HIGH_EFFICIENCY_TRIPLE_OUTPUT_SUPPLY_FOR_NOTEBOOK_COMPUTERS

Published:2009/6/24 2:37:00 Author:Jessie | From:SeekIC

The circuit is conftgured to provide output voltages of 3.3 V, 5 V, and 12 V. The current capability of both the 3.3-V and 5-V outputs is 2 A (2.5 A peak). The logic controlled 12-V output can provide 150 mA (200 mA peak), which is ideal for flash memory applications. The operating efficiency shown in the ftgure exceeds 90% for both the 3.3-V and 5-V sections.The 3.3-V section for the circuit in the figure is comprised of the main switch Q4, synchronous switch Q5, inductor L1, and current shunt RSENSE. Current-sense resistor RSENSE monitors the inductor current and is used to set the output current accord-ing to the formula OUT = 100 mV/RSENSE. Advantages of current control include excellent line and load transient rejection, inher-ent short-circuit protection, and controlled start-up currents. Peak inductor currents for L1 and T1 for the circuit in the figure are limited to 150 mV/RSENSE or 3.0 A and 3.75 A, respectively.



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