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3A, 1MHz, DDR Memory Termination Supply

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 3
VIN (V) (max) 5.5
VOUT1 (V) (min) 1.1
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 3
Switch Type Internal
Output Adjust. Method Resistor
Synchronous Switching? Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 1000
Package/Pins QSOP/16
TQFN/28
Budgetary
Price (See Notes)
5.5
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Simplified Block Diagram

Technical Docs

Data Sheet 3A, 1MHz, DDR Memory Termination Supply Sep 27, 2002

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 3
VIN (V) (max) 5.5
VOUT1 (V) (min) 1.1
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 3
Switch Type Internal
Output Adjust. Method Resistor
Synchronous Switching? Yes
# DC-DC Outputs 1
Switching Frequency (kHz) 1000
Package/Pins QSOP/16
TQFN/28
Budgetary
Price (See Notes)
5.5

Key Features

  • Source/Sink 3A
  • ±1% Output Accuracy
  • Up to 1MHz Switching Frequency
  • 93% Efficiency
  • Internal PMOS/NMOS Switches
    • 90mΩ/70mΩOn-Resistance at VIN = 4.5V
    • 110mΩ/80mΩ On-Resistance at VIN = 3V
  • 1.1V to VIN Adjustable Output Voltage
  • 3V to 5.5V Input Voltage Range
  • <1µA Shutdown Supply Current
  • Programmable Constant-Off-Time Operation
  • Thermal Shutdown
  • Adjustable Soft-Start Inrush Current Limiting
  • Output Short-Circuit Protection

Applications/Uses

  • Active Termination Buses (MAX1993)
  • DDR Memory Termination (MAX1993)

Description

The MAX1809 is a reversible energy flow, constant-off-time, pulse-width modulated (PWM), step-down DC-DC converter. It is ideal for use in notebook and subnotebook computers that require 1.1V to 5V active termination power supplies. This device features an internal PMOS power switch and internal synchronous rectifier for high efficiency and reduced component count. The internal 90mΩ PMOS power switch and 70mΩ NMOS synchronous-rectifier switch easily deliver continuous load currents up to 3A. The MAX1809 accurately tracks an external reference voltage, produces an adjustable output from 1.1V to VIN, and achieves efficiencies as high as 93%.

The MAX1809 uses a unique current-mode, constant-off-time, PWM control scheme that allows the output to source or sink current. This feature allows energy to return to the input power supply that otherwise would be wasted. The programmable constant-off-time architecture sets switching frequencies up to 1MHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The MAX1809 features an adjustable soft-start to limit surge currents during startup, a 100% duty-cycle mode for low-dropout operation, and a low-power shutdown mode that disables the power switches and reduces supply current below 1µA. The MAX1809 is available in a 28-pin QFN with an exposed backside pad, a 28-pin thin QFN, or a 16-pin QSOP.

Simplified Block Diagram

MAX1809: Typical Operating Circuit MAX1809: Typical Operating Circuit Zoom icon

Technical Docs

Data Sheet 3A, 1MHz, DDR Memory Termination Supply Sep 27, 2002

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 .