Power Management I Product News
Autozero Op Amp extends system uptime and improves sensor performance
Maxim Integrated Products has introduced the MAX44251, a 20V, ultra-precise, low-noise dual op amp that extends maintenance system uptime and maximises sensor performance. Proprietary autozero technology enables continuous self-calibration which, in turn, ensures system accuracy over time, temperature, and power-supply variations. The precision (< 6µV initial offset) over the wide 2.7V to 20V operating range has improved system accuracy and minimizes errors during signal conditioning. The accuracy over the extended voltage range also makes the op amp more flexible for a range of designs and applications. The MAX44251 provides RF immunity filters
that remove the unwanted RF signals often found in industrial and medical applications. According to Maxim this efficiency and associated power savings come with no sacrifice in performance. The low 1.15mA current consumption per channel offers 10MHz gain bandwidth and the industry’s lowest noise (5.9nV/vHz input referred voltage) for a high- voltage autozero op amp. The device is suited for high-voltage applications that require ultra-low noise and ultra-high DC precision, such as interfacing with pressure sensors, strain gauges, precision weight scales, and medical instrumentation.
The MAX44251 has near-zero DC offset and
drift through the use of a proprietary autocorrelating, zeroing technique. Autozeroing constantly measures and compensates the input offset, eliminating drift over time and temperature and the effect of 1/f noise. The low-
DC-DC converter looks to meet the need for increased power density and low noise
Enpirion has unveiled the newest member of its power IC portfolio targeted at embedded computing as well as solid-state drives (SSDs). The EN5339 3 Amp power system-on-a-chip (PowerSoC) integrates the controller, power MOSFETs, compensation network and inductor into one highly compact solution that significantly reduces the traditional engineering analysis and design effort associated with discrete DC-DC converter designs. The EN5339 fits into a 55 mm2
input offset voltage of 6 V (max) and voltage temperature drift of 19nV/°C (max) offer precision across -40°C to +125°C. Autozero offset calibration also eliminates the effects of power-supply variations and even common- mode variations.
The MAX44251 high-speed (10MHz)
autozero op amp also adds high-precision capabilities. The device’s power-supply rejection ratio (PSRR), common-mode rejection ratio (CMRR), and large-signal voltage gain (AVOL) exceed 135dB at +25°C. This accuracy over its wide voltage range increases the flexibility of the design and minimises the errors during signal conditioning.
The MAX44521 is rated over the -40°C to +125°C temperature range and is available in 8- pin SOT23 and µMAX packages.
Maxim Integrated Products | www.maxim-ic.com
New dual output synchronous step-down controller from Linear
Linear Technology has introduced the LTC3838, a high frequency controlled on-time dual output synchronous step-down DC/DC controller with differential output voltage sensing and clock synchronization. The controlled on-time, valley current-mode architecture enables a very fast transient response by increasing its operating frequency during a transient event, enabling the LTC3838 to recover from a large load step in only a few clock cycles. The operating frequency is selectable from 200kHz to 2MHz or can be synchronized to an external clock. A low 30ns minimum on-time allows for a high step-down ratio power supply at very high operating frequencies. The LTC3838 operates over a 4.5V to 38V input voltage range, encompassing a wide variety of applications including most intermediate bus voltages. Strong onboard N- channel MOSFET gate drivers allow the use of high power external MOSFETs for output currents up to 25A per channel, at output voltages ranging from 0.6V to 5.5V, making it ideal for point-of-load requirements. The LTC3838’s differential amplifier provides true remote output voltage sensing of both the positive and negative terminals, enabling high accuracy regulation independent of board IR losses (up to ±500mV). The output current is monitored by sensing the voltage drop across the
with a 1.1 mm profile. High-density embedded computer-on-modules, in particular, require this small area and often a low profile to enable bottom-side PCB mounting. Keeping up with the demands of embedded, industrial and storage applications, the EN5339 enables a 20 percent solution footprint reduction and 40 percent lower profile compared to previous Enpirion 3 Amp products. “We continue to optimise solution size and cost without compromising the high performance and simplicity of design,” said Mark Cieri, Enpirion’s director of marketing and business development. “I was told just last week by a hardware engineering manager at a leading European embedded computer maker that his most difficult design challenge was fitting both the processors and discrete DC-DC converters onto the same card.” The EN5339’s low profile, combined with a solution footprint 75 percent smaller than many competitive products, enables highest-density computer-on-modules, densely stacked multi- board design and mounting on the backside of PCBs, which is often necessary.
Fully validated and proven PCB layout and design files are provided, enabling customers nearly 100 percent first-pass reported success. In addition to EN5339’s competitive cost, it
requires fewer external components (typically 3 to 6). A low ripple (6 mV) and EMI eliminate the need for external noise filters, while its thermal performance and construction negate the need for heatsinks.
