MAX1762 AND MAX1791 COMPACT HIGH-EFFICIENCY BUCK CONTROLLERS FOR NOTEBOOKS
SUNNYVALE, CA-December 19, 2000-Maxim Integrated Products introduces the MAX1762 and MAX1791 PWM step-down controllers. These regulators provide high efficiency, excellent transient response, and high DC output accuracy in an extremely compact circuit topology. These features are essential for stepping down high-voltage batteries to generate low-voltage CPU core, I/O, and chipset RAM supplies in space-critical applications such as notebook computers and smart phones.
The MAX1762 and MAX1791 employ Maxim’s proprietary “QuickPWM” quick response, constant-on-time PWM control scheme, which handles wide input/ouput voltage ratios with ease and provides “instant-on-response” response to load transients while maintaining a relatively constant switching frequency. The regulator architecture has two complementary MOSFET output stages, which reduce component count by eliminating external bootstrap capacitors and diodes. The MAX1762 and MAX1791 sense the output current by measuring the voltage across the low-side MOSFET, achieving high efficiency with reduced cost. This technique eliminates the current-sense resistor found in traditional current-mode PWMs. Efficiency is further enhanced by the regulator’s ability to drive large synchronous-rectifier MOSFETs. The MAX1762’s two preset output voltages are 1.8V or 2.5V, while the MAX1791’s output voltages are +3.3V or +5.5V. Both circuits can be adjusted between 0.5V and 5.5V with external resistive voltage dividers.
The MAX1762 and MAX1791 are available in a 10-pin µMAX package. All devices are screened for the extended temperature range (-40°C to +85°C). Prices for the MAX1762 and MAX1791 start at $2.30 (1000-up FOB USA). Preassembled MAX1762 and MAX1791 evaluation kits are available with recommended external components to reduce design time.
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