities in various sectors such as defense, agriculture, surveillance, and logistics. As the industry continues to grow, these manufacturers are poised to play pivotal roles in shaping the future of unmanned aerial technology in India.

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Teledyne e2v, a Teledyne Technologies company and global innovator of imaging solutions, introduces Lince5M NIR, a state-of-the-art high–speed CMOS image sensor. Leveraging Teledyne e2v’s advanced imaging technologies, this new sensor delivers enhanced performance in both visible and near-infrared (NIR) wavelengths, making it ideal for a wide range of commercial, industrial, and medical applications.

The Lince5M NIR is a monochrome image sensor with a resolution of 5.2 megapixels (2,560 x 2,048). Building on the established Lince5M, this new sensor combines high–speed capabilities and high Quantum Efficiency (35% at 850 nm) in both visible and near-infrared wavelengths. It achieves a high frame rate of 250 fps (full resolution, 12-bit ADC), using the 24 LVDS output channels. Lince5M NIR delivers superior performance for demanding applications that require sharp images at very high-speeds and in low-light conditions, such as motion capture, sport analytics, industrial metrology, retinal imaging, and intelligent traffic monitoring. Designed around Teledyne e2v’s 5 µm global shutter pixel, this image sensor offers a dynamic range of 55 dB in standard mode and over 100 dB in High Dynamic Range mode, making it perfect for observing high-contrast scenes.

Lince5M NIR is housed in a robust 28 x 28 mm 181 PGA (Pin-Grid Array) ceramic package and features a 1-inch optical format compatible with a broad range of C-mount lenses, for cost-effective camera integration. With an operating temperature range from -40°C up to 125°C, the Lince5M NIR is suitable for both indoor and outdoor applications.

François Trolez, Marketing Manager at Teledyne e2v, said, “We are very pleased to release Lince5M NIR, specifically designed to offer unique features for high–speed imaging beyond the visible spectrum, with high performance in the near-infrared region. With its robust design, Lince5M NIR meets the demands of both industrial and commercial applications. Camera manufacturers currently using our Lince5M will find it easy to switch to Lince5M NIR, as both products share the same mechanical and electrical interfaces. This new product will enhance our ability to address new markets and applications.”

Lince5M NIR will be showcased during Vision China, Shanghai, China from 26-28 March 2025. Visit us on Teledyne stand 5413 in Hall W5 or contact us online for more information.

Documentation, samples, and kits for evaluation or development are available upon request.

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