500kHz MULTI-OUTPUT POWER-SUPPLY CONTROLLERS WITH HIGH IMPEDANCE IN SHUTDOWN FOR NOTEBOOK COMPUTERS
SUNNYVALE, CA-June 11, 2004-Maxim® Integrated Products, Inc. (NASDAQ: MXIM) introduces the MAX8741/MAX8742 step-down, switch-mode, power-supply controllers which generate logic-supply voltages for battery-powered systems. These high-performance, dual-/triple-output devices include on-board power-up sequencing, power-good signaling with delay, digital soft-start, secondary winding control, low-dropout circuitry, internal frequency-compensation networks, and automatic bootstrapping.
Up to 97% efficiency is achieved through synchronous rectification and MAXIM's proprietary Idle-Mode™ control scheme. Efficiency is greater than 80% over a 1000:1 load-current range, which extends battery life in system suspend or standby mode. Excellent dynamic response corrects output load transients within five clock cycles. Strong 1A on-board gate drivers ensure fast external n-channel MOSFET switching.
These devices feature a logic-controlled and synchronizable fixed-frequency, pulse-width modulation (PWM) operating mode. This reduces noise and RF interference in sensitive mobile-communications and pen-entry applications. For lowest noise under all load conditions, asserting the SKIP/ pin enables the fixed-frequency mode.
The MAX8741/MAX8742 include two PWM regulators, adjustable (2.5V to 5.5V) and fixed (5.0V and 3.3V) modes, and secondary feedback regulation. The MAX8742 contains a 12V, 120mA linear regulator. The MAX8741 includes a secondary feedback input (SECFB) plus a control pin (STEER) that selects which PWM (3.3V or 5V) receives the secondary feedback signal. SECFB provides a method for adjusting the secondary-winding voltage-regulation point with an external resistor divider, and is intended to aid in creating auxiliary voltages other than the fixed 12V.
The MAX8741/MAX8742 contain internal under- and overvoltage protection circuitry and have pin-selectable switching frequencies of 500kHz and 333kHz. They are available in 28-pin SSOP and 32-pin thin QFN 5mm x 5mm packages. The MAX8741/MAX8742 are screened for the extended temperature range (-40°C to +85°C). Prices start at $5.55 (1000-up, FOB USA).
MAXIM is a registered trademark of Maxim Integrated Products, Inc.
Idle Mode is a trademark of Maxim Integrated Products, Inc.
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