MAXIM Integrated Products, represented by Arrow Electronics , has introduced the MAX1992/MAX1993 high-efficiency pulse-width modulation (PWM) controllers with excellent transient response and high dc output accuracy.
These devices step down high-voltage batteries to generate low-voltage CPU core or chipset/RAM supplies in notebook computers.
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.
Efficiency is enhanced by the ability to drive very large synchronous-rectifier MOSFETs. Using an external current-sense resistor in series with the output or the synchronous rectifier ensures reliable overload and inductor saturation protection.
Alternatively, the controller can sense the current across the synchronous rectifier alone or use lossless inductor sensing for lowest power dissipation.
Single-stage buck conversion allows the MAX1992/MAX1993 to directly step down high-voltage batteries for the highest possible efficiency.
Alternatively, two-stage conversion (stepping down from another system supply rail instead of the battery) at the maximum switching frequency reduces physical size to the minimum possible.
The MAX1992 powers the CPU core, chipset, DRAM, or other supply rails as low as 0.7V. The MAX1993 powers chipsets and graphics processor cores, which require dynamically adjustable output voltages.
The MAX1993 can also be used for active termination buses, which require a tracking input reference.
The MAX1992/MAX1993 are available in a 24-pin thin QFN package with optional overvoltage and undervoltage protection. For dual step-down PWM controllers with inductor saturation protection, external reference input voltage, and dynamically selectable output voltages, refer to the MAX1540/MAX1541 data sheet.
A preassembled MAX1993 evaluation kit is available with recommended external components to reduce design time.