Author Archives: steve bush

UK-made Plessey LEDs hit 120 lm/W

November 18, 2014

Plessey has achieved 120 lm/W efficacy and 50% efficiency (power in/out) from its GaN-on-Silicon technology.

“Having developed and put into production the first of our LEDs in 2013, the next step was to demonstrate that the GaN on silicon technology could deliver output performance levels comparable with other LED technologies,” said Plessey CTO Dr Keith Strickland. “Whilst 120 lm/W for an LED may be considered ‘acceptable’ to industry, we must remember that we have doubled our LED light output in the past six months. I see no reason why we cannot reach state of the art in LED die output performance within the next six months.”

“A sustained period of light output performance improvement in the core LED material is due to our holistic approach to LED development; our in-house experts in epitaxy growth, process development and die design all working together,” said operations director Mike Snaith. “Achieving greater than 50% light output efficiency is a superb achievement for the team here in Plymouth.”

The firm’s first 5630 PLCC2 package engineering samples are now shipping, with other package variants available on demand. Blue die with a wavelength of 455nm are also being shipped.

Plessey’s lighting product range will be on show at LuxLive (ExCel London, 19-20 November).

National Gallery gets LEDs

November 18, 2014

Last month it was the Sistine Chapel, and now the UK’s National Gallery has LED lighting.

“A combination of efficient LEDs and a digital control system has achieved 85% energy savings on lighting. The system’s ability to respond to the changing environment allows the Gallery to make use of available daylight and adjust lighting levels around visiting hours,” said Open Technology, which makes the LiGO control system used to dim the LEDs.

Throughout the day, LEDs and external roof blinds automatically adjust according to the amount and angle of sunlight.

Estimated annual energy saving is 765,000kWh, or £53,600 – the Gallery is attempting to reducing carbon emissions by 43% by 2015. Reduced maintenance is said to save a further £36,000.

LEDs are efficient, and don’t produce UV which can fade paintings, but their bumpy spectrum means lighting art with LEDs is not straightforward.

Cray looks at ARM64 for supercomputing

November 18, 2014

Cortex-A57-chip-diagram-LG Cray is evaluating 64bit ARM processors alongside Intel products for its supercomputers, partly under a US Government program called FastForward 2 which asks the firm to explore 64bit ARMs for high performance computing (HPC).

Cray is also working with 64bit ARM chip company Cavium to build processing clusters based on Cavium’s 48 ARM core ThunderX processors to test ARM architectures for supercomputing.

“Our adaptive supercomputing vision centres on system designs that integrate diverse processing technologies into a unified architecture,” said Cray CTO Steve Scott. “We see alternatives such as 64bit ARM, custom ASICs and low-power Intel processors as enabling technologies for certain HPC and analytics workloads.

Cavium has been demonstrating ThunderX silicon at SC14 in New Orleans this week, including it running Red Hat Linux and Canonical Ubuntu Server Distribution operating systems, and Java 8 and Apache Web Server applications.

First 1kV integrated power switch

November 11, 2014

Fairchild has integrated a 1kV power switch, claiming it to be the first in production.

In an ac-dc converter chip called FSL4110LR, the switch is a VDMOS SenseFET (BV_DSS=1,000V).

The IC also includes a PWM with built-in line compensation for a 45 to 460Vac input range, input over-voltage protection, and a safe auto-restart mode for all protection conditions.

Maximum output power is 9W (Vin 85-460Vac), and 4W down to 45Vac

“Fairchild’s power switch is the only solution of its kind that provides ‘abnormal over-current protection, which protects the power converter from transformer abnormalities and is particularly important for smart metering applications,” said Fairchild v-p Gaurang Shah. “With the world’s highest breakdown voltage, the FSL4110LR is an excellent solution for any designer implementing flyback converters that need to meet three phase input voltage or unstable single phase input voltage requirements.”

PWM operating frequency is 50kHz within a few percent right across -40 to +125C, with random fluctuations to reduced measured EMI, plus there is a burst mode. Power can come from self-biasing or from a bias winding.

Current limiting is pulse-by-pulse, and thee are further protections for: overload and over-hot die (with hysteresis). Under-voltage lock-out is included.

