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High-Efficiency, Triple-Output, Keep-Alive Power Supply for Notebook Computers

High-Efficiency, Triple-Output, Keep-Alive Power Supply for Notebook Computers

Product Details

Key Features

Applications/Uses

Simplified Block Diagram

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Key Features

  • One Switching and Two Linear Regulators
  • Switching Regulator
    • +4.5V to +24V Input Voltage Range
    • Over 95% Efficiency
    • Up to 500mA Output Current
    • Up to 200kHz Switching Frequency
    • Fixed 5V or Adjustable Output Voltage
    • Internal 0.5Ω PMOS Switch
    • 100% Maximum Duty Cycle for Low-Dropout Operation
  • Two Low-Dropout Linear Regulators
    • Up to 160mA Output Current (Each)
    • 3.3V/Adj Output Voltage for OUT1
    • 1.8V/Adj Output Voltage for OUT2
  • ±1.5% Accurate Output Voltage
  • ±4% Accurate Shutdown for Low Battery Detection
  • Thermal Shutdown Protection
  • POK Output
  • 1mW Typical Standby Power

Applications/Uses

  • 2 to 4 Li+ Cell Battery-Powered Devices
  • Handheld Devices
  • Keep-Alive Supplies
  • Notebook and Subnotebook Computers
  • Standby Supplies
  • Wake On LAN®

Description

The MAX1534 is a high-efficiency, triple-output power supply for keep-alive (always on) voltage rails. The 500mA buck regulator with an internal current-limited 0.5Ω PMOS steps down the battery or wall adapter supply rail to a fixed 5V or an adjustable output voltage. Two integrated low-voltage linear regulators follow this output and provide two independent preset output voltages of 3.3V and 1.8V, or adjustable output voltages.

The buck regulator utilizes a peak current-limit, pulse-frequency modulation (PFM) architecture for highest light-load efficiency to conserve battery life. High switching frequencies (up to 200kHz) allow the use of tiny surface-mount inductors and output capacitors. Operation to 100% duty cycle minimizes dropout voltage (250mV at 500mA).

The low-dropout linear regulators use an internal P-channel metal-oxide (PMOS) pass transistor to minimize supply current and deliver up to 160mA each of continuous current.

The MAX1534 includes a power-OK (POK) signal that indicates all outputs are in regulation. The 4% accurate threshold of the active-low SHDN input permits its use as a low-battery detector.

The MAX1534 is available in a small 16-pin thin QFN (4mm x 4mm) package, occupying 33% less board space than discrete solutions.

Simplified Block Diagram

MAX1534: Typical Operating Circuit MAX1534: Typical Operating Circuit Zoom icon

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .