描述 Description

The MAX649/MAX651/MAX652 BiCMOS, step-down DC-DC switching controllers provide high efficiency over three decades of load current. A unique, current-limited pulse-frequency-modulated (PFM) control scheme gives these devices the benefits of pulse-width-modulation (PWM) converters (high efficiency at heavy loads), while using only 100μA of supply current (vs. 2mA to 10mA for PWM converters). The result is high efficiency over loads ranging from 10mA to more than 2.5A.
These devices use miniature external components. Their high switching frequency (up to 300kHz) allows for less than 9mm diameter surface-mount inductors.
The MAX649/MAX651/MAX652 have dropout voltages less than 1V and accept input voltages up to 16.5V. Output voltages are preset at 5V (MAX649), 3.3V (MAX651), and 3V (MAX652). These controllers can also be adjusted to any voltage from 1.5V to the input voltage by using two resistors.
These step-down controllers drive external P-channel MOSFETs at loads greater than 10W. If less power is required, use the MAX639/MAX640/MAX653 step-down converters with on-chip FETs, which allow up to a 225mA load current.

特性 Features

·More than 90% Efficiency (10mA to 1.5A Loads)
·More than 12.5W Output Power
·100μA Max Quiescent Supply Current
·5μA Max Shutdown Supply Current
·Less than 1.0V Dropout Voltage
·16.5V Max Input Voltage
·5V (MAX649), 3.3V (MAX651), 3V (MAX652), or Adjustable Output Voltage
·Current-Limited Control Scheme
·Up to 300kHz Switching Frequency

應用 Application

·5V至3.3V綠色PC應用
·電池供電應用
·高效降壓轉(zhuǎn)換器
·元件數(shù)最少的DC-DC轉(zhuǎn)換器

簡介

MAX649屬于集成電路（IC）的專用IC。由制造生產(chǎn)的MAX649專用 IC專用專用集成電路 (IC) 或芯片設計用于執(zhí)行特定功能。這個類別包括可尋址開關、空芯儀表驅(qū)動器、音視頻開關、驗證芯片、自動放電、時鐘發(fā)生器、彩色掃描儀，以及各種應用所用的其他許多集成電路。