Applications are expected in smart meter, appliance and industrial systems.

Fairchild is exhibiting the switch at Booth A4.506 at Electronica 2014 in Munich.

Glass seals MEMS for harsh environments

November 11, 2014

Glass with hermetic conductive through-hole vias can seal MEMS for 3D wafer-level chip size packaging (WLCSP), according to Schott of Germany.

Its product is called Hermes.

“Through-glass via substrates enable fully gastight and therefore long-term robust enclosures for MEMS devices,” said Schott. “The fine pitched vias allow the reliable conduction of electrical signals and power into and out of the MEMS device. Since Hermes can be placed directly under the silicon MEMS, it makes miniaturised, fully hermetic 3D WLCSP possible.”

The firm is aiming at industrial, medical and radio-frequency applications in harsh environments, claiming its glass can exceed the performance of ceramic and silicon enclosures exposed to mechanical, thermal and chemical stress, for example withstanding body fluids and repeated sterilisation in medical applications.

“Thanks to the low dielectric constant of glass and the possibility to use highly conductive via materials, Hermes wafer packaging offers excellent RF performance,” it added. “And the optical transparency of the glass wafer enables better processing and quality control during the production process of a MEMS device.”

Wafer-scale anodic bonding with silicon, glass frit and solder is possible.

There are three glass options: Borofloat 33 floated borosilicate glass, AF 32 eco 33 alkali-free flat glass, and D 263T eco borosilicate glass (see table below).

Wafer
Wafer thickness	500±20μm (350μm minimum)
Wafer size	4, 6, 8inch
Contact via pitch	250μm	200μm	150μm*
Contact via diameter	100μm	80μm	50μm*
Via density	50k* (6″), 100k* (8″)
Via materials	Tungsten (W) – combined with Borofloat 33 and AF 32 eco 33 Iron Nickel (FeNi) – combined with D 263 T eco (others available on request)
Hermeticity	[≤ 1 × 10^–9 Pa • m³/s], [≤ 1 × 10^–8 mbar/s], [≤ 1 × 10^–8 atm cc/s]
Glass
Glass material	Borofloat 33	AF 32 eco 33	D 263 T eco
Coefficient of thermal expansion	3.25 x 10^-6/K (match to Si)	3.2 x 10^-6/K (match to Si)	7.2 x 10^-6/K
Dielectric constant @ 1MHz	4.6	5.1	6.7
Refractive index (@ 600nm)	1.47	1.51	1.52

* in development

XMOS adds industrial comms development kit

September 25, 2014

Xmos has announced development boards for its fast and novel xCore-XA microcontroller, that includes an ARM Cortex-M3 alongside its unconventional low-latency 32bit multi-core processor architecture – invented to provide fast deterministic interfacing without interrupts.

The first products aimed at flexible industrial ‘field bus’ communication.

“There are a plethora of field bus standards. A lot are emerging, and this is where the flexibility of software-defined interfacing is really useful,” Xmos product manager Peter Tasker told Electronics Weekly.

This is not the first time Xmos has tacked field bus with a development kit – there was one early in 2013 (IS-BUS sliceCARD), but this is the first to include the Cortex-M3 extension the firm announced this time last year.

It bought the Cortex-M3 in from Energy Micro (even as Energy was acquired by Silicon Labs), along with a handful of Energy’s famously low-power peripherals – including UART, GPIO and USB.

While incorporating hard peripherals went against the grain at Xmos, it gave the firm a chip that could sleep at under 1µA, clip along at 50Mips for 10mA on the ARM core, then fly instantaneously to 500Mips by engaging the proprietary xCores – all for 50mA.

“The ARM can do the easy stuff and the heavy-lifting is done by the xCores,” said Tasker.

For industrial use, xCores can run the lower levels of Ethernet and CAN stacks, for example, while the Cortex-M3 handles the upper layers. Libraries are available to aid communication between the dissimilar cores, and there are stacks for CAN and Ethernet on the way.

“Most field busses are built on Ethernet and CAN. We don’t intend to develop loads of stacks. We will have some core stuff like Ethernet and CAN, and we might partner with third-party industrial stack providers to offer their products on our silicon,” said Tasker.

