IC vendor promotes standard

solution for powering processors

Two manufacturers of switching-regulator ICs have agreed to offer compatible
design solutions for powering the latest generation of microprocessors
from Intel, AMD, and Cyrix. Under this pact, Alpha Semiconductor (Pleasanton,
CA) becomes a true alternative source for the LX1662 series of PWM controllers
recently announced by Linfinity Microelectronics (Garden Grove, CA).

Motherboard designers who select Linfinity Microelectronics' LX1662
series of switching regulators will be able to second-source their designs
with equivalent components from Alpha Semiconductor.

At present, several companies offer switching regulators designed specifically
for the latest Pentium processors, but these parts are generally incompatible
with each other. As a result, in addition to cost and performance requirements,
the designer must consider the risk associated with selecting a unique
design solution.

Linfinity views the agreement with Alpha as the beginning of an industry
standard. The company expects other vendors to follow suit with functionally
equivalent, pin-compatible controllers.

The LX1662/63/64/65 are PWM controllers with on-chip 5-bit D/A converters
used to decode Intel's 4- or 5-bit voltage-identification code. The devices
convert a 5- or 12-V supply voltage to the 1.30 to 3.5-V value required
by the processor while driving external MOSFETs to deliver 15 A or more.

The controllers operate synchro-nously or asynchronously, and typically
produce 85% to 90% efficiencies for a 10-A load. A 200-ns loop response
limits the amount of external capacitance required. Other features include
pulse-by-pulse current limiting, short-circuit protection, and soft-start
capability.

Options include power-good and overvoltage-protection functions, as
well as a linear regulator driver for operating external low-power circuitry.
The most basic version, the LX1662 comes in a 14-pin SOP, which the company
claims is the industry's smallest package for an integrated PWM controller
and 5-bit D/A converter.

The other devices are provided in 16- and 18-pin SOPs. All parts are
currently available with prices starting at $2.04 in quantities of 1,000.
For more information, call Mark Granahan of Linfinity Microelectronics at 714-372-8333.