DUAL HIGH-EFFICIENCY BUCK CONTROLLER WITH ACCURATE CURRENT LIMIT FOR NOTEBOOK COMPUTERS
SUNNYVALE, CA-February 13, 2001-Maxim Integrated Products introduces the MAX1845, a dual PWM controller configured for step-down (buck) topologies that provides high efficiency, excellent transient response, and high DC output accuracy needed for stepping down high-voltage batteries to generate low-voltage chipset and RAM power supplies in notebook computers. The CS_ inputs can be used with low-side sense resistors to provide accurate current limits or can be connected to LX_, using low-side MOSFETs as current sense elements.
The on-demand PWM controllers are a free-running, constant on-time type with input feed-forward. This configuration provides ultra-fast transient response, wide input-output differential range, low supply current, and tight load regulation characteristics. The MAX1845 is simple, is easy to compensate, and doesn't have the noise sensitivity of conventional fixed-frequency current-mode PWMs.
The MAX1845 offers high efficiency at a 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.
This product is intended for generating chipset, DRAM, CPU I/O, or other low-voltage supplies down to 1V. The MAX1845 is offered in a small 28-pin QSOP package. All devices are screened for the extended temperature range (-40°C to +85°C). Prices for the MAX1845EEI start at $3.85 (1000-up, FOB USA). A preassembled MAX1845EVKIT (evaluation kit) is available with recommended external components to reduce design time.
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