The MAX17017 is a quad-output controller for ultramobile portable computers (UMPCs) that rely on a lowpower architecture. The MAX17017 provides a compact, low-cost controller capable of providing four independent regulators—a main stage, a 3AP-P internal stepdown, a 5AP-P internal step-down, and a 2A source/sink linear regulator.

    The main regulator can be configured as either a stepdown converter (for 2 to 4 Li+ cell applications) or as a step-up converter (for 1 Li+ cell applications). The internal switching regulators include 5V synchronous MOSFETs that can be powered directly from a single Li+ cell or from the main 3.3V/5V power stages. Finally, the linear regulator is capable of sourcing and sinking 2A to support DDR termination requirements or to generate a fixed output voltage.

    The step-down converters use a peak current-mode, fixed-frequency control scheme—an easy to implement architecture that does not sacrifice fast-transient response. This architecture also supports peak currentlimit protection and pulse-skipping operation to maintain high efficiency under light-load conditions.

    Separate enable inputs and independent open-drain power-good outputs allow flexible power sequencing. A soft-start function gradually ramps up the output voltage to reduce the inrush current. Disabled regulators enter high-impedance states to avoid negative output voltage created by rapidly discharging the output through the low-side MOSFET. The MAX17017 also includes output undervoltage, output overvoltage, and thermal-fault protection.

    The MAX17017 is available in a 48-pin, 6mm x 6mm thin QFN package.

    MAX17017主要特性:

    _ Fixed-Frequency, Current-Mode Controllers

    _ 5.5V to 28V Input Range (Step-Down) or 3V to 5V Input Range (Step-Up)

    _ 1x Step-Up or Step-Down Controller

    _ 1x Internal 5AP-P Step-Down Regulator

    _ 1x Internal 3AP-P Step-Down Regulator

    _ 1x 2A Source/Sink Linear Regulator with Dynamic REFIN

    _ Internal BST Diodes

    _ Internal 5V, 50mA Linear Regulator

    _ Fault Protection—Undervoltage, Overvoltage, Thermal, Peak Current Limit

    _ Independent Enable Inputs and Power-Good Outputs

    _ Voltage-Controlled Soft-Start

    _ High-Impedance Shutdown

    _ 10μA (typ) Shutdown Current

    MAX17017应用:

    1to-4 Li+ Cell Battery-Powered Devices

    Low-Power Architecture

    Ultra-Mobile PC (UMPC)

    Portable Gaming

    Notebook and Subnotebook Computers

    PDAs and Mobile Communicators

    图1.MAX17017方框图

    图2.PWM比较功能方框图

    图3.MAX17017标准应用电路(1)