5V, Step-Down, Current-Mode PWM DC-DC Converters

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.

Applications

* Cell Phones * Computer Peripherals * Distributed Power Systems * Personal Communicators * Portable Instrumentation

* 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)