SMPS Controllers Breath Life Into Notebooks December 2004 Issue Published Date: January 06, 2005
Managing power in notebook computers and other battery-powered systems, the MAX1533 and MAX1537, dual, step-down, switch-mode power-supply (SMPS) controllers employ synchronous rectification to generate regulated 5V/3.3V outputs. Both devices rely on fixed-frequency operation with interleaving to minimize ripple current across the input range up to 26V. When their main PWM regulators are in regulation, automatic bootstrap switches bypass the internal linear regulators and provide currents up to 200 mA from each output. The MAX1537 includes an additional adjustable 150-mA linear regulator for use with a secondary winding to provide a 12V supply. Other shared features include power-up sequencing, a power-good output, digital soft-start, and a soft shutdown output discharge. Options include inductor-saturation, over-voltage, and under-voltage protection. The MAX1533 comes in a 32-pin TQFN, and the MAX1537 in a 36-pin TQFN. Prices start at $5.10 and $5.20 each/1,000, respectively. MAXIM INTEGRATED PRODUCTS, Sunnyvale, CA. (800) 998-8800.
