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Dynamically Adjustable, Synchronous Step-Down Controller for Notebook CPUs

Industry's First Single-Chip Solution to Power Intel SpeedStep CPUs

Product Details

The MAX1717 step-down controller is intended for core CPU DC-DC converters in notebook computers. It features a dynamically adjustable output, 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 output voltage can be dynamically adjusted through the 5-bit digital-to-analog converter (DAC) inputs over a 0.925V to 2V range. A unique feature of the MAX1717 is an internal multiplexer (mux) that accepts two 5-bit DAC settings with only five digital input pins. Output voltage transitions are accomplished with a proprietary precision slew-rate control that minimizes surge currents to and from the battery while guaranteeing "just-in-time" arrival at the new DAC setting.

High DC precision is enhanced by a two-wire remote-sensing scheme that compensates for voltage drops in the ground bus and output voltage rail. Alternatively, the remote-sensing inputs can be used together with the MAX1717's high DC accuracy to implement a voltage-positioned circuit that modifies the load-transient response to reduce output capacitor requirements and full-load power dissipation.

Single-stage buck conversion allows these devices to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, two-stage conversion (stepping down the +5V system supply instead of the battery) at a higher switching frequency allows the minimum possible physical size.

The MAX1717 is available in a 24-pin QSOP package.

Key Features

  • Quick-PWM Architecture
  • ±1% VOUT Accuracy Over Line and Load
  • 5-Bit On-Board DAC with Input Mux
  • Precision-Adjustable VOUT Slew Control
  • 0.925V to 2V Output Adjust Range
  • Supports Voltage-Positioned Applications
  • 2V to 28V Battery Input Range
  • Requires a Separate +5V Bias Supply
  • 200/300/550/1000kHz Switching Frequency
  • Over/Undervoltage Protection
  • Drives Large Synchronous-Rectifier FETs
  • 700µA (typ) ICC Supply Current
  • 2µA (typ) Shutdown Supply Current
  • 2V ±1% Reference Output
  • VGATE Transition-Complete Indicator
  • Small 24-Pin QSOP Package

Applications/Uses

  • 2-Cell to 4-Cell Li+ Battery to CPU Core Supply Converters
  • 5V to CPU Core Supply Converters
  • Notebook Computers with Intel SpeedStep® or Other Dynamically Adjustable Processors

Simplified Block Diagram

MAX1717: Minimal Operating Circuit MAX1717: Minimal Operating Circuit Zoom icon

Technical Docs

Design & Development

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Additional Resources
Maxim Products for Intel IMVP

Description

The MAX1717 evaluation kit (EV kit) demonstrates a high-power, dynamically adjustable notebook CPU application circuit. The MAX1717 DC-DC converter steps down high-voltage batteries and/or AC adapters, generating a precision, low-voltage CPU core VCC rail. The MAX1717 EV kit meets the Intel mobile Pentium® III CPU's transient voltage specification by using voltage positioning to minimize output capacitor requirements.

This fully assembled and tested circuit board provides a digitally adjustable 0.925V to 2V output voltage from a 7V to 24V battery input range. It delivers up to 12A output current with 14.1A peak current. The EV kit operates at 300kHz switching frequency and has superior line- and load-transient response. Output slew-rate control minimizes battery and inductor surge currents. With its precision timer circuit, the MAX1717's output voltage slew rate can be tailored to a given application, providing “just-in-time” arrival at the new DAC setting.

View Details

Features

  • High Speed, Accuracy, and Efficiency
  • Voltage-Positioned Output
  • Lowest Output Capacitor Count (4)
  • Reduces CPU Power Consumption
  • Fast-Response Quick-PWM™ Architecture
  • 7V to 24V Input Voltage Range
  • 0.925V to 2V Output Voltage Range
  • 12A Load-Current Capability (14.1A peak)
  • Controlled Input Surge Current During Output Transition
  • 300kHz Switching Frequency
  • No Current-Sense Resistor
  • VGATE Power-Good/Transition-Complete Indicator
  • 24-Pin QSOP Package
  • Low-Profile Components
  • Fully Assembled and Tested

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Parameters

Key Features

  • Quick-PWM Architecture
  • ±1% VOUT Accuracy Over Line and Load
  • 5-Bit On-Board DAC with Input Mux
  • Precision-Adjustable VOUT Slew Control
  • 0.925V to 2V Output Adjust Range
  • Supports Voltage-Positioned Applications
  • 2V to 28V Battery Input Range
  • Requires a Separate +5V Bias Supply
  • 200/300/550/1000kHz Switching Frequency
  • Over/Undervoltage Protection
  • Drives Large Synchronous-Rectifier FETs
  • 700µA (typ) ICC Supply Current
  • 2µA (typ) Shutdown Supply Current
  • 2V ±1% Reference Output
  • VGATE Transition-Complete Indicator
  • Small 24-Pin QSOP Package

Applications/Uses

  • 2-Cell to 4-Cell Li+ Battery to CPU Core Supply Converters
  • 5V to CPU Core Supply Converters
  • Notebook Computers with Intel SpeedStep® or Other Dynamically Adjustable Processors

Description

The MAX1717 step-down controller is intended for core CPU DC-DC converters in notebook computers. It features a dynamically adjustable output, 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 output voltage can be dynamically adjusted through the 5-bit digital-to-analog converter (DAC) inputs over a 0.925V to 2V range. A unique feature of the MAX1717 is an internal multiplexer (mux) that accepts two 5-bit DAC settings with only five digital input pins. Output voltage transitions are accomplished with a proprietary precision slew-rate control that minimizes surge currents to and from the battery while guaranteeing "just-in-time" arrival at the new DAC setting.

High DC precision is enhanced by a two-wire remote-sensing scheme that compensates for voltage drops in the ground bus and output voltage rail. Alternatively, the remote-sensing inputs can be used together with the MAX1717's high DC accuracy to implement a voltage-positioned circuit that modifies the load-transient response to reduce output capacitor requirements and full-load power dissipation.

Single-stage buck conversion allows these devices to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, two-stage conversion (stepping down the +5V system supply instead of the battery) at a higher switching frequency allows the minimum possible physical size.

The MAX1717 is available in a 24-pin QSOP package.

Simplified Block Diagram

MAX1717: Minimal Operating Circuit MAX1717: Minimal Operating Circuit Zoom icon

Technical Docs

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