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Low-Dropout, Wide-Input-Voltage, Step-Down Controllers

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 4.5
VIN (V) (max) 28
VOUT1 (V) (min) 0.6
VOUT1 (V) (max) 28
IOUT1 (A) (max) 20
Switch Type External
Output Adjust. Method Resistor
Synchronous Switching? Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 1400
Package/Pins TQFN/20
Budgetary
Price (See Notes)
2.57
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 4.5
VIN (V) (max) 28
VOUT1 (V) (min) 0.6
VOUT1 (V) (max) 28
IOUT1 (A) (max) 20
Switch Type External
Output Adjust. Method Resistor
Synchronous Switching? Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 1400
Package/Pins TQFN/20
Budgetary
Price (See Notes)
2.57

Key Features

  • Low Dropout with > 99.5% Duty Cycle
  • Lossless High-Side Current Limit
  • Wide 4.5V to 28V Input Range
  • Dynamic Output Voltage Adjustment with Adjustable Offset (MAX8597)
  • Remote Voltage Sensing for Both Positive and Negative Rails (MAX8597)
  • Tracking Output Through REFIN (MAX8597)
  • Adjustable Switching Frequency from 200kHz to 1.4MHz
  • Adjustable Soft-Start
  • Prebias Startup
  • Enable and Power-OK (MAX8598/MAX8599) for Flexible Sequencing
  • 25MHz Error Amplifier
  • Adjustable Hiccup Current Limit for Output Short-Circuit Protection
  • Output Overvoltage Protection (MAX8599)
  • Small, Low-Profile Thin QFN Package

Applications/Uses

  • Chipset Power Supplies
  • Nonisolated Power Modules
  • Tracking Power Supplies (MAX8597)
  • Variable-Speed DC Fan Power Supplies (MAX8597)

Description

The MAX8597/MAX8598/MAX8599 voltage-mode PWM step-down controllers are designed to operate from a 4.5V to 28V input supply and generate output voltages down to 0.6V. A proprietary switching algorithm stretches the duty cycle to > 99.5% for low-dropout design. Unlike conventional step-down regulators using a p-channel high-side MOSFET to achieve high duty cycle, the MAX8597/MAX8598/MAX8599 drive n-channel MOSFETs resulting in high efficiency and high-current-capability designs.

The MAX8597 is available in a 20-pin thin QFN package and is designed for applications that use an analog signal to control the output voltage with an adjustable offset, such as DC fan-speed control. This is achieved with an internal uncommitted operational amplifier. The MAX8597 is also targeted for tracking output-voltage applications for chipsets, ASIC and DSP cores, and I/O supplies. The MAX8598/MAX8599 are available in a 16-pin thin QFN package and do not have the uncommitted operational amplifier, reference input, and reference output, but offer an open-drain, power-OK output.

The MAX8597/MAX8598/MAX8599 allow startup with prebias voltage on the output for applications where a backup supply or a tracking device may charge the output capacitor before the MAX8597/MAX8598/MAX8599 are enabled. In addition, the MAX8599 features output overvoltage protection.

These controllers also feature lossless high-side peak inductor current sensing, adjustable current limit, and hiccup-mode short-circuit protection. Switching frequency is set with an external resistor from 200kHz to 1.4MHz. This wide frequency range combined with a wide-bandwidth error amplifier enables the loop compensation scheme to give the user ample flexibility to optimize for cost, size, and efficiency.

Simplified Block Diagram

MAX8597, MAX8598, MAX8599: Block Diagram MAX8597, MAX8598, MAX8599: Block Diagram 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 .