The Kynix Blog

A simple and efficient PWM lamp dimmer using timer IC NE555 is discussed in this article. Yesterdays linear regulator based dimmers can only attain a maximum efficiency  of 50% and are far inferior when compared to the PWM based dimmers which can hit well over 90% efficiency. Since less amount of power is wasted as heat, the switching elements of PWM dimmers require a smaller heat sink and this saves a lot of size and weight. In simple words, the most outstanding features of the PWM based lamp dimmers are high efficiency and low physical size. The circuit diagram of a 12V PWM lamp dimmer is shown below. As you can see, NE555 timer IC which is wired as an astable multivibrator operating at 2.8KHz forms the heart of this circuit. Resistors R1,R2, POT R3 and capacitor C1 are the timing components. Duty cycle of the IC’s output can be adjusted using the POT R3. higher the duty cycle means higher the lamp brightness and lower the duty cycle means lower the lamp brightness. Diode D1 by-passes the lower half of the POT R3 during the charging cycle of the astable multivibrator. This is done in order to keep the output frequency constant irrespective of the duty cycle. Transistors Q1 and Q2 forms a darlington driver stage for the 12V lamp. Resistor R4 limits the base current of transistor Q1.Understanding the variable duty cycle astable multivibrator.As I have said earlier, the variable duty cycle astable multi vibrator based on NE555 forms the foundation of this circuit and a good knowledge on it is essential for designing projects like this. For the ease of explanation the timing side of the astable multivibrator is redrawn in the figure below.Upper and lower halves of the POT R3 are denoted as Rx and Ry respectively. Consider the output of the astable multivibrator to be high at the starting instant. Now the capacitor C1 charges through the path R1, Rx, and R2. The lower half of POT R3 ie; Ry is out of the scene because the diode D1 by-passes it. When the voltage across the capacitor reaches 2/3 Vcc, the internal upper comparator flips its output which makes the internal flip flop to toggle its output. As a result the output of the astable multivibrator goes low. In simple words, the output of the astable multivibrator remains high until the charge across C1 becomes equal to 2/3 Vcc and here it is according to the equation Ton =0.67(R1+Rx+R2)C1.Since the internal flip flop is set now, the capacitor starts discharging through the path R2,Ry into the discharge pin. When the voltage across the capacitor C1 becomes 1/3 Vcc, the lower comparator flips its output and this in turn makes the internal flip flop to toggle its output again. This makes the output of the astable multivibrator high. To be simple, the output of the astable multivibrator remains low until the voltage across the capacitor C1 becomes 1/3 Vcc and it is according to the equation Toff = 0.67(R2+Ry)C1. Have a look at the internal block diagram of NE555 timer shown below for better understanding.How does the frequency remain constant irrespective of the position of POT3 knob?.What ever may be the position of  POT3 knob, the total resistance across it remains the same (50K here). If anything decreases in the upper side (Rx) the same amount will be increased in the lower (Ry) and the same thing gets applied to the higher(Ton) and lower(Toff) time periods. The derivation shown below will help you to grasp the matter easily.With reference to Fig 2, we have:Ton = 0.67(R1+Rx+R2)C1Toff= 0.67(R2+Ry)C1Total time period of the output waveform “T” is according to the equation :T = Ton + ToffThere fore, T = 0.67(R1+Rx+R2+R2+Ry)C1                        T= 0.67(R1+2R2+Rx+Ry)C1We know that Rx+Ry = R3There fore T = 0.67(R1+2R2+R3)C1Therefore frequency F = 1/(0.67(R1+2R2+R3)C1) From the above equation its is clear that the frequency depends only on the value of the components C1, R1, R2  and the over all value of R3 and it has nothing to do with the position of R3 knob.  Ref:KY32-NE555KY32-NE555.NE555DR.NE555P 

