Low-Noise, 5.5V Input, PWM Step-Down Regulator

The MAX1692 is a low-noise, pulse-width-modulated (PWM), DC-DC step-down converter. It powers logic and transmitters in small wireless systems such as cellular phones, communicating PDAs, and handy-terminals. The device features an internal synchronous rectifier for high efficiency; it requires no external Schottky diode. Excellent noise characteristics and fixed-frequency operation provide easy post-filtering. The MAX1692 is ideally suited for Li-Ion battery applications. It is also useful for +3V or +5V fixed input applications.

The device operates in one of four modes. Forced PWM mode operates at a fixed frequency regardless of the load. Synchronizable PWM mode allows an external switching frequency to control and minimize harmonics. Idle Mode™ (PWM/PFM) extends battery life by switching to a PFM pulse-skipping mode during light loads. Shutdown mode places the device in standby, reducing quiescent supply current to under 0.1µA.

The MAX1692 can deliver over 600mA. The output voltage can be adjusted from 1.25V to VIN with the input range of +2.7V to +5.5V. Other features of the MAX1692 include high efficiency, low dropout voltage, and a 1.2%-accurate 1.25V reference. It is available in a space-saving 10-pin µMAX package with a height of only 1.11mm.

Applications

* Battery-Operated Devices (1 Li+ or 3 NiMH/NiCd) * Cell Phones * Cordless Phones * CPU I/O Supplies * Notebook Chipset Supplies * PDAs and Handy-Terminals

* +2.7V to +5.5V Input Range

* Adjustable Output from 1.25V to VIN

* 600mA Guaranteed Output Current

* 95% Efficiency

* No Schottky Diode Required

* 85µA Quiescent Current

* 100% Duty Cycle in Dropout

* 750kHz Fixed-Frequency PWM Operation

* Synchronizable Switching Frequency

* Accurate Reference: 1.25V (±1.2%)

* Small 10-Pin µMAX Package