Motherboard Power Supply Solution With A 5-Bit Programmable Switching Controller And Two Linear Regulator Controllers

The LM2638 provides a comprehensive embedded power supply solution for motherboards hosting high performance MPUs such as Pentium? II, M II?, K6?-2 and other similar high performance MPUs. The LM2638 incorporates a 5-bit programmable, synchronous buck switching controller and two high-speed linear Regulator controllers in a 24-pin SO package. In a typical application, the switching controller supplies the MPU core, and the linear Regulator controllers supply the GTL+ bus and the Clock or graphics chip core. A Charge Pump pin helps provide the necessary voltage to power the linear sections when 12V is shut off during system standby such as STR mode.
Switching Section - The Switching Regulator controller features an Intel-compatible, 5-bit programmable output voltage, over-current and over-voltage protection, a power good signal, and a logic-controlled output enable. 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[lowbar]ON of the high-side FET When there is an over voltage, the controller turns off the high side FET and turns on the low side.
Linear Section - The two linear Regulator controllers feature wide control bandwidth, N-FET and NPN Transistor driving capability and an adjustable output. The wide control bandwidth makes meeting the GTL+ bus transient response requirement an easy job. In minimum configuration, the two controllers default to 1.5V and 1.25V respectively.
Both linear controllers have under voltage latch-off.
By National Semiconductor Corporation
LM2638 's PackagesLM2638 's pdf datasheet

LM2638 Pinout, Pinouts
LM2638 pinout,Pin out
This is one package pinout of LM2638,If you need more pinouts please download LM2638's pdf datasheet.

LM2638 Application circuits
LM2638 circuits
This is one application circuit of LM2638,If you need more circuits,please download LM2638's pdf datasheet.

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