The EN5339 achieves up to 96 percent efficiency.
Enpirion high-efficiency devices are truly industrial graded and do not require load de- rating at 85°C ambient temperature. PowerSoCs are specified, simulated, characterized, validated and manufacturing-tested as a complete power system –which, when coupled with tightly controlled IC manufacturing processes and fewer total components, yields enhanced reliability. The EN5339 device is now sampling, with volume production by December 2011.
Enpirion | www.enpirion.com
GAÏA Converter releases new family of high input voltage DC/DC converters
output inductor (DCR) for highest efficiency or by using a sense resistor for extra precision. Additional features include an onboard bias voltage LDO, soft-start or tracking, adjustable current limit, overvoltage protection, current limit foldback and external VCC control. The LTC3838 offers total regulation accuracy and is specified to account for all error sources including line, load and differential sensing. The LTC3838 total differential output voltage accuracy is +/-0.25% at 25°C, +/-0.67% from 0°C to 85°C and ±1% maximum DC error over the full -40°C to 125°C operating junction temperature range. The LTC3838 is available in thermally enhanced 5mm x 7mm QFN-38 or TSSOP-38 packages.
Linear Technology | www.linear.com
GAIA Converter, a specialist supplier of power supplies, has released a new family of high input voltage DC/DC Converters targeting Avionic, Aerospace, Military and Missile applications. The MGDS-75-S series have an input voltage range of 155-480V, making them suitable for 270V applications such as those needing to meet MIL-STD-704E/F requirements, or for use with Power Factor Corrected front end converters such as Gaia’s HGMS-350 series. The family consists of 5 individual single output models offering 3.3V, 5V, 12V, 15V and 26V outputs, each capable of delivering up to 75W in the industry standard Quarter Brick footprint of 57.9mm x 36.8mm x 12.7mm. The units have ±10% voltage trim capability, meaning for example that 28V applications can also be catered for using the 26V nominal device. Efficiency levels are as high as 92%, and the
standard operating temperature range is -40°C to +105°C case temperature, with an option available for -55°C start up operation if required. The units incorporate a complete suite of protection functions such as under voltage lockout, over voltage protection, current limit & over temperature protection, and all units are permanently short circuit proof. Designed for high reliability applications, the MGDS-75-S does not use optocouplers in the
STMicroelectronics launches new power-management family
STMicroelectronics has announced the rolling out of a new family of hot-swap power-management devices that will help reduce ownership costs for important equipment such as storage devices, computers, USB accessories, enterprise systems, appliances and home electronics. The first two devices in the family provide smart, cost-effective and space-saving over-voltage and over-current protection for 5V and 12V electronics. The STEF05 and STEF12 are electronic fuses in 3 x 3mm IC packages, which can replace larger conventional fuses or other protection devices
26 December 2011/January 2012
such as transils or diodes. Unlike fuses, they do not cut the power suddenly or require replacement after actuating, thereby helping to improve equipment uptime and availability while also reducing maintenance costs. Compared to transils or diodes, the new electronic fuses enable versatile and simple programming of protection parameters.
If a fault occurs, the electronic fuse restricts
the current supplied, hence protecting the connected circuitry, and ultimately turns the protected equipment off if the fault persists. It
Components in Electronics
can be reset by a signal from the system or by restarting the power supply. The device provides a signal when it is intervening, allowing the system to generate a warning. If the fault persists after the reset, the fuse immediately limits the current and turns off again to protect the circuitry.
The devices also integrate circuitry that limits voltage fluctuations applied to the protected load, and programmable start-up time, allowing use in hot-swappable modules for equipment such as enterprise servers, storage or telecom
systems. Hot swapping allows faulty modules to be replaced without fully powering down the system, which minimizes disruption to services. Major features of STEF05 and STEF12: suitable for use with 5V or 12V power supplies; current limit programmed by external resistor; output voltage slew rate adjustable with small external capacitor and an output voltage clamp.
STMicroelectronics | www.st.com www.cieonline.co.uk
feedback loop, and operates using a fixed switching frequency of 500kHz. They can be operated at zero load, and employ soft start circuitry which allows for current limiting, and eliminates inrush current during start up. Multiple devices can be synchronised directly together to force a single overall switching frequency, or can be connected to an external frequency source. For applications requiring increased power levels, an optional parallel pin is offered for direct connection of multiple modules ensuring accurate current share. All GAÏA converters are designed and manufactured in-house in France using fully automated manufacturing and test equipment. GAÏA Converter has offices in France, Germany, the USA and distributors worldwide.
GAÏA Converter | www.gaia-converter.com
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