High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers
SUNNYVALE, CA-November 12, 2004-Maxim Integrated Products (NASDAQ: MXIM) introduces the MAX1533/MAX1537, dual, step-down, switch-mode power-supply (SMPS) controllers with synchronous rectification for main 5V/3.3V power generation in battery-powered systems. Fixed-frequency operation with optimal interleaving minimizes input ripple current from the lowest input voltage up to the 26V maximum input. Using a sense resistor, output current sensing provides an accurate current limit. Alternatively, power dissipation can be reduced using loss-less inductor current sensing.
Internal 5V and 3.3V linear regulators power the MAX1533/MAX1537 and their gate drivers, as well as external keep-alive loads to a total of 100mA. When the main PWM regulators are in regulation, automatic bootstrap switches bypass the internal linear regulators and provide currents up to 200mA from each linear output. The MAX1537 features an additional adjustable, internal 150mA linear regulator typically used with a secondary winding to provide a 12V supply. The MAX1533/MAX1537 include on-board power-up sequencing, a power-good (PGOOD) output, digital soft-start, and an internal soft-shutdown output discharge that prevents negative voltages on shutdown.
Both the MAX1533 and MAX1537 offer optional inductor-saturation protection, and overvoltage/undervoltage protection. The MAX1533 is available in a 32-pin TQFN package, while the MAX1537 is available in a 36-pin TQFN package. The MAX1533/MAX1537 are screened for the industrial temperature range (-40 degrees Celsius to +85 degrees Celsius). MAX1533 prices start at $5.10 (1000-up, FOB USA), and the MAX1537 prices start at $5.20 (1000-up, FOB USA). Pre-assembled MAX1533EVKIT and MAX1537EVKIT evaluation kits are available with recommended external components to speed designs.
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