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EETE APR 2015

Wearable & Implantable electronics Molex already supplies a well-known device manufacturer Temp-Flex MediSpec micro extrusion primary wires for implantable leads. However, when developing a remote battery recharge system for its implantable neurostimulator, the manufacturer required a fine gold wire that could be coiled and implanted to act as a receiver/aerial/ antenna. The solution is based on Molex’s coated pure 3.8 MIL gold wire with 0.8 MIL of ETFE that is then corona-etched so that it can be coiled and potted. One of the downsides to recharging a device wirelessly is that it cannot be implanted more than 2.5 cm beneath the skin. Molex’ Temp-Flex MediSpec micro extrusion primary wires. Inductive charging can also take longer than direct contact due to the lower efficiency. During the development phase of a new rechargeable neurostimulator design, the manufacturer undertook a detailed review process of the inductive charging system to ensure maximum efficiency is achieved – paying particular attention to the coils in the device, which are complex in nature. After completing its review, the company selected Molex’s Temp-Flex coated pure 3.8 MIL gold wire with 0.8 MIL of ETFE that is then corona-etched so that it can be coiled and potted i.e. surrounded by epoxy. The conductor wall thickness, which can go down to .00762mm, meets the tight tolerance requirement for implantable applications. The ETFE insulation is applied by a precise extrusion process that results in superior dielectric integrity compared to other technologies. This process simultaneously encapsulates the wire, providing a consistent and uniform coating. In addition, the process provides a pin-hole-free insulation, resulting in limited risk of conductor exposure and provides a more reliable insulation versus dispersion or enamel coatings. Designers and manufacturers of surgically implantable medical devices require primary wires that meet stringent design requirements and reliability standards. Molex’s ability to coat and etch the gold wire is unique within the industry and proved to be the right choice for manufacturer – several years later Molex is still single-sourced on this project. ARM Cortex-M based MCU draws 35 μA/MHz Staking a claim for the lowest power microcontroller based on the ARM Cortex-M core series, the Atmel | SMART SAM L Family uses one-third the power of alternative offerings and achieves an EEMBC ULPBench Score of 185. With power consumption down to 35 μA/MHz in active mode and 200 nA in sleep mode, the ultralow power SAM L family broadens the Atmel | SMART 32-bit ARM-based MCU portfolio and extends battery life, “from years to decades” for devices such as fire alarms, healthcare, medical, wearable, and devices placed in rural, agriculture, offshore and other remote areas. The SAM L21 combines ultra-low power with Flash and SRAM that are large enough to run both the application and wireless stacks—three features that are cornerstones of most IoT applications. Sampling now, the SAM L21 comes with a development platform including an Xplained PRO kit, code libraries and Atmel Studio support. Atmel www.atmel.com 1.2x1.0x0.3mm crystals cover 36 up to 80MHz Telcona’s 1210 series of ultra miniature surface mount crystals, measuring 1.2x1.0x0.3mm are among the smallest ever realized AT cut crystals in the world, according to the manufacturer. They cover a frequency range of 36MHz up to 80 MHz and come with a frequency tolerance of +/-10ppm. They operate across a temperature range of -40°C to +85°C with a maximum frequency deviation of +/-30ppm. At reduced temperature ranges like -10°C to +60°C a stability of +/-10ppm can be reached. Typical load capacitances are 5-7pF and the series resistance is stated with 200ohm max, but can reach values of 100ohms or less at higher frequencies. Despite their tiny size, the crystals’ parameters can compete with those of much bigger size. The units come on tape and reels with 3000pcs per reel. They are fully RoHs compliant and reflow solderable. Telcona AG www.telcona.com Power management IC targets wearables In a 4 mm² package, ams’AS3701 micro-PMIC includes battery charger circuit, multiple power rails, protection features and I²C interface With an especially small footprint for use in wearables and other spaceconstrained devices, the 2x2x0.4mm chip provides advanced power management functions for products supplied by a single lithium-ion cell. The AS3701’s multiple power rail sources include two 200 mA LDOs, a 500 mA step-down DC-DC converter and two 40 mA (maximum) programmable current sinks. The synchronous step-down (buck) converter, which switches at high frequencies up to 4MHz, only requires a small inductor and a 10 μF output capacitor. The micro-PMIC’s integrated li-ion battery charger can operate in trickle-charge, constant current or constant voltage modes and supplies a maximum charging current of 500 mA. ams www.ams.com 32 Electronic Engineering Times Europe April 2015 www.electronics-eetimes.com


EETE APR 2015
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