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Dual 180° Out-of-Phase PWM Step-Down Controllers with POR

Product Details

The MAX1875/MAX1876 dual, synchronized, step-down controller generates two outputs from input supplies ranging from 4.75V to 23V. Each output is adjustable from sub-1V to 18V and supports loads of 10A or higher. Input voltage ripple and total RMS input ripple current are reduced by synchronized 180° out-of-phase operation.

The switching frequency is adjustable from 100kHz to 600kHz with an external resistor. Alternatively, the controller can be synchronized to an external clock generated to another MAX1875/MAX1876 or a system clock. One MAX1875/MAX1876 can be set to generate an in-phase, or 90° out-of-phase, clock signal for synchronization with additional controllers. This allows two controllers to operate either as an interleaved two- or four-phase system with each output shifted by 90°. These devices also feature soft-start and soft-stop.

The MAX1875/MAX1876 eliminate the need for current-sense resistors by utilizing the low-side MOSFET's on-resistance as a current-sense element. This protects the DC-DC components from damage during output- overload conditions or when output short-circuit faults without requiring a current-sense resistor. Adjustable foldback current limit reduces power dissipation during short-circuit conditions. The MAX1876 includes a power-on reset output to signal the system when both outputs reach regulation.

The MAX1875/MAX1876 are available in a 24-pin QSOP package. An evaluation kit is available to speed designs.

Key Features

  • Two Independent Output Voltages
  • 180° Out-of-Phase Operation
  • 90° Out-of-Phase Operation (Using Two MAX1875/MAX1876s)
  • Foldback Current Limit
  • 4.75V to 23V Input Supply Range
  • 0 to 18V Output-Voltage Range (Up to 10A)
  • >90% Efficiency
  • Fixed-Frequency Pulse-Width Modulation (PWM) Operation
  • Adjustable 100kHz to 600kHz Switching Frequency
  • External SYNC Input
  • Clock Output for Master/Slave Synchronization
  • Soft-Start and Soft-Stop
  • Active-low RST Output with 140ms Minimum Delay (MAX1876)
  • Lossless Current Limit (No Sense Resistor)
  • Applications/Uses

    • Broadband Routers
    • DSP, ASIC, and FPGA Power Supplies
    • Network-Power Supplies
    • Servers
    • Set-Top Boxes
    • Telecom Power Supplies
    Parametric specs for Step-Down Switching Regulators
    VIN (V) (min) 4.75
    VIN (V) (max) 23
    VOUT1 (V) (min) 1
    VOUT1 (V) (max) 18
    IOUT1 (A) (max) 10
    Switch Type External
    Output Adjust. Method Resistor
    Synchronous Switching? Yes
    # DC-DC Outputs 2
    Switching Frequency (kHz) 600
    Package/Pins QSOP/24
    Budgetary
    Price (See Notes)
    $3.36 @1k
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    Simplified Block Diagram

    MAX1875, MAX1876: Typical Operating Circuit MAX1875, MAX1876: Typical Operating Circuit Zoom icon

    Technical Docs

    Design & Development

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    Parameters

    Parametric specs for Step-Down Switching Regulators
    VIN (V) (min) 4.75
    VIN (V) (max) 23
    VOUT1 (V) (min) 1
    VOUT1 (V) (max) 18
    IOUT1 (A) (max) 10
    Switch Type External
    Output Adjust. Method Resistor
    Synchronous Switching? Yes
    # DC-DC Outputs 2
    Switching Frequency (kHz) 600
    Package/Pins QSOP/24
    Budgetary
    Price (See Notes)
    $3.36 @1k

    Key Features

  • Two Independent Output Voltages
  • 180° Out-of-Phase Operation
  • 90° Out-of-Phase Operation (Using Two MAX1875/MAX1876s)
  • Foldback Current Limit
  • 4.75V to 23V Input Supply Range
  • 0 to 18V Output-Voltage Range (Up to 10A)
  • >90% Efficiency
  • Fixed-Frequency Pulse-Width Modulation (PWM) Operation
  • Adjustable 100kHz to 600kHz Switching Frequency
  • External SYNC Input
  • Clock Output for Master/Slave Synchronization
  • Soft-Start and Soft-Stop
  • Active-low RST Output with 140ms Minimum Delay (MAX1876)
  • Lossless Current Limit (No Sense Resistor)
  • Applications/Uses

    • Broadband Routers
    • DSP, ASIC, and FPGA Power Supplies
    • Network-Power Supplies
    • Servers
    • Set-Top Boxes
    • Telecom Power Supplies

    Description

    The MAX1875/MAX1876 dual, synchronized, step-down controller generates two outputs from input supplies ranging from 4.75V to 23V. Each output is adjustable from sub-1V to 18V and supports loads of 10A or higher. Input voltage ripple and total RMS input ripple current are reduced by synchronized 180° out-of-phase operation.

    The switching frequency is adjustable from 100kHz to 600kHz with an external resistor. Alternatively, the controller can be synchronized to an external clock generated to another MAX1875/MAX1876 or a system clock. One MAX1875/MAX1876 can be set to generate an in-phase, or 90° out-of-phase, clock signal for synchronization with additional controllers. This allows two controllers to operate either as an interleaved two- or four-phase system with each output shifted by 90°. These devices also feature soft-start and soft-stop.

    The MAX1875/MAX1876 eliminate the need for current-sense resistors by utilizing the low-side MOSFET's on-resistance as a current-sense element. This protects the DC-DC components from damage during output- overload conditions or when output short-circuit faults without requiring a current-sense resistor. Adjustable foldback current limit reduces power dissipation during short-circuit conditions. The MAX1876 includes a power-on reset output to signal the system when both outputs reach regulation.

    The MAX1875/MAX1876 are available in a 24-pin QSOP package. An evaluation kit is available to speed designs.

    Simplified Block Diagram

    MAX1875, MAX1876: Typical Operating Circuit MAX1875, MAX1876: 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