LM2637 Datasheet | National Semiconductor

Description The LM2637 provides a prehensive embedded power supply solution for motherboards hosting high performance MPUs such as M II™, Pentium™ II, K6-2 and other similar high performance MPUs. The LM2637 incorporates a 5-bit programmable, synchronous buck switching controller and two high-speed linear regulator controllers in a 24-pin SO package. Both linear controllers have under voltage latch-off. Features n Provides 3 regulated voltages n Power Good flag and output enable n Under-voltage latch-off Switching Section n Synchronous rectification n 5-bit DAC programmable from 3.5V to 1.3V n Typical 1% DAC tolerance n Switching frequency: 50 k Hz to 1 MHz n Two levels of over-voltage protection n Two methods of over-current protection n Adaptive non-overlapping FET gate drives n Soft start without external capacitor Linear Section n N-FET and NPN driving capability n Ultra fast response speed n Output voltages default to 1.5V and 2.5V yet adjustable Switching Section - The switching regulator controller features a 5-bit programmable DAC, over-current and over-voltage protection, under-voltage latch-off, a power good signal, and output enable. The 5-bit DAC has a typical tolerance of 1%. There are two user-selectable over-current protection methods. One provides accurate over-current protection with the use of an external sense resistor. The other saves cost by taking advantage of the r DS_ON of the high-side FET. The over voltage protection provides two levels of protection. The first level keeps the high-side FET off and the low-side FET on. The second provides a gate signal that can be used to fire an external SCR. Linear Section - The two linear regulator controllers feature wide control bandwidth, N-FET and NPN transistor driving capability, and an adjustable output voltage. The wide control bandwidth makes meeting fast load transient response requirement such as that of the GTL+ bus an easy job. In minimum configuration, the two controllers default to 1.5V...