High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers

Active: In Production.

The MAX8732A/MAX8733A/MAX8734A dual step-down, switch-mode power-supply (SMPS) controllers generate logic-supply voltages in battery-powered systems. The MAX8732A/MAX8733A/MAX8734A include two pulse-width modulation (PWM) controllers, adjustable from 2V to 5.5V or fixed at 5V and 3.3V. These devices feature two linear regulators providing 5V and 3.3V always-on outputs. Each linear regulator provides up to 100mA output current with automatic linear-regulator bootstrapping to the main SMPS outputs. The MAX8732A/MAX8733A/MAX8734A include on-board power-up sequencing, a power-good (PGOOD) output, digital soft-start, and internal soft-stop output discharge that prevents negative voltages on shutdown. Additionally, the outputs are high impedance when V_CC falls below its UVLO set point while the outputs are enabled.

Maxim's proprietary Quick-PWM™ quick-response, constant on-time PWM control scheme operates without sense resistors and provides 100ns response to load transients while maintaining a relatively constant switching frequency. The unique ultrasonic pulse-skipping mode maintains the switching frequency above 25kHz, which eliminates noise in audio applications. Other features include pulse skipping, which maximizes efficiency in light-load applications, and fixed-frequency PWM mode, which reduces RF interference in sensitive applications.

The MAX8732A features a 200kHz/5V and 300kHz/3.3V SMPS for highest efficiency, while the MAX8733A features a 400kHz/5V and 500kHz/3.3V SMPS for "thin and light" applications. The MAX8734A provides a pin-selectable switching frequency, allowing either 200kHz/300kHz or 400kHz/500kHz operation of the 5V/3.3V SMPSs, respectively. The MAX8732A/MAX8733A/MAX8734A are available in 28-pin QSOP packages and operate over the extended temperature range (-40°C to +85°C).

The MAX8732A/MAX8733A/MAX8734A are pin-for-pin upgrades to the MAX1777/MAX1977/MAX1999. The MAX1999 evaluation kit (EV kit) can be used to evaluate the MAX8732A/MAX8733A/MAX8734A.

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