Power can present problems in modern product designs. Rohde & Schwarz notes that the quality of the power supply is a key factor in the functionality and performance of sensitive electronic circuits—including IoT components with fast digital interfaces, fast memory chips, and sensitive analog circuits—where disturbance signals on the DC power-supply network can lead to EMC problems or impair circuit functionality. To help isolate such problems, the company at DesignCon in Santa Clara in January introduced a power-rail probe that works in conjunction with its oscilloscopes.
Of course, starting with a power supply designed for EMC can help. During MD&M West 2017 in February in Anaheim, SL Power showcased high-performance power supplies for medical applications that meet 4th Edition EMC and DOE Level VI efficiency standards. Other products highlighted here include capacitors, chokes, gaskets, and cases.
MKP X2 capacitors serve EMI suppression applications. Compared with conventional X2 capacitors designed for rated voltages of 305 VAC, these new components offer a higher rated voltage of 350 VAC, making them suitable for EMI suppression in input filters (specifically for applications on the North American market) and output filters of photovoltaic inverters, for example.
The capacitance range extends from 0.47 µF to 10 µF. Even under severe ambient conditions, the new capacitors are characterized by a stable capacitance, as verified in damp heat tests, in which the change in capacitance does not exceed 7.5% (test conditions: 1,000 hours at 85°C with a relative humidity of 85% and a voltage of 330 VAC). The maximum operating temperature of the components is 110°C.
The X2 capacitors are approved in accordance with UL and EN and, depending on the capacitance, are available with a lead spacing of 27.5 mm or 37.5 mm. Both the casing and the epoxy resin sealing material comply with the UL 94 V-0 standard. The capacitors are suitable for applications with higher demands in terms of current capability as well as capacitive power supplies. EPCOS AG
The R&S RT-ZPR20 low-noise power-rail probe offers a bandwidth of 2 GHz and works in combination with the R&S RTE and R&S RTO2000 oscilloscopes. With its low inherent noise and an attenuation factor of 1:1, the R&S RT-ZPR20 probe enables users to measure and analyze in detail even small disturbance voltages using the many functions offered by the oscilloscopes, such as spectral analysis. Thanks to the dynamic range of ±850 mV and large DC voltage offset range of ±60 V, the probe permits analysis of the smallest disturbance signals during power-integrity measurements, even on DC power supplies with a high voltage level.
The R&S RT-ZPR20 also features an integrated high-precision DC voltmeter that allows users to simultaneously measure a power supply’s DC component, irrespective of the offset voltage. This reading and the signal voltage are transmitted to the oscilloscope and displayed, enabling the DC level and ripple to be measured in parallel when qualifying power supplies for highly sensitive electronic components such as CPUs and FPGAs. Users see at a glance whether the ripple voltages lie within the often very tight power supply tolerances.
Rohde & Schwarz
Medical power supplies
The ME Series AC/DC external power supplies are specifically designed to meet challenging home healthcare power requirements for patient-monitoring equipment and respiratory devices that demand a high level EMC, EMI mitigation, and AC input performance. Available in 10, 20, 30, 40 and 60 W, the ME models are fully compliant with Level VI efficiency requirements per U.S. Department of Energy and compliant to IEC 60601-1-2, 4th Edition, for EMC.
In addition, the MB65 Series offers compact 65-W convection-cooled AC/DC internal power supplies that meet power demands for next-generation medical applications including patient-monitoring, surgical, imaging, home healthcare, and laboratory equipment. Measuring 2 x 3.5 x 1.3 inches, the single-output MB65 models with 2MOPP isolation deliver a high level of EMC, EMI, and AC input performance that medical devices require. SL Power
The WE-TPB HV series of current-compensated, three-phase, power-line chokes serves high-voltage applications. This new series guarantees a rated voltage up to 760 VAC, which the vendor reports is 70% more than that offered by comparable products. It was made possible by a patented design using a novel plastic casing, separating strip, and grid plate.
The chokes’ toroids can be made both of MnZn ferrite material as well as of nanocrystalline material—making it possible to achieve high insertion losses even in broadband applications. All insulation materials used in these products are UL 94 V-0 listed. As a measure to enhance the stability on a PCB, the chokes also can be fixed in place with a tapping screw. Typical applications for this series include frequency inverters and high-performance charging stations. Würth Elektronik eiSos
The DCR2U-2000D critical-mission COTS power supply meets the need for reliable DC output from three-phase AC aircraft power over a wide frequency range. The DCR2U Series of COTS power supplies accept inputs of 200 to 375 VDC or 115/200 VAC, three-phase, at 360 to 440 Hz. Custom inputs also are available upon request.
