Power Electronics

Data Points

Next-Generation Reserve Micro Batteries

To commercialize advances made in nanotechnology by scientists at Bell Labs, mPhase Technologies (Norwalk, Conn.) has formed a partnership with the research and development arm of Lucent Technologies. Exploiting the advances in nanotechnology and materials, the two partners are working closely to create a powerful next-generation of reserve micro batteries. Conventional batteries have electrochemical reactions proceeding at some level all the time, even when batteries aren't in use. Thus, these batteries degrade over time.

By using the Bell Labs technique to isolate the liquid electrolyte so electrochemical reactions don't take place until power is needed, nanograss-based micro batteries may be ideal for long-term, higher capacity battery applications, especially where bursts of power are needed, said Steve Simon, executive vice president of R&D at mPhase. For instance, sensors out in the field that only need a lot of power when they detect something and need to transmit the information as a wireless signal are candidates for this type of battery. Other applications that could exploit the longer shelf life and reduced battery weight include military, security and emergency services.

Aiming to bring this technology to the marketplace within the next 12 to 18 months, mPhase is racing to demonstrate the first prototypes by this fall. The nano power cells under development will use the super-hydrophobic effect of liquids to permit precise control and activation of the batteries on demand. The droplet sits above the tubes with little or no interaction with the tubes themselves. By careful engineering, the droplet can be made to fall within the space between the tubes encountering a greatly increased surface area and interacting with the tubes themselves to cause a current to flow. The drop can be engineered to occur upon a variety of stimuli, such as voltage, RF and/or others.

According to mPhase, advantages of a nano battery include long shelf life of greater than 25 years, thin form factor with < 1-mm thickness, ramp up to full power in less than 1 ms, compatible with semiconductor processing, high power and energy density, and range of chemistries. The initial zinc chloride-based nano power cell under development is being optimized to offer an energy density of 50 Wh/kg and a power density of 60 W/kg. The open circuit voltage is 1.65 V with an operating temperature range of -40°C to 50°C (see the table).

For more information, visit www.mphasetech.com.

1350-W Rectifier in 1.5-U Package

The TCR-1350 rectifier module delivers up to 1350 W in a 1.5-U profile, maintaining full power output with no derating up to 65°C. Measuring 2.5 in. × 5.2 in. × 11.75 in., the rectifier achieves 9 W/in3 and greater than 90% efficiency under high line conditions. It is offered with outputs ranging from 20 V to 28 V or 50 V to 56 V with operation from 100-Vac to 240-Vac input.

Open Circuit Thickness Energy Density Power Density Temperature Range Self Discharge
V Wh/Kg Wh/L W/Kg W/L °C %/Year
AA Primary Cell 1.65 14 mm 110 250 20 40 -40 +50 10
Nano Power Cell (estimated) 1.65 600µm 50 120 60 30 -40 +50 Reserve
Nano Power Cell - Advanced Reserve (estimated) 1.65 600µm 75 175 90 1 90 -40 +50
Lithium Reserve Microcell* 3.6 3.2 mm 92 12 -45 +60 Reserve
Lithium Reserve Microcell* 3.6 7.0 mm 50 81 -45 +60 Reserve
*ATK Power Sources Center

The units operate in stand-alone or paralleled for higher power levels. In one application, 16 of the rectifier modules were combined for a total output power of 22,000 W. The TCR-1350 can be deployed as part of the TCPR-3U Power System, which adds low-voltage disconnect, a controller card for battery management and a communications interface. The TCPR-3U supports up to four TCR-1350 modules with nonredundant parallel operation or N+1 redundancy with hot swap of individual modules.

For more information, visit www.tectrol.com.

3-in. × 5-in. Supply Delivers 175 W

Lambda's NV-175 quad output power supply produces 175 W of total output power using a 3-in. × 5-in. × 1.25-in. open-frame package. This switch-mode supply employs a multiple resonant topology (MRT) that uniquely uses synchronous rectification to achieve efficiencies up to 90%.

