High-Speed, Digitally Adjusted Step-Down Controllers for Notebook CPUs

Active: In Production.

The MAX1710/MAX1711 step-down controllers are intended for core CPU DC-DC converters in notebook computers. They feature a triple-threat combination of ultra-fast transient response, high DC accuracy, and high efficiency needed for leading-edge CPU core power supplies. Maxim's proprietary Quick-PWM™ quick-response, constant-on-time PWM control scheme handles wide input/output voltage ratios with ease and provides 100ns "instant-on" response to load transients while maintaining a relatively constant switching frequency.

High DC precision is ensured by a 2-wire remote-sensing scheme that compensates for voltage drops in both the ground bus and supply rail. An on-board, digital-to-analog converter (DAC) sets the output voltage in compliance with Mobile Pentium II® CPU specifications.

The MAX1710 achieves high efficiency at a reduced cost by eliminating the current-sense resistor found in traditional current-mode PWMs. Efficiency is further enhanced by an ability to drive very large synchronous-rectifier MOSFETs.

Single-stage buck conversion allows these devices to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, 2-stage conversion (stepping down the +5V system supply instead of the battery) at a higher switching frequency allows the minimum possible physical size.

The MAX1710/MAX1711 are identical except that the MAX1711 have 5-bit DACs and the MAX1710 has a 4-bit DAC. Also, the MAX1711 has a fixed overvoltage protection threshold at V_OUT = 2.25V and undervoltage protection at V_OUT = 0.8V whereas the MAX1710 has variable thresholds that track V_OUT. The MAX1711 is intended for applications where the DAC code may change dynamically.

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