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Integrated DDR Power-Supply Solution for Desktops, Notebooks, and Graphic Cards

Product Details

Key Features

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) 1.5
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) 600
Package/Pins TQFN/28
Budgetary
Price (See Notes)
4.52
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Simplified Block Diagram

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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) 1.5
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) 600
Package/Pins TQFN/28
Budgetary
Price (See Notes)
4.52

Key Features

Buck Controller
  • Quick-PWM with 100ns Load-Step Response
  • Up to 95% Efficiency
  • 2V to 28V Input Voltage Range
  • 1.8V/2.5V Fixed or 0.7V to 5.5V Adjustable Output
  • Up to 600kHz Selectable Switching Frequency
  • Programmable Current Limit with Foldback Capability
  • 1.7ms Digital Soft-Start
  • Independent Shutdown and Standby Controls
  • Overvoltage/Undervoltage-Protection Option
  • Power-Good Window Comparator LDO Section
  • Fully Integrated VTT and VTTR Capability
  • VTT Has ±3A Sourcing/Sinking Capability
  • VTT and VTTR Outputs Track VREFIN/2
  • All-Ceramic Output-Capacitor Designs
  • 1.0V to 2.8V Input Voltage Range
  • Power-Good Window Comparator

Applications/Uses

  • DDR I and DDR II Memory Power Supplies
  • Desktop Computers
  • Game Consoles
  • Graphic Cards
  • Networking
  • Notebooks and Desknotes
  • RAID

Description

The MAX8550A integrates a synchronous-buck PWM controller to generate VDDQ, a sourcing and sinking LDO linear regulator to generate VTT, and a 10mA reference output buffer to generate VTTR. The buck controller drives two external n-channel MOSFETs to generate output voltages down to 0.7V from a 2V to 28V input with output currents up to 15A. The LDO can sink or source up to 1.5A continuous and 3A peak current. Both the LDO output and the 10mA reference buffer output can be made track the REFIN voltage. These features make the MAX8550A ideally suited for DDR memory applications desktops, notebooks, and graphic cards.

The PWM controller in the MAX8550A utilizes Maxim's proprietary Quick-PWM™ architecture with programmable switching frequencies of up to 600kHz. This control scheme handles wide input/output voltage ratios with ease and provides 100ns response to load transients while maintaining high efficiency and a relatively constant switching frequency. The MAX8550A offers fully programmable UVP/OVP and skip-mode options ideal portable applications. Skip mode allows for improved efficiency at lighter loads.

The VTT and VTTR outputs track to within 1% of VREFIN/2. The high bandwidth of this LDO regulator allows excellent transient response without the need for bulk capacitors, thus reducing cost and size.

The buck controller and LDO regulators are provided with independent current limits. Adjustable lossless foldback current limit for the buck regulator is achieved by monitoring the drain-to-source voltage drop of the low-side MOSFET. Additionally, overvoltage and undervoltage protection mechanisms are built in. Once the overcurrent condition is removed, the regulator is allowed to enter soft-start again. This helps minimize power dissipation during a short-circuit condition. The MAX8550A allows flexible sequencing and standby power management using the active-low SHDN and active-low STBY inputs, which support DDRs' operating states.

The MAX8550A is available in a small 5mm x 5mm, 28-pin thin QFN package.

Simplified Block Diagram

MAX8550A: Typical Operating Circuit MAX8550A: 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 .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.