Motherboard Power Supply Solution With A 5-Bit Programmable Switching Controller And Two Linear Regulator Controllers
The LM2637 provides a comprehensive 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.
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 rDS_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 and 2.5V respectively.
Both linear controllers have under voltage latch-off.
By National Semiconductor Corporation
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