Output power of 2,000/3,000/4,000 W is available from the DCR2U Series, with voltages from 3.3 VDC to 48 VDC. The new 2,400-W DCR2U-2000D power supply is designed to provide +28 VDC at 71 A (2,000 W) and +12 VDC at 33.3 A (400 W). Like other DCR2U power supplies, this unit also has protective circuits, controls, and indicators and wide-ranging operating and storage temperatures. It is designed to meet MIL-STD-810F for shock and vibration and MIL-STD-461E for EMI/EMC.
DCR2U Critical Mission COTS power supplies can be mounted in 19-inch racks and need only 2U (3.50-inch) space. Weight is 28.9 lb. Behlman Electronics
The 3U RackCase PRO is available in standard depths of 9.45, 13.78, and 18.11 inches (240, 350, and 460 mm), with custom depths available to special order. To reduce configuration time and cost, it eliminates the need for drilling when installing chassis trays, brackets, and electro-mechanical components. The design provides all-around access during assembly with top and base covers that slide into place once the unit has been populated with the housed electronics and other components. RackCase PRO has been designed for applications such as audio, broadcast, instrumentation, and other areas where EMC integrity could be an issue; the design ensures conductivity between all component parts of the assembly, providing EMC capability as standard.
The heavy-duty extruded side panels form a rigid structure in conjunction with the front and rear panels and top and base covers. The external face of the side panels features full-length slots for fitting telescopic slides that enable the unit to be withdrawn from a 19-inch rack for easy access. Internally, the side panels have 12 separate channels into which tapped strips or individual M4 captive nuts can be positioned to provide secure mounting points for the housed components. The conductive finish ventilated or plain steel covers slide into dedicated slots; conductive gaskets in these slots prevent movement and ensure conductivity between all components of the assembly. The hole pattern in the ventilated covers provides efficient convection or forced cooling without compromising the EMC integrity. Verotec
EMI-shielding BeCu finger stock gaskets are offered in more than 100 standard profiles. Downloadable interactive drawings allow the user to modify the strips to their exact requirements. Beryllium copper’s mechanical and electrical properties make it a suitable material for EMI/RFI shielding, with greater than 100-dB attenuation. BeCu offers maximum spring properties for strength and fatigue resistance as well as long life without compression set.
Mounting options include snap-on, stick-on, clip-on, track, extrusion, welding, and soldering. A variety of in-house plating options keeps lead times short. In addition, quick delivery programs are in place for both clean-and-bright and tin-plated standard and configured products to support customers’ urgent requirements. An optional DiamondBack textured surface for high-frequency applications is available. Standard gaskets also can be modified, minimizing the cost of producing custom gaskets. Tech-Etch
The medical- and ITE-certified DTM300-D external power supplies offer a choice of class I or class II (no ground connection) inputs and meet Level VI DoE standards for efficiency and off-load power. The DTM300-D is certified to both the medical IEC 60601-1 and ITE IEC 60950-1 standards, making it suitable for a variety of power-hungry medical, industrial, and test and measurement applications.
The convection-cooled DTM300-D is housed in a rugged, vent-free enclosure, measuring 222 mm x 112 mm x 45 mm. AC is applied using the standard IEC 60320-C14 (three-prong) or 60320-C18 (two-prong) connector and DC provided through a 10-pin Molex Mini-Fit connector. Other connectors are available upon request. The adapters also feature over-voltage and over-current protection.
Accepting a 90- to 264-VAC input, the 300-W adapters are available with 12-V, 19-V, 24-V, 28-V, 48-V, and 54-V outputs and can operate in ambient temperatures ranging from -30°C to +60°C (derating linearly to 50% load from 40°C to 60°C). In addition to satisfying DoE Level VI requirements with an average efficiency of greater than 88%, the power supplies have an off-load power draw of less than 0.5 W.
The DTM300 has been certified to IEC/ES/CSA/EN 60601-1 and IEC/UL/CSA/EN 60950-1, and it carries the CE mark for low-voltage, EMC, and RoHS2 directives. All models meet EN 60601-2, IEC 60601-1-2 Ed4:2014, EN 55011/EN 55022 Class B, EN 55024 Class B, FCC Part 15 Class B, and FCC Part 18 Class B emissions and immunity standards. Input to output isolation is 4,000 VAC (2 x MoPP), with a touch current of <100 µA. Class I models are suitable for BF rated equipment with an output to ground isolation of 1,500 VAC. TDK-Lambda Americas
