MAX798

Obsolete

High-Accuracy Step-Down Controller with Synchronous Rectifier for CPU Power

High-Efficiency Over Wide Load Range

Data Sheet (Rev. 0) Product Selection Table

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Overview

96% Efficiency
4.5V to 30V Input Range
1.6V to 6V Adjustable Precision Output
±0.4% Max Total Load-Regulation Error
0.06%/V Max Line-Regulation Error
5V Linear-Regulator Output
Precision 2.505V Reference Output
Automatic Bootstrap Circuit
150kHz/300kHz Fixed-Frequency PWM Operation
Programmable Soft-Start
1.2mA Typical Quiescent Current (V_IN = 12V, V_OUT = 2.5V)
1µA Typical Shutdown Current

The MAX798 high-performance, step-down DC-DC converter provides main CPU power in battery-powered systems. This buck controller achieves 96% efficiency by using synchronous rectification and Maxim's proprietary Idle Mode™ control scheme to extend battery life at full-load (up to 10A) and no-load outputs. The MAX798's high accuracy meets the demanding requirements of the latest-generation CPUs. Excellent dynamic response corrects output transients caused by the latest dynamic-clock CPUs within five 300kHz clock cycles. Unique bootstrap circuitry drives inexpensive N-channel MOSFETs, reducing system cost and eliminating the crowbar switching currents found in some PMOS/NMOS switch designs.

The MAX798 has a logic-controlled and synchronizable fixed-frequency pulse-width-modulating (PWM) operating mode, which reduces noise and RF interference in sensitive mobile-communications and pen-entry applications. The SKIP override input allows automatic switchover to idle-mode operation (for high-efficiency pulse skipping) at light loads, or forces fixed-frequency mode for lowest noise at all loads.

Applications