1.6V to 5.5V Input, 0.5% Accurate, Dual 180° Out-of-Phase Step-Down Controllers

The MAX1955/MAX1956 are dual-output, fixed-frequency, voltage-mode, pulse-width modulated (PWM) step-down controllers with 0.5% output accuracy. Each controller switches at a constant 600kHz and is 180° out-of-phase with the other controller, reducing input ripple current and the number of input capacitors.

An on-chip bias supply generates a 5V gate drive to deliver up to 25A output current per phase with low-cost N-channel MOSFETs at up to 93% efficiency. Lossless adjustable current limit eliminates expensive current-sense resistors and improves efficiency. Foldback current limit reduces power dissipation during short-circuit conditions and handles transient overloads better than controllers using hiccup-mode short-circuit protection.

Output voltage margining shifts output voltage by ±4% from the nominal value to simplify system test. Outputs also can be powered up and down in selectable sequences to meet core and logic supply-rail requirements.

The MAX1955/MAX1956 are available in a 28-lead thin QFN package with exposed pad.

Applications

* DSP, ASIC, µP, and FPGA Supplies * Servers * Telecom and Network Equipment * Wireless Base Stations

* Operates from a 1.6V to 5.5V Supply (MAX1956)

* 0.5% Output Accuracy

* 0.8V to 0.9VIN Output Range

* Up to 25A per Phase Output Current

* On-Chip Boost Regulator Provides 5V Gate Drive

* Up to 93% Efficiency

* 180° Out-of-Phase Operation

* ±4% Voltage Margining

* Lossless, Foldback Current Limit

* Selectable Voltage Sequencing

* Synchronizable to External Clock

* Digital Soft-Start and Soft-Stop

* Small 28-Pin, 5mm x 5mm Thin QFN Package