And if a customer wants to develop custom lower stack levels for a different interface?

According to Tasker: “It is pretty easy to implement the low level on xCores – you don’t have to write interrupt service routings. I wrote a DMX 512 [LED lighting] controller in a few hours.”

Aren’t there already plenty of microcontrollers around with Ethernet and CAN interfaces?

Tasker questions their reliability and determinism.

“When CAN is a hard peripheral, the peripheral does the CRC [cyclic redundancy check] and passes only the packet on to the processor. In a bridge, we want to preserve CRC from end to end, all the way from CAN to Ethernet,” he said, adding: “We have implemented the AVB bus, which proves we can do determinism.”

AVB – audio video bridging – is a set of IEEE standards with rather touchy timing constraints – so much so, and in acknowledgement that the standards are reaching beyond audio and video, that the IEEE AVB task group was renamed the ‘Time-sensitive networking task group’.

For field bus there is a pair of development boards – the general-purpose xCore-XA development module – which plugs into an ‘application specific baseboard’ – in this case dedicated to industrial communication and incorporating the Ethernet PHYs. Later baseboards will be aimed at other applications.

The development module is stripped down compared with xMos’ earlier offerings.

“This is really for hard-core engineers. We have taken off some twinkling lights and push buttons in favour of giving users access to all the I/O without multiplexing to give them a flashing lights demo,” said Tasker. “There are a couple of LEDs to see if it is booting, and a reset switch.”

The top side of the general-purpose module PCB has only the components that would be needed in a final system. Underneath are development components such as the two hardware debuggers – an in-house xTag-3 for the xCores and a Segger J-Link OB for the M3. Connections are though USB and 0.1inch headers – which is still the favoured header pitch, according to Tasker.

This plugs into the baseboard – which is physically large to improve stability when heavy field bus cables are attached.

Layout is such on the general-purpose board that users can make custom baseboards using double-sided PCB rather than four layers.

Xmos also sees small interface cards being attached to the top of the general purpose module, and Tasker has some interesting plans in this direction, which Electronics Weekly cannot yet reveal.

Software tools include an integrated development environment on which ARM and xCore C-code is displayed simultaneously, and the debug tools also display simultaneously. “All these debug tools are free, and really powerful,” claimed Tasker.

Another tool, xTime composer, does static timing and has a real-time oscilloscope-like display.

Board will be available in December from distributors including Digi-Key. For an early glimps, there will be some demonstrations at ARM techCon in Santa Clara next week.

xCore-XA microcontroller modes at a glance

Shut-down: 100nAtyp, 160us wake on GPIO or reset
Deep-sleep: 1uAtyp, 2us wake on RTC or peripherals
Processor-sleep: 50uAtyp, peripherals operate autonomously
Low-power: 10mAtyp, 50Mips

Performance: 50mAtyp*, xCores engaged for 500Mips

* Assumes 3.3V source supply and dc-dc conversion loss

Dev kit for TI one-chip IoT W-Fi node

August 11, 2014

CC3200 LaunchPad is an internet-of-things (IoT) development kit for Texas Instruments’ CC3200 one-chip Wi-Fi microcontroller+baseband.

The chip has two ARM cores: One within a Wi-Fi network processor for running a 802.11b/g/n Wi-Fi stack (see below), which leaves the second, an 80MHz Cortex-M4, available for application processing.

To this, the kit adds temperature sensors, a 3-axis accelerometer, LEDs and push-buttons, and it comes with driver support and an software development kit (SDK) with 40 applications for Wi-Fi protocols, internet applications and MCU peripheral examples, together with user guides, design files and API guides.

For those wishing to put a Wi-Fi network processor on their own microcontroller, CC3100 BoosterPack is available.

“It can run on two AA batteries for over a year which, for the first time, brings embedded Wi-Fi capabilities to battery-operated end-equipment,” said Farnell, which is stocking both development kits.

An emulation accessory – CC31XXEMUBOOST – is a board for flashing updates to the CC3100BOOST.

CC3200 network processor

As well as aan ARM core, this includes an 802.11b/g/n radio, baseband, and MAC with a crypto engine256bit encryption.

