Archive : 25 February 2008 год

AnalogicTech has introduced two mini-Power Management Units (PMUs) that combine three step-down DC/DC converters in a single monolithic IC. Targeted at portable devices with rapidly evolving feature sets, the 3-channel AAT2784 and AAT2785 allow designers to add one 1.5A synchronous step-down converter and two 300mA synchronous step-down converters or one 1.5A synchronous step-down converter and two 600mA synchronous step-down converters respectively, without radically altering their existing core system design or adding numerous discrete devices. Oftentimes portable system designers want to expand the feature set of an existing handset, portable media player or other system, but don’t have the lead time to redesign the system PMU and still meet a rapidly closing market window.

 By offering designers three independently-controlled switching regulators sized to power a processor core, an I/O and a DSP, ASIC or RF circuitry in a single compact package, the AAT2784 and AAT2785 combine the advantages of functional integration, including simpler component selection, reduced BOM, minimised PCB requirements and shorter time-to-market, with the flexibility and electrical performance of a discrete approach. Designed for portable applications, the AAT2784 and AAT2785 operate off an input voltage range of 2.7 to 5.5V. Outputs are adjustable from 0.6V to VIN. Both devices employ a unique low noise architecture that reduces output ripple by 25% and spectral noise by up to 50%. With efficiency levels exceeding 95%, the new devices help reduce power consumption and extend battery life. Quiescent current is a low 50microA per channel. Transient response time is typically < 20micro seconds. Each of the three regulators in the AAT2784 and AAT2785 has an independent enable pin. A high 1.8MHz switching frequency helps minimise the size of external components and reduce PCB footprint. An integrated internal soft start function limits current surge at the input and eliminates output voltage overshoot.

 Both devices also feature over-temperature and current-limit protection. The AAT2784 and AAT2785 are qualified across the -40 C to +85 C temperature range. Both ICs are available in a Pb-free, 16-pin TDFN34 package.

Intersil has introduced an AC-driven Real Time Clock (RTC) devices. The ICs will be designed into a industrial and consumer products, from power meters and security devices to white goods and other high-end appliances that require precise measurement of time. With integrated functionality such as dual alarms, event detection and a “brownout” alert, the ISL12030 and ISL12032 have a broad feature set. Traditionally, RTCs have used an external crystal for timekeeping, and over long periods of time, some crystal-based solutions can accumulate significant errors. The 50/60 Hz AC power ubiquitous to the U.S. and Europe is a new and even more efficient method of providing RTCs with a clock source. By using the AC power line for timekeeping, designers can build devices that ultimately perform more accurately and reliably over the long term and better withstand extreme temperature changes.

 Other features of Intersil’s AC-driven RTCs include an automatic crystal oscillator backup in case the AC line frequency is lost (ISL12032); an integrated trickle charger that allows a rechargeable energy source such as a super capacitor or rechargeable battery to be used as a backup supply; dual alarms for reporting problems with system performance; a power status “brownout” alarm that allows the system to save vital information to memory before a complete power loss occurs; time stamp, which records the time and date of events including power loss, recovery, and tampering, a feature particularly important in metering devices; and a battery status monitor that provides warning if battery voltage drops below a certain threshold. The ISL12030 is available now in an 8 Ld SOIC, and the ISL12032 is available now in a 14 Ld TSSOP.