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[*] [+] [-] [x] [A+] [a-]  
[l] at 3/26/23 7:00am
Understanding the known factors of LEDs to help evaluate LED system lifetime discussed in this white paper from Lumileds. Link here (PDF) One of the strongest propositions of power Light Emitting Diodes (LEDs) is their long lumen maintenance their ability to continue producing light output for many years of use, in contrast to most conventional light sources, which force users to go through repeated and frequent failure-and-replacement cycles. The market perception of an LED’s reliability is reinforced by the widespread practice among lighting manufacturers of offering long warranties on their LED luminaires.

[Category: app notes, app note, LED, led lighting, Lumileds]

[*] [+] [-] [x] [A+] [a-]  
[l] at 3/19/23 11:00am
App note from Richtek on the comparison of current sensing methods using inductors DCR. Link here (PDF) Current sensing plays an important role in DC/DC regulator systems, especially in multi-phase buck converters for CPU VCORE applications. In VCORE applications, the current signals are used to decide the load-line droop, per-phase current balance, current reporting, and over current protection. Moreover, if the control topology is current mode, the current signal will directly affect the system stability. Therefore achieving accurate current signals is very important. Generally, the inductor DC resistance (DCR) current sensing technique is widely used in CPU voltage regulator (VR) applications due to its lossless characteristic. However, the DCR current sensing method needs to parallel an RC network beside the inductor, and is likely to be near noisy nodes like the phase node or other PWM signals. It offers many opportunities to add noise which may decrease the current sensing accuracy. In addition, the offset and bandwidth of the current sensing op amp can also decrease the sensed current signal accuracy or distort the current signal, and generally present a great challenge to acquiring a clean current signal.

[Category: app notes, app note, Current sensing, Richtek]

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[l] at 3/19/23 7:00am
App note from Richtek about thermal resistance calculation using component thermal parameters found on datasheets. Link here (PDF) Thermal issue has been a crucial topic for a long time since high power density and low cost requirements became popular. As a power engineer, the assessment of maximum allowable power dissipation of every component in the system is one of the most important topics when developing a brand new product with good reliability. Generally, each component has a specific thermal characteristics table, which can be found in the datasheet. There are many thermal resistance listed in the table, including θJA, θJB, θJC…etc.

[Category: app notes, app note, Richtek, Thermal resistance]

[*] [+] [-] [x] [A+] [a-]  
[l] at 3/12/23 11:00am
App note from Nexperia on how MOSFETs imperfection can cause imbalance current when paralleled, and how these problems are solved. Link here (PDF) In today’s automotive and power industries, higher power requirements are leading to more designs that require lower RDSon. Sometimes this is not achievable with a single packaged MOSFET and the design will need to make use of two or more devices in parallel. Higher power applications could also require the use of high performance substrates like heavy copper PCB, IMS (Insulated Metal Substrate) or DBC (Direct Bonded Copper) and even bare dies. By paralleling, the total current and thus dissipation is shared between each device. However, this is not as simple as applying Kirchhoff’s current law: MOSFETs are not identical and thus they don’t share equally.

[Category: app notes, app note, MOSFETS, nexperia]

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[l] at 3/12/23 8:07am
App note from Nexperia on an explanation of the derivation of the maximum drain current as a function of pulse duration rating. Link here (PDF) Historically the IDM capability is shown in the limiting values section of the data sheet for tp ≤ 10 µs. ID at DC (continuous) is also shown. IDM is traditionally specified as four times the theoretical value of ID at DC. The IDM rating here is more than four times the ID as the ID specified is limited by the package, rather than the silicon itself. It is difficult for the user to know what the capability would be at other time durations. Some information can be gleaned from the Safe Operating Area (SOA) graph, however it is still hard to assess the actual capability for different time intervals. The aim of this new IDM graph is to provide information regarding the current handling capability of the MOSFET for any time duration in the range provided. It should be noted that only the current carrying capability due to conduction losses is considered. Additional losses incurred due to switching events (linear mode and avalanche) may take the device junction temperature beyond the 175 ˚C limit and cause damage to the device.

[Category: app notes, app note, MOSFET, nexperia]

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[l] at 3/5/23 10:14am
App note from Littlefuse intended to give an overview of the available systems, the strength and weaknesses of each combination, and to help the designer in the selection of the best fuse and holder solution for each application. Link here (PDF) 520 mm fuses continue to be the most widely used components for primary and secondary circuit protection. Although the technology is over 50 years old, the current usage is still estimated to be around 3 billion units per year. These fuses remain popular because: • they are available anywhere in the world • they are both reliable and inexpensive • they offer breaking capacities up to 1500 A Depending on the requirements and expectations of the designer, there are various methods of mounting the 520 mm fuses in the electronic appliance. These range from fuse clips, normally the cheapest option, to comprehensive shock safe fuse holder systems.

