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General Description

The MAX730A/MAX738A/MAX744A are 5V-output CMOS, step-down switching regulators. The MAX738A/MAX744A accept inputs from 6V to 16V and deliver 750mA. The MAX744A guarantees 500mA load capability for inputs above 6V and has tighter oscillator frequency limits for low-noise (radio) applications. The MAX730A accepts inputs between 5.2V and 11V and delivers 450mA for inputs above 6V. Typical efficiencies are 85 to 96. Quiescent supply current is 1.7mA and only 6µA in shutdown.

Pulse-width modulation (PWM) current-mode control provides precise output regulation and excellent transient responses. Output voltage accuracy is guaranteed to be ±5 over line, load, and temperature variations. Fixed-frequency switching allows easy filtering of output ripple and noise, as well as the use of small external components. These regulators require only a single inductor value to work in most applications, so no inductor design is necessary.

The MAX730A/MAX738A/MAX744A also feature cycle by-cycle current limiting, overcurrent limiting, undervoltage lockout, and programmable soft-start protection.

Features

♦ 750mA Load Currents (MAX738A/MAX744A)

♦ High-Frequency, Current-Mode PWM

♦ 159kHz to 212.5kHz Guaranteed Oscillator

   Frequency Limits (MAX744A)

♦ 85 to 96 Efficiencies

♦ 1.7mA Quiescent Current

♦ 6µA Shutdown Supply Current

♦ Single Preselected Inductor Value,

   No Component Design Required

♦ Overcurrent, Soft-Start, and Undervoltage

   Lockout Protection

♦ Cycle-by-Cycle Current Limiting

♦ 8-Pin DIP/SO Packages (MAX730A)

Applications

   Portable Instruments

   Cellular Phones and Radios

   Personal Communicators

   Distributed Power Systems

   Computer Peripherals