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500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 4.2
VIN (V) (max) 30
VOUT1 (V) (min) 2.5
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 5
Switch Type External
Preset VOUT (V) 5
Output Adjust. Method Resistor
Synchronous Switching? Yes
Power Good Signal Yes
# DC-DC Outputs 2
Switching Frequency (kHz) 330
Package/Pins SSOP/28
TQFN/32
Budgetary
Price (See Notes)
6.99
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 4.2
VIN (V) (max) 30
VOUT1 (V) (min) 2.5
VOUT1 (V) (max) 5.5
IOUT1 (A) (max) 5
Switch Type External
Preset VOUT (V) 5
Output Adjust. Method Resistor
Synchronous Switching? Yes
Power Good Signal Yes
# DC-DC Outputs 2
Switching Frequency (kHz) 330
Package/Pins SSOP/28
TQFN/32
Budgetary
Price (See Notes)
6.99

Key Features

  • 97% Efficiency
  • 4.2V to 30V Input Range
  • 2.5V to 5.5V Dual Adjustable Outputs
  • Selectable 3.3V and 5V Fixed or Adjustable Outputs (Dual Mode™)
  • 12V Linear Regulator
  • Adjustable Secondary Feedback (MAX1901/MAX1904)
  • 5V/50mA Linear Regulator Output
  • Precision 2.5V Reference Output
  • Programmable Power-Up Sequencing
  • Power-Good (active-low RESET) Output
  • Output Overvoltage Protection (MAX1901/MAX1902)
  • Output Undervoltage Shutdown (MAX1901/MAX1902)
  • 333kHz/500kHz Low-Noise, Fixed-Frequency Operation
  • Low-Dropout, 98% Duty-Factor Operation
  • 2.5mW Typical Quiescent Power (12V input, both SMPSs on)
  • 4µA Typical Shutdown Current
  • Applications/Uses

    • Desktop CPU Local DC-DC Converters
    • Notebook and Subnotebook Computers
    • PDAs and Mobile Communicators

    Description

    The MAX1901/MAX1902/MAX1904 are buck-topology, step-down, switch-mode, power-supply controllers that generate logic-supply voltages in battery-powered systems. These high-performance, dual/triple-output devices include on-board power-up sequencing, power-good signaling with delay, digital soft-start, secondary winding control, low dropout circuitry, internal frequency-compensation networks, and automatic bootstrapping.

    Up to 97% efficiency is achieved through synchronous rectification and Maxim's proprietary Idle Mode™ control scheme. Efficiency is greater than 80% over a 1000:1 load-current range, which extends battery life in system suspend or standby mode. Excellent dynamic response corrects output load transients within five clock cycles. Strong 1A on-board gate drivers ensure fast external N-channel MOSFET switching.

    These devices feature a logic-controlled and synchronizable, fixed-frequency, pulse-width modulation (PWM) operating mode. This reduces noise and RF interference in sensitive mobile communications and pen-entry applications. Asserting the active-low SKIP pin enables fixed-frequency mode, for lowest noise under all load conditions.

    The MAX1901/MAX1902/MAX1904 include two PWM regulators, adjustable from 2.5V to 5.5V with fixed 5.0V and 3.3V modes. All these devices include secondary feedback regulation, and the MAX1902 contains a 12V/120mA linear regulator. The MAX1901/MAX1904 include a secondary feedback input (SECFB), plus a control pin (STEER) that selects which PWM (3.3V or 5V) receives the secondary feedback signal. SECFB provides a method for adjusting the secondary winding voltage regulation point with an external resistor divider, and is intended to aid in creating auxiliary voltages other than fixed 12V.

    The MAX1901/MAX1902 contain internal output overvoltage and undervoltage protection features.

    Simplified Block Diagram

    MAX1901, MAX1902, MAX1904: Functional Diagram MAX1901, MAX1902, MAX1904: Functional Diagram 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 .