[Category: app notes, app note, Fuse, Littlefuse]

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[l] at 2/26/23 10:00am
Sample circuit of high precision programmable current source from Analog Devices. Link here (PDF) Digitally controlled current sources are critical functions in a variety of applications, such as power management, solenoid control, motor control, impedance measurement, sensor excitation, and pulse oximetry. Here we describe three current sources with serial interface digital control using DACs, op amps, and MOSFET transistors. The DACs selected are high resolution (14- or 16-bit), low power CMOS with standard serial interfaces. The two DACs (AD5543 and AD5446) are both compatible with most DSP interface standards and also SPI, QSPI, and MICROWIRE. The external reference voltage input allows many output level variations, up to 10 V. The combination of parts represents industry-leading small PC board area, low cost, and high resolution. The three designs offer low risk solutions and use industry-standard parts.

[Category: app notes, Analog Devices, app note, current source]

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[l] at 2/26/23 6:26am
Low side current monitoring sample circuit from Analog Devices. Link here (PDF) The circuit monitors current in individual channels of −48 V to better than 1% accuracy. The load current passes through a shunt resistor, which is external to the circuit. The shunt resistor value is chosen so that the shunt voltage is approximately 50 mV at maximum load current. The measurement result from the AD7171 is provided as a digital code utilizing a simple 2-wire, SPI-compatible serial interface. The entire circuit operates on a single +3.3 V supply. Optional galvanic isolation is provided by the ADuM5402 quad channel isolator. In addition to isolating the output data, the ADuM5402 digital isolator can also supply isolated +3.3 V for the circuit. The ADuM5402 is not required for normal circuit operation unless galvanic isolation is needed. This combination of parts provides a accurate high voltage negative rail current sense solution with a small component count, low cost, and low power. The accuracy of the measurement is primarily determined by resistor tolerances and the accuracy of the band gap reference, and is typically better than 1%.

[Category: app notes, Analog Devices, app note, Current sense]

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[l] at 2/19/23 10:00am
A good read on this app note from AVX on thermal stresses that leads to device failure on chip capacitors. Link here (PDF) Thermal shock behavior of multilayer ceramic chip capacitors was evaluated for different ceramic dielectrics with varying construction and design considerations, effects of terminations and role of physical defects to decrease the thermal stresses and decrease failure rates. Parameters such as thermal diffusivity including surface heat transfer coefficient, elastic modulus and thickness of chips are used to explain the results. A secondary goal of this evaluation was to identify the significant wave soldering parameters which could be utilized to eliminate the thermal shock failures of these chips.

[Category: app notes, app note, AVX, SMD soldering]

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[l] at 2/19/23 6:24am
App note from ROHM on known dropout voltage values for you to consider in designing with their linear regulator. Link here (PDF) The dropout voltage is the difference between the input and output voltages that is necessary for the stabilizing operation of a linear regulator. When the input voltage approaches the output voltage, stabilizing operation cannot be maintained and the output starts dropping in proportion to the input. The voltage at which this situation starts, i.e., the difference between the input and output voltages that is necessary for the stabilizing operation, is referred to as the dropout voltage.

[Category: app notes, app note, linear regulator, ROHM]

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[l] at 2/5/23 6:00am
App note from Alpha & Omega Semiconductor on added input protection for USB-C against voltage spikes/ringing that can damage the inputs of USB-C power switches. Link here (PDF) USB Type C protection power switches such as the AOZ132xDI and AOZ1398xDI product family (AOZ1327/1376, AOZ13984/13987/13929) are powerful and effective protection ICs, which protect downstream devices from any abnormal power situation such as over/under voltage, over/surge/reverse currents, overpower, and over-temperature conditions, to name a few. However, the type C power switch needs protection when the voltage spike goes over its limit, i.e., Plug/unplug events. It is violent affairs that can interact with board and cable inductances and input capacitances to produce voltages beyond the maximums allowed by the internal control circuit. Another case is the part shutdown at faults with high peak current. In this case, the fast shutdown can make the input cable inductance resonant with input caps, causing the high input ringing voltage. For this case, enough input caps can slow down the ringing frequency and lower the ringing voltage. In both cases, the overvoltages can be controlled or eliminated by using enough input capacitors, proper component placement, and transient voltage suppressors (TVS)

[Category: app notes, alpha and omega semiconductor, app note, USB-C]

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[l] at 1/29/23 10:00am
App note from Holtek on their HT7K1xxx series drive control that replace limit switches but uses speed reduction instead when controlling motor actuation. Link here (PDF) In actuator applications, when a valve or an actuator has reached the end of its stroke, the motor input power will be switched off using a limit switch. This is called mechanism control. If the motor runs at full speed from start to stop during the whole stroke, this may cause the motor to hit the end of its stroke without reducing speed when the limit switch is triggered. There are two main problems here in using mechanism control. One is aging of the limit switch and the other is that a collision will occur when the valve or the actuator reaches the end of stroke without speed reduction, which could cause damage to the gear mechanism.

[Category: app notes, app note, Holtek, motor control]

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[l] at 1/29/23 6:28am
App note from Holtek on their HT45F4050 device which discuss its hardware and software application. Link here (PDF) NFC, which is an acronym for Near Field Communication, is a technology allowing wireless connection between devices using a simple touch. NFC technology operates at a frequency of 13.56MHz with an operating distance within 10cm. It has three data rates of 106Kbit/s, 212Kbit/s and 424Kbit/s, and supports three operating modes. These are card emulation, card read/write and P2P. Its operating standard is compatible with Sony’s FeliCa standard (Type F) and Philips’ MIFARE standards (ISO 14443A – Type A; ISO 14443B – Type B). The HT45F4050 supports a data rate of 106Kbit/s and is mainly used for card emulation. It follows the ISO14443A Type A standard.

