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5V/3.3V or Adjustable, High-Efficiency, Low-Dropout, Step-Down DC-DC Controller

High-Efficiency Step-Down Controller Operates with 4 to 8 Cells

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 3
VIN (V) (max) 16
VOUT1 (V) (min) 1.5
VOUT1 (V) (max) 3.3
IOUT1 (A) (max) 2.5
Switch Type External
Preset VOUT (V) 5
Output Adjust. Method Preset
Resistor
# DC-DC Outputs 1
Switching Frequency (kHz) 300
Package/Pins SOIC (N)/8
Budgetary
Price (See Notes)
2.37
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 3
VIN (V) (max) 16
VOUT1 (V) (min) 1.5
VOUT1 (V) (max) 3.3
IOUT1 (A) (max) 2.5
Switch Type External
Preset VOUT (V) 5
Output Adjust. Method Preset
Resistor
# DC-DC Outputs 1
Switching Frequency (kHz) 300
Package/Pins SOIC (N)/8
Budgetary
Price (See Notes)
2.37

Key Features

  • More than 90% Efficiency (10mA to 1.5A Loads)
  • More than 12.5W Output Power
  • Less than 0.3V Dropout Voltage at 500mA
  • 100µA Max Quiescent Supply Current
  • 5µA Max Shutdown Supply Current
  • 16V Max Input Voltage
  • 5V (MAX1649), 3.3V (MAX1651), or Adjustable Output Voltage
  • Current-Limited Control Scheme
  • Up to 300kHz Switching Frequency
  • Up to 96.5% Duty Cycle

Applications/Uses

  • 5V to 3.3V Green PC Applications
  • Battery-Powered Applications
  • High-Efficiency Step-Down Regulation
  • PDAs

Description

The MAX1649/MAX1651 BiCMOS, step-down, DC-DC switching controllers provide high efficiency over loads ranging from 1mA to more than 2.5A. A unique, current-limited pulse-frequency-modulated (PFM) control scheme gives these devices the benefits of pulse-width-modulation (PWM) converters (high efficiency at heavy loads), while using only 100µA of supply current (vs. 2mA to 10mA for PWM converters). Dropout performance down to 300mV is provided by a high switch duty cycle (96.5%) and a low current-sense threshold (110mV).

A high switching frequency (up to 300kHz) allows these devices to use miniature external components.

The MAX1649/MAX1651 have dropout voltages less than 0.3V at 500mA and accept input voltages up to 16V. Output voltages are preset at 5V (MAX1649), or 3.3V (MAX1651). They can also be adjusted to any voltage from 1.5V to the input voltage by using two resistors.

These step-down controllers drive external P-channel MOSFETs at loads greater than 12.5W. If less power is required, use the MAX639/MAX640/MAX653 step-down converters with on-chip FETs, which allow up to a 225mA load current.

Simplified Block Diagram

MAX1649, MAX1651: Typical Operating Circuit MAX1649, MAX1651: 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 .