The introduction of the LDD-ES8, a customisable gigabit Ethernet switch module for industrial, commercial and building automation data services, has been announced by LDD Technology. The standard LDD-ES8 module is an 8 port unmanaged Ethernet Switch on a PC/104-Plus form factor intended for use in embedded applications. It features a high performance, low latency, switch able to handle full-rate gigabit packets on all ports simultaneously.Auto-negotiation allows each port to operate at 10/100/1000 Mbits with dual LEDs per port to indicate negotiated speed and link activity. Power is provided from the PC/104 stack or through a Molex Microclasp connector. The LDD-ES8 module is designed for fully independent operation but a USB port is provided to allow monitoring of port performance if required. Power consumption is typically 5W with all ports operating at 1 Gbit/sec.The LDD-ES8 Gigabit Ethernet switch was developed in response to a number of enquiries for custom designed products from customers who had been unable to find suitable off-the-shelf products which met their performance, footprint and end product life requirements.LDD Technology is able to offer an efficient and cost-effective customisation service in the event that customers require a design with a different number of ports or in a different form factor. The module has been designed using programmable FPGA technology which offers end users a further range of customisation options not normally found on competitive products based on dedicated devices with limited programmability.This allows customers the option of including the functionality of the standard Ethernet Switch into other designs which may require Ethernet switching as part of a more complex system with additional interfaces or processing being included in the FPGA as required.“Our LDD-ES8 Gigabit Ethernet Switch is an excellent example of how our extensive custom design experience for many different clients can be used to create a flexible standard solution for many applications” commented Malcolm Locke, Managing Director of LDD Technology. Ref:KY32-EP1S60B956C6KY32-XC7K325T-2FFG900CKY32-EPF8636ALC84-3

The CC2640R2F SimpleLink ultra-low-power wireless microcontroller from Texas Instruments (TI) is in stock at Mouser Electronics. Part of TI’s CC26xx SimpleLink family of 2.4GHz devices, the CC2640R2F microcontroller features a small, single-chip system that integrates a flash-based microcontroller and Bluetooth Smart radio to target Bluetooth 4.2 and Bluetooth 5 low-energy applications. The microcontroller combines a 61μA/MHz ARM Cortex-M3 microcontroller and a rich peripheral set that includes an 8.2μA/MHz sensor controller. The 48MHz ARM microcontroller offers 128 kBytes of flash and 28 kBytes of SRAM and supports over-the-air (OTA) updates. The sensor controller is ideal for interfacing external sensors and for collecting analog and digital data autonomously while the rest of the system is in sleep mode. The device includes a 12-bit analogue-to-digital converter, up to 31 general-purpose inputs and outputs (GPIOs), and built-in robust security on chip with one of the simplest radio frequency (RF) and antenna designs available. Minimal RF expertise is required to implement the device, which helps make development and layout extremely easy. The wireless microcontroller is available in 2.7×2.7 mm WCSP and 4×4, 5×5 and 7×7 mm QFN packages, and is designed for a board array of wireless Internet of Things (IoT) applications, including health and fitness, industrial, and home and building automation. With ready-to-use protocol stacks (including the SIMPLELINK-CC2640R2-SDK software development kit for Bluetooth 5), the SimpleLink portfolio of wireless connectivity solutions not only offers designers maximum flexibility and support but also delivers multi-standard capabilities with code- and pin-compatibility across Bluetooth Smart, 6LoWPAN, ZigBee and ZigBee RF4CE.   Ref: KY32-MB91F376GPMCR-GS KY32-MB90F548GSPFV-G KY32-HD6417604SVF20

UK power firm Amantys Power Electronics has developed its next generation IGBT gate drive technology which is being demonstrated this week at the PCIM exhibition in Nuremberg. Called NG Gate Drive, it has been designed to be compatible with IGBT modules known as LinPak, XHP, nHPD2 and SemiTrans20 that are available from several power semiconductor manufacturers.This is achieved because IGBT module variation, such as the position of gate drive connections, is accommodated through use of a module interface card which means the NG Gate Drive can target modules from 1700V to 3300V, and up to 6500V in the future.It will drive up to six IGBT modules in parallel.The company has incorporated its own two-way communication protocol between the gate drive and a central controller, allowing configuration of the gate drive in the target power stack.Configurable parameters, include the gate resistors (Rgon, Rgoff and Rgsoftoff), gate-emitter capacitor (Cge), operating mode (two level or three level) and timeouts such as the fault lock out time and dead time.Module also features multi-level desaturation detection for improved protection of the IGBT module. It records faults that the gate drive has seen during operation.Potential applications could include traction, wind energy and medium voltage motor drives. Ref:KY32-STK672-540KY32-BA5834FM-E2KY32-BD7957FS

