Dual Power-Supply Controller - Maxim Integrated Products
Description
19-3569; Rev 2; 4/07 EVAALVUAAILTAIOBNLEKIT
Interleaved High-Efficiency, Dual Power-Supply Controllers for Notebook Computers
MAX8716/MAX8717/MAX8756/MAX8757
General Description
The MAX8716/MAX8717/MAX8756/MAX8757 are dual, step-down, interleaved, fixed-frequency, switch-mode power-supply (SMPS) controllers with synchronous rectification.
The MAX8716/MAX8717/MAX8756/MAX8757 are intended for main (5V/3.
3V) power generation, while the MAX8756 is optimized for I/O power rails in batterypowered systems.
Fixed-frequency operation with optimal interleaving minimizes input ripple current from the lowest input voltages up to the 26V maximum input.
Optimal 40/60 interleaving allows the input voltage to go down to 8.
3V before duty-cycle overlap occurs in 5V/3.
3V applications, compared to 180° out-of-phase regulators where the dutycycle overlap occurs when the input drops below 10V.
Accurate output current limit is achieved using a sense resistor.
Alternatively, power dissipation can be reduced using lossless inductor current sensing.
Independent ON/OFF controls and power-good signals allow flexible power sequencing.
Soft-start reduces inrush current, while soft-stop gradually ramps the output voltage down preventing negative voltage dips.
A low-noise mode maintains high light-load efficiency while keeping the switching frequency out of the audible range.
The MAX8716 is available in a 24-pin thin QFN package, and the MAX8717/MAX8756/MAX8757 are available in a 28-pin thin QFN package.
Applications
2 to 4 Li+ Cell Battery-Powered Devices
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
Main or I/O Power Supplies
Dual Mode is a trademark of Maxim Integrated Products, Inc.
Features
o Fixed Switching Frequency 200kHz, 300kHz, or 500kHz 250kHz, 300kHz, or 400kHz (MAX8756 Only)
o No Current-Sense Resistor Required
o 40/60 Optimal Interleaving
o Reduced Input-Capacitor Requirement
o Output Voltage Fixed or Adjustable Outputs (Dual Mode™) 3.
3V/5V Fixed or 1V to 5.
5V ...
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