Power Electronics

Controllers Extend Multiphase Benefits to More Applications

Recent introductions of multiphase power controllers include the familiar single-output buck converters for powering CPU. However, they also include multioutput and boost variations that deliver the small design size desired in other types of applications.

From Intersil, the ISL6217A is a multiphase CPU core controller with integrated half-bridge gate drivers. The controller provides a precision voltage regulation system for advanced Intel Centrino platforms in notebook computers. With integrated drivers, the ISL6217A requires less board area than external gate drive solutions.

The controller, which provides single- and/or dual-phase power conversion, offers a choice of "lossless" current sensing or optional discrete precision resistor current sensing. Other features include internal gate drive and boot-strap diodes. The controller also regulates core voltage to ±0.8% system accuracy over temperature and offers 6-bit microprocessor voltage identification input (VID), and programmable droop and core voltage slew rate to comply with the Intel Centrino specification.

The ISL6217A is available now in a 38-pin TSSOP package. The suggested price in 10,000 unit quantities is $3.50 for each IC. Additional information is available at information, visit www.intersil.com.

Semtech’s SC2441 is a low input voltage, 2-phase synchronous step-down controller with an integrated step-up converter. The device is capable of generating three output voltages to meet the multi-output power requirements in telecommunications and networking systems. The SC2441 operates from an input voltage as low as 1.8V (minimum 1.5V) and generates an output as low as 0.5 V.

The dual-phase, step-down controller can be configured to supply two individually controlled and regulated 20-A outputs, 180 degrees out-of-phase or, alternatively, the two phases can be interleaved into one low-ripple 40-A output. Moreover, the SC2441’s integrated boost step-up switching regulator offers an additional output or can be used to generate a bias supply to drive the gates of MOSFETs at low input voltage conditions. Other SC2441 features include individual, per-phase soft-start and overload timers; programmable fixed switching frequency up to 1 MHz; up to a 90% duty cycle and an individual enable pin for controlling power sequencing of each phase. The device also incorporates the company’s Combi-Sense technique for providing lossless peak current mode control, eliminating the need for an external current sense resistor.

Offered in a 28-pin, lead-free TSSOP, the SC2441 controller is available now and is priced at $2.95 each in 1,000-piece lots. For more details, see www.semtech.com.

From Linear Technology, the LT3782 is a step-up dc-dc controller with 2-phase operation to deliver high output power using only two inductors, eliminating the need for power and current sense transformers. The LT3782 can regulate a 50-V output at 4-A load current with 96% efficiency from an input source ranging from 10 V to 36 V. The 2-phase operation minimizes input and output ripple currents and reduces the value requirements of both the input and output capacitors. With 10-V gate drive and 4-A peak drive current, the LT3782 can drive industrial grade high-power MOSFETs at high efficiency. Furthermore, with adjustable slope compensation, time delay and undervoltage lockout, as well as synchronous operation and clock synchronization, a power supply designer can tailor the circuit to achieve optimum performance. Applications for the LT3782 include automotive, avionics, telecom and base stations.

The LT3782 uses a constant frequency (150 kHz to 500 kHz) current-mode architecture to improve both line and load regulation, reduce the size of inductors and capacitors and provide a precision pulse-by-pulse current limit. For synchronous applications, the LT3782 provides synchronous gate signals with programmable falling edge delay to avoid cross conduction when using external MOSFET drivers. The LT3782 operates from a wide input range of 6 V to 40 V, producing a maximum output voltage that is dependent on external components. Offered in a thermally enhanced 28-lead SSOP, the LT3782 is priced at $4.70 each in lots of 1,000. For more, see www.linear.com.

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