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Low-Cost, Wide Input Range, Step-Down Controllers with Foldback Current Limit

2.7V to 28V Input, 15A, Step-Down, DC-DC Controllers for Desktop and Graphic Card Supplies have Foldback Current Protection

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 2.7
VIN (V) (max) 28
VOUT1 (V) (min) 0.8
VOUT1 (V) (max) 23
IOUT1 (A) (max) 15
Switch Type External
Output Adjust. Method Resistor
Synchronous Switching? Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 300
Package/Pins UMAX/10
Budgetary
Price (See Notes)
1.5
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 2.7
VIN (V) (max) 28
VOUT1 (V) (min) 0.8
VOUT1 (V) (max) 23
IOUT1 (A) (max) 15
Switch Type External
Output Adjust. Method Resistor
Synchronous Switching? Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 300
Package/Pins UMAX/10
Budgetary
Price (See Notes)
1.5

Key Features

  • 2.7V to 28V Input Range
  • Foldback Short-Circuit Protection
  • No Additional Bias Supply Needed
  • 0.8V to 0.83 x VIN Output
  • Up to 95% Efficiency
  • Low-Cost External Components
  • No Current-Sense Resistor
  • All n-Channel MOSFET Design
  • Adaptive Gate Drivers Eliminate Shoot-Through
  • Lossless Overcurrent and Short-Circuit Protection
  • 300kHz Switching Frequency (MAX8545/MAX8546)
  • 100kHz Switching Frequency (MAX8548)
  • Pin-Compatible with the MAX1967
  • Thermal Shutdown

Applications/Uses

  • Cable Modems and Routers
  • Desktops and Desknotes
  • Graphic Card and Video Supplies
  • Networking Power Supplies
  • Notebook Docking Station Supplies
  • PCI Express® Power Supplies
  • Set-Top Boxes
  • Telecom Power Supplies

Description

The MAX8545/MAX8546/MAX8548 are voltage-mode pulse-width-modulated (PWM), step-down DC-DC controllers ideal for a variety of cost-sensitive applications. They drive low-cost n-channel MOSFETs for both the high-side switch and synchronous rectifier, and require no external current-sense resistor. These devices can supply output voltages as low as 0.8V.

The MAX8545/MAX8546/MAX8548 have a wide 2.7V to 28V input range, and do not need any additional bias voltage. The output voltage can be precisely regulated from 0.8V to 0.83 x VIN. These devices can provide efficiency up to 95%. Lossless short-circuit and current-limit protection is provided by monitoring the RDS(ON) of the low-side MOSFET. The MAX8545 and MAX8548 have a current-limit threshold of 320mV, while the MAX8546 has a current-limit threshold of 165mV. All devices feature foldback-current capability to minimize power dissipation under short-circuit condition. Pulling the COMP/EN pin low with an open-collector or low-capacitance, open-drain device can shut down all devices.

The MAX8545/MAX8546 operate at 300kHz and the MAX8548 operates at 100kHz. The MAX8545/MAX8546/MAX8548 are compatible with low-cost aluminum electrolytic capacitors. Input undervoltage lockout prevents proper operation under power-sag operations to prevent external MOSFETs from overheating. Internal soft-start is included to reduce inrush current. These devices are offered in space-saving 10-pin µMAX® packages.

Simplified Block Diagram

MAX8545, MAX8546, MAX8548: Typical Operating Circuit MAX8545, MAX8546, MAX8548: 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 .