General Description

The MAX687/MAX688/MAX689 low-dropout linear regulators operate with an input-to-output voltage differential limited only by an external PNP transistor. Outputs are fixed at 3.3V (MAX687/MAX688) or 3.0V (MAX689). The only external components required are a PNP pass transistor and output, compensation, and bypass capacitors. Base drive to the external transistor is at least 10mA, permitting output currents to exceed 1A when using high-gain transistors (β > 100). Output current limiting is implemented by limiting the external transistor’s base current. Output voltage monitoring and shutdown functions are included.

特性 Features

? Fixed Outputs:

?? 3.3V (MAX687/MAX688)

?? 3.0V (MAX689)

? Directly Drives External PNP Transistor

? 10mA Min Base-Current Drive for >1A Output

? Low Dropout Voltage:

?? 100mV Dropout at 650mA Output (FZT749)

?? 40mV Dropout at 200mA Output (FZT749)

?? 0.8V Dropout at 4A Output

? Power-Fail Output Monitors the Output Voltage

? Automatic, Latched Shutdown when Output Falls Out

?? of Regulation (MAX687)

? Precision Threshold Shutdown Control

?? (MAX688/MAX689)

? Low Supply Current:

?? 150μA Operating

?? <1μA Shutdown

? 2.7V to 11.0V Supply Range

? 8-Pin DIP/SO/μMAX Packages

? <2mV Line Transient with 3.4V to 3.6V Input

? Output Accuracy

Applications

?? High-Efficiency Linear Regulator

?? Battery-Powered Devices

?? Portable Instruments

?? Portable Telephones

?? Power Supply or Backup Supply for Memory