Advanced Two-phase Synchronous Triple Regulator Controller For Notebook Cpus - National Semiconductor

The LM2633 is a feature-rich IC that combines three regu- lator controllers - two current mode synchronous buck regu- lator 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 con- verter which programs the output voltage from 0.925V to 2.00V. It is also compatible with the dynamic VID require- ments. The second switching controller (Channel 2) is ad- justable 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 re- sponse 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 slew rate of the input volt- age. This will make the soft start behavior more predictable and controllable. An internal 5V rail is available externally for boot-strap circuitry (only) when no 5V is available from other sources. By National Semiconductor Corporation