Smart Capacitor Switch Reduces Volume of AC-DC Converters by Up to 40%
The MinE-CAP IC recently introduced by Power Integrations dramatically reduces the size of universal input ac-dc converters by enabling the use of different bulk capacitors for low- and high-voltage operation. By limiting the size of the high-voltage bulk electrolytic capacitors required in offline power supplies, this new type of IC makes it possible to reduce adapter size by up to 40%.
The MinE-CAP device also significantly lowers in-rush current, making NTC thermistors unnecessary, and thus increasing system efficiency and reducing heat dissipation. The combined space savings helps designers create compact, easy-to-carry, high-wattage power adapters for smartphones, tablets, and other mobile devices.
The IC leverages the small size and low RDS(on) of gallium-nitride transistors to actively and automatically connect and disconnect segments of the bulk capacitor network, depending on ac-line voltage conditions. Designers using MinE-CAP can select the smallest high-line-rated bulk capacitor required for high ac-line voltages and allocate most of the energy storage to lower-voltage capacitors that are protected by the MinE-CAP until needed at low ac line. This approach dramatically shrinks the size of input bulk capacitors without compromising output ripple, operating efficiency, or requiring redesign of the transformer.
Housed in the miniature MinSOP-16A package, the new devices work seamlessly with Power Integrations’ InnoSwitch family of power-supply ICs with minimal external components. Two initial design example reports (DERs) show how the MinE-CAP IC can be used with InnoSwitch3-Pro PowiGaN devices to create a 65-W USB PD 3.0 power supply with 3.3- to 21-V PPS output for mobile phone/laptop chargers, and a 60-W USB PD 3.0 power supply for USB PD/PPS power adapters (shown in figure at the top of this story).
MinE-CAP MIN1072M ICs, available immediately, are priced at $1.75 for 10 Ku. Learn more about the family and download the reference designs at Power Integrations’ website: https://www.power.com/products/MinE-CAP.
Rugged 1200- and, Yes, 1700-V SiC Schottky Diodes
UnitedSiC announced four new UJ3D 1200- and 1700-V junction barrier Schottky (JBS) diodes to complement its FET and JFET transistor products. They’re the latest additions to the company’s third generation of silicon-carbide (SiC) merged-PiN-Schottky (MPS) diodes. Possessing a VF × Qc figure of merit (FOM) that’s at least 12% to 15% better than the competition, according to the company, these SiC JSB diodes are highly optimized for power-system designs requiring high efficiency and ultra-fast switching speeds. Anticipated applications include fast-charge electric-vehicle (EV) charging access points, industrial motor drives, and solar-energy inverters
The devices have a >8.8-mm clearance between the anode and the cathode, which makes them better at coping with noisy, poorly regulated electrical conditions where voltage transients are likely to be present. In high-current situations, their novel PN junction structure enables the injection of additional charge carriers. These features provide enhanced robustness, allowing the diodes to withstand much higher surge currents than competing devices (up to 12X the rated current).
The additions to the portfolio include a 1700-V, 25A-rated device and three 1200-V devices in 10-, 20-, and 50-A-rated options. Fully compliant with the AEC-Q101 automotive standard, all SiC diodes come in a compact TO247-2L package format and in die form. The UJ3D1725K2 1000-up resale price is $6.47. The UJ3D1210K2, UJ3D1220K2 and UJ3D1250K2 1000-up resale prices are $2.24, $3.39, and $9.55 respectively. Visit www.unitedsic.com for more information.
Buck Converters’ Integrated Ferrite-Bead Compensation Simplifies High-Precision, Low-Noise Designs
Texas Instruments unveiled a new family of low-noise dc-dc switching regulators with integrated ferrite-bead compensation. The TPS62912 and TPS62913 offer noise figures of 20 µVRMS for frequencies ranging from 100 Hz to 100 kHz and ultra-low output-voltage ripple of 10 µVRMS. This gives engineers the ability to remove one or more low-dropout regulators (LDOs) from their designs, reduce power losses by up to 76%, and save 36% of board space. Anticipated applications include high-precision test and measurement, medical, aerospace and defense, and wireless infrastructure.
The new devices offer a simpler alternative to traditional low-noise power-supply architectures, which include a dc-dc converter; a low-noise LDO such as the TPS7A52, TPS7A53 or TPS7A54; and an off-chip filter such as a ferrite bead. By integrating ferrite-bead compensation, the TPS62912 and TPS62913 use the ferrite bead already present in most systems as an effective filter against high-frequency noise, reducing the power-supply output voltage ripple by approximately 30 dB and simplifying the power-supply design.
Pre-production quantities of the 2-A TPS62912 and 3-A TPS62913 are available now, only on TI.com, in a 2- × 2-mm, 10-pin quad flat no-lead (QFN) package. Pricing starts at $1.06 and $1.16, respectively, in 1000-unit quantities. The TPS62912EVM and TPS62913EVM evaluation modules are available for $49. TI expects both devices to be available in volume production in the first quarter of 2021.
To learn how low-noise buck converters work, check out the technical article “Minimize noise and ripple with a low-noise buck converter.” For more information, see www.ti.com/TPS62912-pr and www.ti.com/TPS62913-pr.
Digital Multiphase Controllers and Smart Power Stages Target IoT Infrastructure Systems
Renesas’ second generation of digital multiphase controllers and smart power stages has arrived. Current ratings range from 10 to 1000 A+, and they feature up to 20 phases. As a result, the devices can provide smart, sequenced, multi-voltage power to digital computing loads for advanced CPUs, FPGAs, GPUs, and AI ASICs used in IoT infrastructure systems, data-center servers, storage, optical transport, routers, and switches, as well as computing and 5G wireless infrastructure equipment.