CC3200 supports Station, Access Point, and Wi-Fi Direct modes, as well as WPA2 personal and enterprise security and WPS 2.0.

TCP/IP and TLS/SSL stacks, HTTP server, and multiple Internet protocols are embedded.

power management sub-system includes integrated dc-dc converters, and enables low-power modes such as ‘hibernate with RTC’ requiring less than 4μA.

Bristol University to extend software-defined networking

August 11, 2014

Professor Dimitra Simeonidou

Professor Dimitra Simeonidou

Software defined networking (SDN) is the key to network convergence, claims the University of Bristol, part of a £12m consortium developing it.

The project, ‘Towards Ultimate Convergence of All Networks’ (‘Toucan’), involves a technology agnostic architecture that which will “facilitate optimal interconnection of any network technology domains, networked devices and data sets with high flexibility, resource and energy efficiency, and will aim to satisfy the full range of quality of service [QoS] and quality of experience [QoE] requirements”, said the University.

Toucan will add to SDN what Bristol describes as technology-specific interfacing and resource description followed by infrastructure resource abstraction, virtualisation and programmability.

Such a network, devices are programmable and interoperable.

“Toucan will revolutionise the way we build and operate communication networks in a similar way that computer networks and more recently mobile terminals were transformed from platform-oriented to platform-agnostic solutions, for example through Linux and Android, and will drive towards commoditisation of network devices,” said project lead Professor Dimitra Simeonidou.

“In that sense, Toucan will deliver a ‘network technology USB’ which will make any networked technology and device discoverable, describable and interoperable within any network infrastructure. Any new technology generation, regardless of whether it is wired or wireless, will connect to the Toucan network in a plug-and-play fashion.”

£6m over five years comes from the Engineering and Physical Sciences Research Council (EPSRC).

Project partners include: Professor Dimitra Simeonidou and Professor Mark Beach – University of Bristol; Professor Harald Haas – University of Edinburgh; Professor Steve McLaughlin – Heriot-Watt University; Professor David Hutchison – Lancaster University.

External consortium partners are: Bristol City Council, Broadcom UK, BT, Janet UK, NEC, Plextek, Samsung, and the Technology Strategy Board, who collectively are committing over £3.6m. Another £2.4m will be contributed by the participating institution through PhD studentships and research equipment funding.

300kW SiC half-bridge offers 99% efficiency

Silicon carbide is a route 99% efficiency in induction heating drivers, claimed Cree as it introduced a 300A, 1.2kV half-bridge module.

Bolting straight into a industry-standard 62mm footprint, it includes two 5mΩ SiC mosfets and two SiC free-wheeling Schottky diodes, that drop 1.7V at 300A.

“The power module is pin-compatible to 62mm half-bridge modules, including IGBT modules rated at 450A or more, allowing designers to evaluate the module’s capabilities,” said Cree.

Dubbed CAS300M12BM2, price is $451 each for 1,000-unit quantities.

Other applications foreseen are: solar Inverters and variable-frequency motor drives.

A matched driver board (CGD15HB62P) is also available, which will operate the half-bridge on DC bus voltages up to 900V at up to 32kHz – or 64KHz with some component swaps.

It is completely isolated and includes everything required to interface microcontroller PWM waveforms to the half-bridge. It does need a 15V power rail on the microcontroller side.

A gate driver reference design is also available.

Vishay turns to nitride for high-power chip resistors

Vishay is using aluminium nitride substrates to achive 2W and 6W power handling in 1206 and 2512 chip resistors, respectively.

Called PCAN, they also have enlarged backside terminations to reduce thermal resistance between resistive element and PCB solder joint.

“The devices provide four times the power handling capability of commercial chip resistors,” said the firm, which is aiming them at power supplies for industrial, telecommunications, test, measurement, medical, military and aerospace.

They have ±25ppm/°C and 0.1ppm/V coefficients, and laser-trimmed tolerances down to ±0.1% over -55°C to 150°C.

Values between 30Ω and 175Ω are available with 75 to 200V ratings.

Flame-resistant in accordance with UL 94 V-0.

Pb-free wrap-around terminations are standard, with Pb-inclusive, wire-bondable gold, and epoxy-bondable (glueable) gold options.