General Description

The MAX1964/MAX1965 power-supply controllers are designed to address cost-sensitive applications demanding voltage sequencing/tracking, such as cable modem consumer premise equipment (CPE), xDSL CPE, and set-top boxes. Operating off a low-cost, unregulated DC supply (such as a wall adapter output), the MAX1964 generates three positive outputs and the MAX1965 generates four positive outputs and one negative output to provide an inexpensive system power supply.

Features

♦ 4.5V to 28V Input Voltage Range

♦ Master DC-DC Step-Down Converter:

   Preset 3.3V or Adjustable (1.236V to 0.75 x VIN)

   Output Voltage

   Fixed Frequency (200kHz) PWM Controller

   No Current-Sense Resistor

   Adjustable Current Limit

   95 Efficient

   Soft-Start

♦ Two (MAX1964)/Four (MAX1965) Analog Gain

   Blocks:

   Positive Analog Blocks Drive Low-Cost PNP

   Pass Transistors to Build Positive Linear

   Regulators

   Negative Analog Block (MAX1965) Drives a

   Low-Cost NPN Pass Transistor to Build a

   Negative Linear Regulator

♦ Power-Good Indicator

♦ Voltage Sequencing (MAX1964) or Tracking

   (MAX1965)

Applications

   xDSL, Cable, and ISDN Modems

   Set-Top Boxes

   Wireless Local Loop