[Category: app notes, app note, Holtek, NFC]

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[l] at 1/22/23 6:00am
App note from International Rectifier on various solid state relay circuits. Link here (PDF) Manufacturers of satellites, satellite launch vehicles, and tactical weapon systems face many challenges when designing electro-mechanical relays (EMR) into their systems. Some method of cushioning must be employed in order to prevent false relay operation when encountering shock and vibration. In addition, hash filters are sometimes necessary to debounce the contacts, thus adding space and weight. However, Solid State Relays (SSR) are immune to the shock and vibration levels normally encountered, and do not need contact filters. Hence, the use of Solid State Relays in place of the mechanical type leads to a more reliable end product.

[Category: app notes, app note, International Rectifier, solid state relay]

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[l] at 1/22/23 6:00am
App note from Holtek on their dedicated IR remote IC. Link here (PDF) The HT62104 is a high performance infrared remote encoder capable of encoding a signal with a 3-bit start code, 2-bit custom code and 7-bit data code. The HT62104 device has 8 key inputs. When one of the keys is triggered, the programmed code is generated and transmitted via an IR (38kHz carrier) transmission medium.

[Category: app notes, app note, Holtek, IR remote]

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[l] at 1/15/23 10:00am
Article from Texas Instruments on various common misconceptions about Hall-effect sensors as well as real-world applications. Link here (PDF) Hall-effect sensors are commonly used in automotive and industrial systems for applications including proximity detection, linear displacement measurement and rotary encoding. Currently, the high system performance requirements of modern applications have led to IC manufacturers increasing sensitivity accuracy, integrating more functionality, expanding available sensing directionalities and lowering power consumption in their devices helping extend the use of Hall-effect sensors for decades to come.

[Category: app notes, app note, hall-effect, Texas Instruments]

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[l] at 1/15/23 6:57am
Technical note from Texas Instruments on their high power density eFuse used in hot swappable servers. Link here (PDF) As demand for data increases, so does demand for servers and data centers, and thus higher demand for power. Industry trends suggest that power per rack, which was 4 kW in 2020, will be as high as 20 kW in 2025.Given limited physical real estate available for data centers and servers, the delivery of more power in less area is known as a high power density requirement in server power architectures. Increasing the efficiency of server power supplies can also keep cooling costs down. Servers are usually scalable and are hot-swappable in order to meet different processing requirements and maintain high system availability. To achieve seamless hot-swap functionality, server motherboards and power distribution boards employ hot-swap controllers or eFuses. Components such as eFuses in server power supplies need to provide higher current to meet increased server power requirements. Protection devices such as hot swaps and eFuses also need to handle high peak current to match the higher peak-processing capabilities of modern microprocessors in servers.

[Category: app notes, app note, eFuses, Texas Instruments]

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[l] at 1/8/23 10:00am
App note from Analog Devices about a low power overcurrent indicator circuit using their micropower comparator LT6703. Link here This circuit design is to monitor the average current in an AC line-connected load and to illuminate an LED if it exceeds a specified level.

[Category: app notes, Analog Devices, app note, current measurement]

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[l] at 1/5/23 7:21am
Mare shared a step by step guide to setting up the multiband WEB SDR with remote receivers: I recently built homelab server based on “proper” server infrastructure with plenty of RAM and lots of processing cores. I decided to setup OpenWebRx in one linux virtual machine with raspberry pi only as remote receivers serving single user (server itself). See the full post on Mare & Gal Electronics blog.

[Category: R-Pi, SDR, openwebrx]

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[l] at 1/1/23 1:59am
Happy New Year! Thank you for reading the blog and being part of our community in 2022! We’re looking forward to more open hardware projects, more how-tos, more videos, more free PCBs, and more hacking in 2023.

[Category: Holiday, holiday, New Year]

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[l] at 12/25/22 6:58am
Alpha & Omega Semiconductors app note about MOSFETs used in battery protection circuits. Link here (PDF) Power MOSFETs are required to be connected in series between the lithium-ion battery pack and the output load. At the same time, a dedicated IC is used to control the on and off of the MOSFET for managing the charge and discharge of the battery. In consumer electronic systems such as cell phones, laptops, etc., the complete circuit system with control IC, power MOSFET, and other electronic components is called the Protection Circuit Module (PCM). The PCM requires a low on-resistance MOSFET, so N-channel power MOSFETs are usually used. Some applications use P-channel MOSFETs on the positive end due to simple and flexible driving. However, P-channel MOSFETs on-resistance is relatively higher than N-channel MOSFETs and the selection is also limited.

[Category: app notes, alpha and omega semiconductor, app note, battery protection, MOSFETS]

As of 3/31/23 7:44pm. Last new 3/26/23 7:31am.

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