3A, 1MHz, 1% Accurate, Internal Switch Step-Down Regulator with Power-OK

The MAX8505 step-down regulator operates from a 2.6V to 5.5V input and generates an adjustable output voltage from 0.8V to 0.85 x VIN at up to 3A. With a 2.6V to 5.5V bias supply, the input voltage can be as low as 2.25V.

The MAX8505 integrates power MOSFETs and operates at 1MHz/500kHz switching frequency to provide a compact design. Current-mode pulse-width-modulated (PWM) control simplifies compensation with ceramic or polymer output capacitors and provides excellent transient response.

The MAX8505 features 1% accurate output over load, line, and temperature variations. Adjustable soft-start is achieved with an external capacitor. During the soft-start period, the voltage-regulation loop is active. This limits the voltage dip when the active devices, such as microprocessors or ASICs connected to the MAX8505's output, apply a sudden load current step upon passing their undervoltage thresholds.

The MAX8505 features current-limit, short-circuit, and thermal-overload protection and enables a rugged design. Open-drain power-OK (POK) monitors the output voltage.

Applications

* µP/ASIC/DSP/FPGA Core and I/O Supplies

* Chipset Supplies

* Network and Telecom Equipment

* Server, RAID, and Storage Systems

* Saves Space—4.9mm x 6mm Footprint, 1µH Inductor, 47µF Ceramic Output Capacitor

* Input Voltage Range

* 2.6V to 5.5V

* Down to 2.25V with Bias Supply

* 0.8V to 0.85 x VIN, 3A Output

* Ceramic or Polymer Capacitors

* ±1% Output Accuracy over Load, Line, and Temperature

* Fast Transient Response

* Adjustable Soft-Start

* In-Regulation Soft-Start Limits Output-Voltage Dips at Power-On

* POK Monitors Output Voltage