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100% Duty Cycle, Low-Noise, Step-Down, PWM DC-DC Converter

Internal Power MOSFET and Current-Sense Reduces Component Count and Saves Space

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 3.5
VIN (V) (max) 11
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 10
IOUT1 (A) (max) 0.6
Switch Type Internal
Output Adjust. Method Resistor
# DC-DC Outputs 1
Switching Frequency (kHz) 440
Package/Pins SOIC (N)/8
Budgetary
Price (See Notes)
3.04
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 3.5
VIN (V) (max) 11
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 10
IOUT1 (A) (max) 0.6
Switch Type Internal
Output Adjust. Method Resistor
# DC-DC Outputs 1
Switching Frequency (kHz) 440
Package/Pins SOIC (N)/8
Budgetary
Price (See Notes)
3.04

Key Features

  • 95% Efficiency
  • 600mA Output Current
  • Cycle-by-Cycle Current Limiting
  • Low-Dropout, 100% Duty-Cycle Operation, 300mV at 500mA
  • Internal 0.6Ω (typ) MOSFET
  • Internal Synchronous Rectifier
  • High-Frequency Current-Mode PWM
  • External SYNC or Internal 300kHz Oscillator
  • Guaranteed 260kHz to 340kHz Internal Oscillator Frequency Limits
  • 2.5µA Shutdown Mode

Applications/Uses

  • Cell Phones
  • Computer Peripherals
  • Distributed Power Systems
  • Personal Communicators
  • Portable Instrumentation

Description

The MAX887 high-efficiency, step-down DC-DC converter provides an adjustable output from 1.25V to 10.5V. It accepts inputs from 3.5V to 11V and delivers 600mA. Operation to 100% duty cycle minimizes dropout voltage (300mV typ at 500mA). Synchronous rectification reduces output rectifier losses, resulting in efficiency as high as 95%.

Fixed-frequency pulse-width modulation (PWM) reduces noise in sensitive communications applications. Using a high-frequency internal oscillator allows tiny surface-mount components to reduce PC board area, and eliminates audio-frequency interference. A SYNC input allows synchronization to an external clock to avoid interference with sensitive RF and data-acquisition circuits.

The MAX887 features current-mode operation for superior load/line-transient response. Cycle-by-cycle current limiting protects the internal MOSFET and rectifier. A low-current (2.5µA typ) shutdown mode conserves battery life.

Simplified Block Diagram

MAX887, MAX887H: Typical Operating Circuit MAX887, MAX887H: 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 .