General Description

The MAX1515 constant-off-time, pulse-width-modulated (PWM) source/sink step-down DC-DC converter is optimized for use in low-voltage active-termination power rails or chipset power supplies in notebook and sub-notebook computers. This device features dual internal n-channel MOSFET power switches for high efficiency and reduced component count. External Schottky diodes are not required. An integrated boost switch eliminates the need for an external boost diode. The internal 40mΩ NMOS power switches easily source and sink continuous load currents up to 3A. The MAX1515 produces an adjustable output from +0.5V to +2.7V and achieves efficiencies as high as 95.

Features

♦ Dual 40mΩ Internal n-Channel MOSFETs

♦ Integrated Boost Switch

♦ +1.3V to +3.6V Input Voltage Range

♦ 1 VOUT Accuracy Over Line and Load

♦ 1MHz Maximum Switching Frequency

♦ DDR Termination Regulator (DDR Mode)

   Tracking Output Voltage

   Source/Sink Pulse Skipping

   ±5mA Reference Buffer

♦ Output Voltage (Non-DDR Mode)

   +2.5V, +1.8V, or +1.5V Pin Selectable

   +0.5V to +2.7V Adjustable

♦ 1.1V ±0.75 Reference Output

♦ Adjustable Soft-Start Inrush Current Limiting

♦ < 1µA (typ) Shutdown Supply Current

♦ < 800µA (max) Operating Supply Current

♦ Selectable Pulse-Skipping Operation at Light Loads

♦ Positive and Negative Current Limit

♦ Power-Good Window Comparator

♦ Output Short-Circuit Protection

Applications

   Notebook DDR Memory Termination

   Active-Termination Buses

   Chipset/Graphics Processor Supplies