DC-to-DC Converters

The increased use of digital technology has brought equally challenging requirements to dc-to-dc conversion. “As the processing demands in computers and gaming consoles increase, CPUs require accompanying solutions that can respond quickly and efficiently to shifting power needs,” observes John Blake, product line manager, Power Management, Analog Devices. These increased requirements apply to more than just computer products. According to the market research firm Venture Development Corp. (VDC), shipments of dc-to-dc switching regulators in the American market for PC and office automation account for 30.2 percent of the recent shipments but consumer electronics accounted for 28.2 percent and telecom products another 22.6 percent. According to Mohan Mankikar, president, Micro-Tech Consultants, dc-to-dc converter growth will occur in the captive portion of the market:

With modern dc-to-dc ICs, it is not uncommon to achieve efficiencies in the area of 90 percent plus.

PROGRAMMABLE SYNCHRONOUS BUCK CONTROLLER

Analog Devices’ ADP3192 is a synchronous buck controller optimized for converting 12V dc into the core output voltages (between 0.5 and 1.6V) required by high-performance processors. The 8-bit programmable 2 to 4-phase controller uses an enhanced pulse-width-modulation (EPWM) architecture to provide fast response time and power supply regulation. The unit uses a non-linear control technique to identify the amount of current required from the power supply. Depending on system requirements that can increase rapidly when supporting high-resolution graphics, this load-step continually shifts. The controller acquires an 8-bit voltage identification (VID) code directly from the processor. The ADP3192’s selectable 2, 3 or 4-phase operation (up to 1 MHz per phase) supports up to four complementary buck-switching stages. The unit includes short-circuit protection and adjustable current limiting. Get more information on Analog Devices ADP3192 synchronous buck controller.

DC-TO-DC CONVERTERS WITH DIGITAL CONTROL

To achieve 95-percent efficient dc-to-dc conversion in portable products, Texas Instruments TPS62400 synchronous, dual-channel switcher operates at 2.25-MHz. With its integrated FET, the unit supports up to 400 mA of output current on the first output and up to 600 mA on the second output over an input voltage range of 2.5 to 6 V. A one-pin serial interface, dubbed EasyScale allows dynamic output voltage adjustment during operation. The single-pin interface allows simple digital voltage scaling when powering TI’s TMS320C5000 digital signal processors and OMAP processors used in portable equipment. The unit’s quiescent current is typically 32 µA and operation includes a power save mode, which is implemented at light load currents. Output voltage accuracy in PWM Mode is 1 percent. The 2.25-MHz fixed frequency allows the use of small inductors and capacitors. Get more information on Texas Instruments TPS62400 dual-channel switcher.

HALF-BRIDGE DC-TO-DC CONTROLLER

Designed for 25 to 300-W telecom and computer power supplies, Vishay Intertechnology, Inc.’s 500-kHz half-bridge dc-to-dc controller and synchronous rectifier driver work together to provide over 90 percent dc-to-dc conversion efficiency. The Si9122A controller operates within the telecom voltage range of 36 to 75V and can withstand 100V, 100-ms transients. Capable of controlling and driving both the low and high-side switching devices of a half-bridge circuit, the Si9122A also controls the synchronous rectifier MOSFETs on the secondary side of the bridge.

Instead of using Schottky diode rectifiers, the unit uses a pulse transformer to drive low-on-resistance secondary MOSFETs, enabling increased conversion efficiency. The controller targets power supply modules and network cards for fixed telecom systems, central office switching equipment, distributed power systems, intermediate bus converters and brick converters. For more information on the Vishay Intertechnology Si9122A half-bridge dc-to-dc Controller.