HIGH-SPEED STEP-DOWN CONTROLLER FOR NOTEBOOK CPUs HAS DIGITAL CONTROL
SUNNYVALE, CA—July 5, 2000—Maxim Integrated Products introduces the MAX1712 step-down controller. Intended as a DC-DC converter for the core CPU in notebook computers, it offers ultra-fast transient response, high DC accuracy, and the high efficiency needed in leading-edge CPU power supplies. Maxim’s proprietary quick-response constant-on-time control scheme (QUICK-PWM™) handles wide ratios of input/output voltage with ease, maintaining a relatively constant switching frequency while providing a 100ns "instant-on" response to load transients.
DC precision is ensured by a 2-wire remote-sensing scheme that compensates for voltage drops in the supply rail and the ground bus. An internal 5-bit digital-to-analog converter sets the output voltage in accordance with Intel’s VRM 9.0 specifications. The output-adjust range is 1.10V to 1.85V, and the reference-voltage output is 2V ±1%.
The MAX1712 achieves high efficiency at reduced cost by eliminating the current-sense resistor found in traditional current-mode PWMs. Efficiency is further enhanced by its ability to drive very large synchronous-rectifier MOSFETs, made possible by powerful internal gate drivers with anti-shoot-through circuitry.
By stepping down high battery voltages directly, the MAX1712’s single-stage buck conversion provides the highest possible efficiency. As an alternative, minimum physical size can be achieved by using a higher switching frequency and by stepping down the +5V system supply instead of the battery making it a two-stage conversion. The internal switching frequency is pin-programmable up to 550kHz, allowing the use of small low-profile resistors and capacitors. The MAX1712 comes in a small 24-pin QSOP package. Prices start from $3.50 (1000-up, FOB USA).
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