The MAX1716/MAX1854/MAX1855 step-down controllers are intended for core CPU DC-DC converters in notebook computers. They feature a dynamically adjustable output (5-bit DAC), ultra-fast transient response, high DC accuracy, and high efficiency needed for leading-edge CPU core power supplies. Maxim's proprietary Quick-PWM™ quick-response, constant-on-time PWM control scheme handles wide input/output voltage ratios with ease and provides 100ns "instant-on" response to load transients while maintaining a relatively constant switching frequency. The MAX1716/MAX1854/MAX1855 are designed specifically for CPU core applications requiring a voltage-positioned supply. The voltage-positioning input (VPS), combined with a high DC accuracy control loop, is used to implement a power supply that modifies its output set point in response to the load current. This arrangement decreases full-load power dissipation and reduces the required number of output capacitors. The 28V input range of the MAX1716/MAX1854/MAX1855 enables single-stage buck conversion from high-voltage batteries for the maximum possible efficiency. Alternatively, the devices' high-frequency capability combined with two-stage conversion (stepping down the +5V system supply instead of the battery) allows the smallest possible physical size. The output voltage can be dynamically adjusted through the 5-bit digital-to-analog converter (DAC) inputs. The MAX1716/MAX1854/MAX1855 are available in a 24-pin QSOP package. For applications requiring SpeedStep® power control (see the MAX1717). Applications * Computers: Desktop, Workstation, Server * Notebook Computers * Servers * Workstations * High-Efficiency Voltage Positioning * Quick-PWM Architecture * ±1% VOUT Line-Regulation Accuracy * Adjustable Output Range (5-Bit DAC) * MAX1716: 0.925V to 1.6V * MAX1854: 0.925V to 2.0V * MAX1855: 0.600V to 1.75V * 2V to 28V Input Range * 200/300/400/550kHz Switching Frequency * Output Undervoltage Protection * Overvoltage Protection (MAX1716/MAX1855) * Drive Large Synchronous-Rectifier MOSFETs * 1.7ms Digital Soft-Start * 700µA ICC Supply Current * 1µA Shutdown Supply Current * 2V ±1% Reference Output * VGATE Transition-Complete Indicator * Small 24-Pin QSOP Package