The device family consists of:
ISL6822x, ISL6823x, and RAA2282xx digital multiphase controllers (15 devices)
- Greater scalability and flexibility for adapting to different system requirements—without using phase doublers.
- High-performance digital engine featuring a patented synthetic current control architecture that tracks each phase current with zero latency and significantly reduces TTM with solder-free tuning of any application using Renesas’ PowerNavigator software, the first of its kind for digital multiphase controllers.
ISL993xx and RAA2213xx Smart Power Stages (6 devices)
· 20 to 90 A of maximum continuous current, high integration, and high current-sense capability.
· >30% board space savings over traditional power solutions, which typically employ separate drivers and discrete FETs.
· Smart driver versus a regular driver common in DrMOS devices, enabling the SPS driver to provide a reconstruction of the inductor current by sensing the FETs within the device.
Advanced Development Tools
All of Renesas’ second-generation multiphase power products are supported by the PowerNavigator software platform, a suite of GUI-based configuration and debugging tools. Power designers can easily configure the controller, set the parameters to tune the system, and debug/monitor using the black box, high-speed command logging, and digital test bus features.
The 15 new digital multiphase controllers are available now in 4- × 4-mm to 8- × 8-mm QFN packages from Renesas’ worldwide distributors. For more information, visit www.renesas.com/digital-multiphase-controllers.
The six new smart power stages are available now in 4- × 5-mm to 5- × 6mm QFN packages from Renesas’ worldwide distributors. For more information, visit www.renesas.com/smart-power-stage.
1200-V SiC MOSFET Offers Significantly Lower Losses
Toshiba Electronics Europe launched a 1200-V silicon-carbide (SiC) MOSFET that improves efficiencies and enhances reliability for high-power industrial applications including 400-V ac input ac-dc power supplies, photovoltaic (PV) inverters, and bidirectional dc-dc converters for uninterruptible power supplies (UPS).
Fabricated with Toshiba’s second-generation SiC chip design1, the TW070J120B power MOSFET’s high-voltage resistance, high-speed switching, and low on-resistance characteristics help reduce power consumption and improve power density. In addition, the TW070J120B realizes low input capacitance (CISS) of 1680 pF (typ.), a low gate-input charge (Qg) of 67 nC (typ.), and an RDS(ON) of just 70 mΩ (typ.). When compared with a 1200-V silicon IGBT, such as Toshiba’s GT40QR21, the new device reduces turn-off switching loss by approximately 80% and switching time by around 70%, while delivering low on-voltage characteristics with a drain current (ID) of up to 20 A. The gate threshold voltage (Vth) is set high (in the range 4.2 to 5.8 V), which reduces the possibility of unintended or spurious turn-on (or off). Furthermore, the device’s integrated SiC Schottky barrier diode with a low forward voltage (─1.35 V typical) also helps to reduce losses. Housed in a TO-3P(N) package, the TW070J120B MOSFET is available now. Additional information is available by clicking here. Reference:
1. Toshiba news release on July 30, 2020: “Toshiba’s New Device Structure Improves SiC MOSFET Reliability.”
Application-Specific FETs Tailored to Deliver Optimal Performance
Nexperia has created a new category of MOSFETs, known as application-specific FETs (ASFETs), which feature electrical parameters suited for specific applications. Nexperia’s first families of ASFETs address applications including battery isolation, motor control, hot-swap, and Power over Ethernet (PoE). The improvements offered by these tailored ASFETs varies by the application. For hot-swap applications, they provide a 3X to 5X improvement in safe operating area (SOA). The devices created for motor applications offer maximum current ratings in excess of 300 A.
The ASFET category will be further enhanced with the imminent release of a new family of automotive products with guaranteed repetitive avalanche performance for driving inductive loads. Additional details are available at https://efficiencywins.nexperia.com/efficient-products/optimizing-mosfets-to-fit-specific-applications.html
Nuclear Diamond Batteries Looking More Like Fiction Than Fact
Occasionally, we will run into a story about a “revolutionary” technology that’s too good to be true, but too intriguing to ignore. That was the case with the long-lived batteries supposedly made from radioactive diamonds that we covered in the October 22, 2020 edition of PowerBites.
I was fascinated but skeptical about the company’s claims, so I asked Peter Meyers, a friend of mine who teaches physics at Princeton University, for a reality check. Since he builds dark matter detectors in his spare time (I’m not making this up!), I figured he’d be able to figure out if there was any basis for the company’s claims. Meanwhile, the story triggered the BS detector of at least one sharp-eyed reader named Erik Magnuson, who took the time to share his back-of-the-napkin analysis with me. He wrote:
I did a rough calculation on the amount of power to be expected from Carbon 14 decay in graphite used for moderators in nuclear reactors. I got about 100nW (-70dBW) per gram of carbon*. This is the total decay energy, of which a good fraction escapes with the neutrinos and not the expected electrical energy.
Sounds like BS to me.
*Assumptions; Neutron flux 10^14 n/cm^2-sec irradiation time 30 years.
Interestingly, Peter used the same adjective to describe the alleged capabilities of the device, after providing some slightly more detailed calculations indicating it could take up to 20 tons of retired moderator carbon to produce a few milliwatts worth of power. I’m in the process of translating Peter’s analysis into plain English for a longer follow-up article while I attempt to get someone from Nuclear Diamond Batteries to return my calls for comment. Stay tuned!