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Dual Output Controller Packs Two Switchers In One IC

1 September 1998

Dual Output Controller Packs Two Switchers In One IC; Twin Switching Regulators Cut Current, Heat and Cost in Pentium II Processor Power Supply Designs


    East Greenwich, R.I.--Aug. 31, 1998--The new CS-5132, a dual output CPU Buck controller from Cherry Semiconductor Corporation, is the industry's first dual-channel switching regulator IC having both a synchronous and a nonsynchronous switcher. Intended for high-performance motherboards using Pentium(R) II microprocessors, the CS-5132 replaces the linear regulator of conventional controller chips with a switcher to reduce current flow in designs where increased component counts draw larger currents. The CS-5132 offers very fast transient response time, reduces heat dissipation and component cost. Split plane board layout is simplified through the use of the CS-5132's twin controllers, and by incorporating the power control and monitoring functions of these circuits in a single IC.
    The CS-5132's synchronous output powers the Pentium(R) II core logic (VCC(CORE)), and drives dual external NFETs. The nonsynchronous side drives a single external NFET and can be used to handle I/O logic (VI/O). Both controllers use Cherry Semiconductor's proprietary V2(TM)(2) control logic, the fastest known control method with 200ns transient response and the best DC accuracy available in the industry. V2(TM) topology provides better line and load regulation through two independent voltage loops. A slow feedback loop sets the DC accuracy and a fast feedback loop sets the transient response.
    The CS-5132 incorporates a host of control features, simplifying power supply design. A single pin on the package controls four functions: soft start, output enable, error amplifier compensation, and hiccup-mode current limit timing, which requires just a single external capacitor to implement. Overcurrent protection is provided through an external "Droop" resistor which senses current flow and feeds the resulting voltage drop to a current-sense comparator on the CS-5132. Overvoltage protection for the VCC(CORE) output is inherent to the normal operation of the V2(TM) control logic and requires no additional components. Adaptive Voltage Positioning is a transient-response technique that pre-positions the voltage across the output capacitors to reduce the total output voltage excursions during load changes. Power Good is an open-collector TTL signal level that monitors the VCC(CORE) switcher output and is pulled low when the regulator output exceeds +/- 8.5% (typical) of the nominal output voltage.
    The CS-5132's synchronous controller has a 5-bit digital-to-analog converter (DAC) that is programmed externally to set the supply voltage of the Pentium(R) II core. The output voltage can be programmed in two ranges, 2.125V to 3.525V in 100mV steps, and 1.325V to 2.075V in 50mV steps, depending on the digital input code. If all five bits are left open, any voltage can be chosen by using an external resistor divider which is fed back to a feedback input on the CS-5132.
    The CS-5132's operating voltage range is 8.5V to 14V. It is supplied in a 24-lead small-outline (SO) wide-body, surface-mount plastic package rated for operation over the temperature range of 0(degree)C to 125(degree)C junction temperature.
    In quantities of 10,000 pieces, the CS-5132 is priced at $2.01 each. Data Sheets and samples can be requested via the Cherry Semiconductor website at http://www.cherry-semi.com. Reference designs, demonstration kits and samples are available to qualified individuals through Cherry's local sales and applications personnel.
    Cherry Semiconductor Corporation designs and manufactures standard, semi-custom and custom integrated circuits for the automotive, communications, computer and power management markets worldwide. As both a QS 9000 and ISO 9000 certified facility, Cherry Semiconductor pursues a corporate quality goal of 2.0 defects per billion on all new product. Cherry Semiconductor Corporation is a wholly owned subsidiary of The Cherry Corporation, Waukegan, Illinois.


    For more information, contact: Cherry Semiconductor Corporation, 2000 South County Trail, East Greenwich, RI 02818 (USA). Phone: 1-800-272-3601. Fax: (401) 885-5786. E-mail: info@cherry-semi.com. Internet: www.cherry-semi.com

(1) Pentium(R) is a registered trademark of Intel Corporation. (2) V2 is a registered trademark of Switch Power Inc.

NOTE TO EDITORS: In any reference in copy to "V2", the 2 is supposed to be superscripted.