LM2633

LM2633 Advanced Two-Phase Synchronous Triple Regulator Controller for Notebook CPUs August 2001 LM2633 Advanced Two-Phase Synchronous Triple Regulator Controller for Notebook CPUs General Description The LM2633 is a feature-rich IC that combines three regulator controllers - two current mode synchronous buck regulator controllers and a linear regulator controller. The two switching regulator controllers operate 180˚ out of phase. This feature reduces the input ripple RMS current, resulting in a smaller input filter. The first switching controller (Channel 1) features an Intel mobile CPU compatible precision 5-bit digital-to-analog converter which programs the output voltage from 0.925V to 2.00V. It is also compatible with the dynamic VID requirements. The second switching controller (Channel 2) is adjustable between 1.25V to 6.0V. Use of synchronous rectification and pulse-skip operation at light load achieves high efficiency over a wide load range. Fixed-frequency operation can be obtained by disabling the pulse-skip mode. Current-mode feedback control assures excellent line and load regulation and a wide loop bandwidth for good response to fast load transient events. Current mode control is achieved through sensing the Vds of the top FET and thus an external sense resistor is not necessary. A power good signal is available to indicate the general health of the output voltages. A unique feature is the analog soft-start for the switching controllers is independent of the sl...