The power supply provides between one and four outputs, available initially from 0.9 V to 15 V at currents up to 25 A. It's also available with a fifth output rated at 5 V and 2 A. Unlike most 3-in. × 5-in. switchers, which specify an unpopular 10% minimum load on the outputs, the NV-175 has no minimum load requirements.

The supply also features power factor correction (PFC), remote on/off and power good signals. Unique for this class of product, the NV-175 has EN60601 medical approval combined with EN55022 Level B conducted emissions as well as EN61010 and EN60950 approvals.

At the heart of this power supply design is the multi-resonant topology, which gives a 5% improvement over more traditional ac-dc power supplies. The MRT uses closed-loop control of the main outputs, a single conversion stage and auxiliary channels using high-efficiency, synchronous dc-dc post regulation.

The topology also uses smaller, lower-loss output inductors, along with a ferrite boost choke wound with Litz wire. Improvements in multilayer ceramic and functional organic polymer capacitors enable the use of simplified filter circuits without inductors, increasing efficiency and reducing size. Silicon carbide Schottky diodes in the PFC circuit provide a further 4% improvement in efficiency. The NV-175 is priced at $148 each in small quantities.

For more information, visit www.lambdapower.com.

Power Supply Controller

Linear Technology's LTC3738 Intel VRM10 Pentium 4 power supply controller features precision current balancing and remote thermal monitoring to optimize power supply thermal performance for maximum processor speed. This PolyPhase multi-channel step-down dc-dc synchronous MOSFET controller is scalable from three to 12 phases for load currents ranging from 60 A to 200 A.

The LTC3738 is compliant with Intel's VRM10/VRD10 and VRM9 CPU power supply specifications. Each controller chip integrates three synchronous MOSFET drivers. Equivalent competitive solutions require four power control ICs and a temperature monitoring IC, while the LTC3738 incorporates all these functions. Housed in a 7-mm × 5-mm QFN, the LTC3738 is priced at $4.65 each in lots of 1000.

For more information, visit www.linear.com.

BGA Power Converter Drives High-Power LEDs

Vishay Intertechnology's complete constant-current-source module co-packages all the components needed to drive power LEDs rated for operation at or above 300 mA. An addition to the FunctionPAK family of dc-dc converters, the FX5959G701ADJ converter comes in a 15-mm × 15-mm × 3.2-mm BGA. It connects directly to the LED and a low-voltage source without requiring any extra components.

Intended for use in end products, the module also can serve as a laser diode driver and to drive the ultraviolet LEDs used in printers to dry ink quickly.

Rated for maximum outputs of 15 W and 2.5 A, it features a 2.5-V to 6-V input range that accommodates various battery configurations and chemistries. High-efficiency is delivered over a large load range, with synchronous-rectified PWM mode operation under full load and externally controlled pulse-skipping mode (PSM) under light load. Now sampling, the FX5959G701ADJ is priced starting at $7.50 each in lots of 10,000.

For more information, visit www.vishay.com.

Power Management Guide For FPGAs

A design guide from National Semiconductor includes selection tables linking popular Xilinx FPGAs with corresponding National Semiconductor voltage regulators, voltage supervisors and voltage references that meet the power management requirements of each FPGA. It also includes schematics for seven complete reference designs, with fully optimized power supplies for each of the Xilinx FPGAs featured in the guide.

In addition, National offers an expanded Web page that recommends National's power management, thermal management, interface, networking and Bluetooth wireless products for use with Xilinx FPGAs.

For more information, visit www.national.com/appinfo/power/xilinxfpga.html

Power System Targets Telecom Networks

The Signature Power System from Transistor Devices integrates ac-dc, dc-dc and dc-ac power components into one cabinet to achieve a modular, scalable, tailored solution, including N+1 parallel redundancy. Suitable for wireless network applications, the power system lets network engineers customize their power systems by adding rectifiers, converters and inverters to meet site requirements without costly NRE or long lead times.

Systems range from 25 A to 2000 A and offer battery-backed +24-Vdc, -48-Vdc, 110-Vac, and 220-Vac operation. Multiple power distribution panels and low-voltage disconnect options are available. The entire power system is then managed by the ICON controller, which needs no proprietary software or expensive upgrades.

More details are available at www.tdipower.com.

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