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Dual 180° Out-of-Phase Buck Controllers with Sequencing/Prebias Startup and POR

Product Details

Key Features

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 4.5
VIN (V) (max) 23
VOUT1 (V) (min) 0.8
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)
4.12
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Simplified Block Diagram

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Parameters

Parametric specs for Step-Down Switching Regulators
VIN (V) (min) 4.5
VIN (V) (max) 23
VOUT1 (V) (min) 0.8
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)
4.12

Key Features

  • 4.5V to 23V Input Supply Range
  • 0 to 18V Output Voltage Range (Up to 10A)
  • Adjustable Lossless Foldback Current Limit
  • Adjustable 100kHz to 600kHz Switching Frequency
  • Optional Synchronization
  • Clock Output for Master/Slave Synchronization
  • 4 x 90° Out-of-Phase Step-Down Converters (Using Two Controllers, Figure 7)
  • Prebias Startup (MAX1875A/MAX1876A)
  • Power Sequencing (MAX1858A)
  • RST-bar Output with 140ms Minimum Delay (MAX1858A/MAX1876A)
  • Fixed-Frequency Pulse-Width Modulation (PWM) Operation

Applications/Uses

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

Description

The MAX1858A/MAX1875A/MAX1876A dual, synchronized, step-down controllers generate two outputs from input supplies ranging from 4.5V 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 by another MAX1858A/MAX1875A/MAX1876A or a system clock. One MAX1858A/MAX1875A/MAX1876A 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°. The MAX1858A/MAX1875A/MAX1876A feature soft-start. The MAX1858A also features first-on/last-off power sequencing and soft-stop.

The MAX1858A/MAX1875A/MAX1876A 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 output short-circuit faults without requiring a current-sense resistor. Adjustable foldback current limit reduces power dissipation during short-circuit conditions. The MAX1858A/MAX1876A include a power-on reset (POR) output to signal the system when both outputs reach regulation.

The MAX1858A/MAX1875A/MAX1876A ensure that the output voltage does not swing negative when the input power is removed or when EN is driven low. The MAX1875A/MAX1876A also allow prebias startup without discharging the output.

The MAX1858A/MAX1875A/MAX1876A are available in a 24-pin QSOP package. Use the MAX1875 evaluation kit or the MAX1858 evaluation kit to evaluate the MAX1858A/MAX1875A/MAX1876A.

Simplified Block Diagram

MAX1858A, MAX1875A, MAX1876A: Functional Diagram MAX1858A, MAX1875A, MAX1876A: 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 .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.