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Quick-PWM Step-Down Controllers with Inductor Saturation Protection and Dynamic Output Voltages

Quick-PWM Step-Down Controllers with Inductor Saturation Protection and Dynamic Output Voltages

Product Details

The MAX1992/MAX1993 pulse-width modulation (PWM) controllers provide high-efficiency, excellent transient response, and high DC output accuracy. The devices step down high-voltage batteries to generate low-voltage CPU core or chipset/RAM supplies in notebook computers.

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. Efficiency is enhanced by the ability to drive very large synchronous-rectifier MOSFETs. Current sensing to ensure reliable overload and inductor saturation protection is available using an external current-sense resistor in series with the output. Alternatively, the controller can sense the current across the synchronous rectifier alone or use lossless inductor sensing for lowest power dissipation.

Single-stage buck conversion allows the MAX1992/MAX1993 to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, two-stage conversion (stepping down from another system supply rail instead of the battery) at the maximum switching frequency allows the minimum possible physical size.

The MAX1992 powers the CPU core, chipset, DRAM, or other supply rails as low as 0.7V. The MAX1993 powers chipsets and graphics processor cores, which require dynamically adjustable output voltages. The MAX1993 provides a tracking input that can be used for active termination buses. The MAX1992/MAX1993 are available in a 24-pin thin QFN package with optional overvoltage and undervoltage protection.

For dual step-down PWM controllers with inductor saturation protection, external reference input voltage, and dynamically selectable output voltages, refer to the MAX1540/MAX1541 data sheet.

Key Features

  • Inductor Saturation Protection
  • Accurate Current Limit
  • Ultra-High Efficiency
  • Quick-PWM with 100ns Load-Step Response
  • MAX1992
    • 1.8V/2.5V Fixed or 0.7V to 5.5V Adjustable Output Range
  • MAX1993
    • External Reference Input
    • Dynamically Selectable Output Voltage (0.7V to 5.5V)
    • Optional Power-Good and Fault Blanking During Transitions
  • ±1% VOUT Accuracy Over Line and Load
  • 2V to 28V Battery Input Range (VIN)
  • 200/300/450/600kHz Switching Frequency
  • Overvoltage/Undervoltage Protection Option
  • 1.7ms Digital Soft-Start
  • Drives Large Synchronous Rectifier FETs
  • 2V ±0.7% Reference Output
  • Power-Good Window Comparator

Applications/Uses

  • 1.8V and 2.5V Supplies
  • Active Termination Buses (MAX1993)
  • Core/IO Supplies as Low as 0.7V
  • CPU/Chipset/GPU with Dynamic Voltage Cores
  • DDR Memory Termination (MAX1993)
  • Notebook Computers
Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 2
VIN (V) (max) 28
VOUT1 (V) (min) 0.7
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 4
Switch Type External
Preset VOUT (V) 1.8
2.5
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
Power Good Signal Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 300
Package/Pins TQFN/24
Budgetary
Price (See Notes)
$3.96 @1k
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Simplified Block Diagram

MAX1992, MAX1992ETG, MAX1993: Typical Operating Circuit MAX1992, MAX1992ETG, MAX1993: Typical Operating Circuit Zoom icon

Technical Docs

Design & Development

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Description

The MAX1993 evaluation kit (EV kit) demonstrates the MAX1993's standard 4A application circuit. This DC-to-DC converter steps down high-voltage batteries and/or AC adapters, generating a precision, low-voltage rail for use as chipset, DRAM, and other low-voltage supplies.

The MAX1993 EV kit provides a dynamically adjustable 1.0V/1.5V output voltage from 7V to 24V battery input range. It delivers up to 4A output current with greater than 90% efficiency. The EV kit operates at 300kHz switching frequency and has superior line- and load-transient response.

This EV kit is a fully assembled and tested circuit board. It also allows the evaluation of other dynamically adjustable output voltages in the 0.7V to 5.5V range by changing R6, R7, and R8 resistors.

This EV kit can also be used to evaluate the MAX1992, which has preset 1.8V/2.5V output voltages.

View Details

Features

  • 7V to 24V Input Voltage Range
  • Preset 1.8V/2.5V Output Voltages (Adjustable from 0.7V to 5.5V, MAX1992)
  • Dynamically Selectable Output Voltages 1.0V/1.5V (Adjustable from 0.7V to 5.5V, MAX1993)
  • 4A Output Current
  • 300kHz Switching Frequency
  • Selectable Inductor Saturation Protection
  • Power-Good Output
  • Selectable Overvoltage/Undervoltage Protection
  • Low-Profile Components
  • Fully Assembled and Tested

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 2
VIN (V) (max) 28
VOUT1 (V) (min) 0.7
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 4
Switch Type External
Preset VOUT (V) 1.8
2.5
Output Adjust. Method Preset
Resistor
Synchronous Switching? Yes
Power Good Signal Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 300
Package/Pins TQFN/24
Budgetary
Price (See Notes)
$3.96 @1k

Key Features

  • Inductor Saturation Protection
  • Accurate Current Limit
  • Ultra-High Efficiency
  • Quick-PWM with 100ns Load-Step Response
  • MAX1992
    • 1.8V/2.5V Fixed or 0.7V to 5.5V Adjustable Output Range
  • MAX1993
    • External Reference Input
    • Dynamically Selectable Output Voltage (0.7V to 5.5V)
    • Optional Power-Good and Fault Blanking During Transitions
  • ±1% VOUT Accuracy Over Line and Load
  • 2V to 28V Battery Input Range (VIN)
  • 200/300/450/600kHz Switching Frequency
  • Overvoltage/Undervoltage Protection Option
  • 1.7ms Digital Soft-Start
  • Drives Large Synchronous Rectifier FETs
  • 2V ±0.7% Reference Output
  • Power-Good Window Comparator

Applications/Uses

  • 1.8V and 2.5V Supplies
  • Active Termination Buses (MAX1993)
  • Core/IO Supplies as Low as 0.7V
  • CPU/Chipset/GPU with Dynamic Voltage Cores
  • DDR Memory Termination (MAX1993)
  • Notebook Computers

Description

The MAX1992/MAX1993 pulse-width modulation (PWM) controllers provide high-efficiency, excellent transient response, and high DC output accuracy. The devices step down high-voltage batteries to generate low-voltage CPU core or chipset/RAM supplies in notebook computers.

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. Efficiency is enhanced by the ability to drive very large synchronous-rectifier MOSFETs. Current sensing to ensure reliable overload and inductor saturation protection is available using an external current-sense resistor in series with the output. Alternatively, the controller can sense the current across the synchronous rectifier alone or use lossless inductor sensing for lowest power dissipation.

Single-stage buck conversion allows the MAX1992/MAX1993 to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, two-stage conversion (stepping down from another system supply rail instead of the battery) at the maximum switching frequency allows the minimum possible physical size.

The MAX1992 powers the CPU core, chipset, DRAM, or other supply rails as low as 0.7V. The MAX1993 powers chipsets and graphics processor cores, which require dynamically adjustable output voltages. The MAX1993 provides a tracking input that can be used for active termination buses. The MAX1992/MAX1993 are available in a 24-pin thin QFN package with optional overvoltage and undervoltage protection.

For dual step-down PWM controllers with inductor saturation protection, external reference input voltage, and dynamically selectable output voltages, refer to the MAX1540/MAX1541 data sheet.

Simplified Block Diagram

MAX1992, MAX1992ETG, MAX1993: Typical Operating Circuit MAX1992, MAX1992ETG, MAX1993: Typical 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