Datasheet > LM2638

LM2638

更新时间： 2024-09-08 00:01:07

品牌	Logo	应用领域
美国国家半导体 - NSC		开关控制器
页数	文件大小	规格书
9页	162K
描述
Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two Linear Regulator Controllers

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LM2638 数据手册

May 1999

LM2638

Motherboard Power Supply Solution with a 5-Bit

Programmable Switching Controller and Two Linear

Regulator Controllers

Both linear controllers have under voltage latch-off.

General Description

The LM2638 provides a comprehensive embedded power

Features

n Provides 3 regulated voltages

n Power Good flag and output enable

n Charge pump pin

Switching Section

n Synchronous rectification

n 5-bit DAC programmable down to 1.3V

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.

n Typical 1% DAC tolerance

n Switching frequency: 50 kHz to 1 MHz

n 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 drive capability

n Ultra fast response speed

Switching Section — The switching regulator controller fea-

tures an Intel-compatible, 5-bit programmable output volt-

age, 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 pro-

vides accurate over-current protection with the use of an ex-

ternal sense resistor. The other saves cost by taking advan-

tage of the r_{DS_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.

n Under voltage latch-off at 0.63V

n Output voltages default to 1.5V and 2.5V yet adjustable

Applications

n Embedded power supplies for motherboards

n Triple DC/DC power supplies

Linear Section — The two linear regulator controllers fea-

ture wide control bandwidth, N-FET and NPN transistor driv-

ing 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.

n Programmable high current DC/DC power supply

Pin Configuration

24-Lead SOIC

DS101034-1

Top View

Order Number LM2638M

See NS Package Number M24B

™

M II is a trademark of Cyrix Corporation a wholly owned subsidiary of National Semiconductor Corporation.

™

Pentium is a trademark of Intel Corporation.

™

K6 is a trademark of Advanced Micro Devices, Inc.

DS101034

www.national.com

12 3 4 5 6 7...9

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与LM2638相关器件

型号	品牌	获取价格	描述	数据表
LM2638M	NSC	获取价格	Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two L
LM2638M/NOPB	TI	获取价格	SWITCHING CONTROLLER, 286kHz SWITCHING FREQ-MAX, PDSO24, SOIC-24
LM2638MX	TI	获取价格	LM2638 Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller an
LM2639	NSC	获取价格	5-Bit Programmable, High Frequency Multi-phase PWM Controller
LM2639M	NSC	获取价格	5-Bit Programmable, High Frequency Multi-phase PWM Controller
LM2639M/NOPB	TI	获取价格	SWITCHING CONTROLLER, 8700kHz SWITCHING FREQ-MAX, PDSO24, PLASTIC, SOIC-24
LM2639MDC	NSC	获取价格	IC SWITCHING CONTROLLER, 8700 kHz SWITCHING FREQ-MAX, UUC, DIE, Switching Regulator or Con
LM2639MWC	NSC	获取价格	IC SWITCHING CONTROLLER, 8700 kHz SWITCHING FREQ-MAX, UUC, WAFER, Switching Regulator or C
LM2639MX	ETC	获取价格	Voltage-Mode SMPS Controller
LM2640	NSC	获取价格	Dual Adjustable Step-Down Switching Power Supply Controller

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