Imec, the world-leading research and innovation hub in nanoelectronics and digital technology, announced today at the 2017 Symposia on VLSI Technology and Circuits the world's first demonstration of a vertically stacked ferroelectric Al doped HfO2 device for NAND applications. Using a new material and a novel architecture, imec has created a non-volatile memory concept with attractive characteristics for power consumption, switching speed, scalability and retention. The achievement shows that ferro-electric memory is a highly promising technology at various points in the memory hierarchy, and as a new technology for storage class memory. Imec will further develop the concept in collaboration with the world's leading producers of memory ICs.  Ferro-electric materials consist of crystals that exhibit spontaneous polarization; they can be in one of two states, which can be reversed with a suitable electric field. This non-volatile characteristic resembles ferromagnetism, after which they have been named. Discovered more than five decades ago, ferro-electric memory has always been considered ideal, due to its very low power needs, non-volatile character and high switching speed. However, issues with the complex materials, the breakdown of the interfacial layer and bad retention characteristics have presented significant challenges. The recent discovery of a ferro-electric phase in HfO2, a well-known and less complex material, has triggered a renewed interest in this memory concept."With HfO2, there is now a material with which we can process ferro-electric memories that are fully CMOS compatible. This allows us to make a ferro-electric FET (FeFET) in both planar and vertical varieties," noted Jan Van Houdt, imec's chief scientist for memory technology. "We are working to overcome some of the remaining issues, such as retention, precise doping techniques and interface properties, in order to stabilize the ferro-electric phase. We are now confident that our FeFET concept has all the required characteristics. It is, in fact, suitable for both stand-alone and embedded memories at various points in the memory hierarchy, going all the way from non-volatile DRAM to Flash-like memories. It has particularly interesting characteristics for future storage-class memory, which will help overcome the current bottleneck caused by the differences in speed between fast processors and slower mass memory."Imec recently presented the first, extremely positive results to its partners. The research center is now offering further development and industrialization of the vertical FeFET as a program to all its memory partners, which include the world's major companies producing memory ICs."FeFETs can be used as a technology to build memory very similar to Flash-memory, but with additional advantages for further scaling, simplified processing, and power consumption," added Van Houdt. "With our longstanding R&D and processing experience on advanced Flash, we are uniquely positioned to offer our partners a head start in this exciting opportunity. They can then decide how best to fit ferro-electric memories in their products and chips." Ref:KY32-K9T1G08U0M-YIBOKY32-CY7C1357S-100AXCKY32-AT49BV162AT(T)  

Allegro MicroSystems, LLC announces the release of a new micropower LED driver IC that features an integrated Hall-effect switch. The APS13568 enables compact, elegant, reliable, and fault-tolerant LEDlighting with minimal electrical engineering and low component-count and cost. A single silicon chip integrates: a micropower regulator, a Hall plate, a small-signal amplifier, chopper stabilization, a Schmitt trigger, open drain Hall-Effect switch output, output polarity selection, and an LED driver with soft on/off and short circuit and thermal protection with automatic recovery. The integrated solid-state Hall-effect switch supports silent, sealed, contactless activation and offers a significant upgrade from failure-prone mechanical switches and provides very low standby current (< 50 μA).The LED driver features low-noise, adjustable, linear drive of up to 150mA into one or more LEDs. An optional external capacitor programs the turn-on/turn-off rate, adding an elegant “theater” effect. It is controlled by the Hall-effect switch and turns on and off in response to a magnet. The Hall-effect switch is omnipolar (responsive to both North and South magnetic poles) and highly sensitive (BOP = 40G) to support a wide range of mechanical configurations and enclosures with various air-gaps and degrees of mechanical misalignment. The AP13568 features selectable output polarity as well as an open drain output for connecting to additional external circuitry.This new device complements Allegro Microsystem’s existing portfolios of LED drivers and Hall-effect switches by adding an external output and micropower operation (<50 μA). It is targeted at consumer electronics, white goods, boats, RVs, motorcycles, and interior and auxiliary automotive lighting applications such as glove boxes, center consoles, vanity mirrors, trunks/boots, truck beds, etc. The on-board micropower regulator permits operation with supply voltages of 7 V to 24 V while providing very low average supply current when the output is disabled. Reliability and EMC performance are enhanced with Zener clamps, output short-circuit protection, thermal shutdown, and reverse-battery protection. Superior Hall switch performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally caused by device overmolding, temperature drift, and thermal stress.The device is available in two versions: the “K” option is an automotive-grade (AEC-Q100) device that operates from -40 °C to +125 °C; the “E” option is for industrial and consumer applications that operate from -40 °C to 85 °C. Both versions feature a RoHS-compliant, thermally enhanced SOIC-8 surface-mount package (designator “LJ”).Ref:KY32-MIC2287CBD5KY32-LM3519MKX-20KY32-HV9921N3