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LM2640 参数 Datasheet PDF下载

LM2640图片预览
型号: LM2640
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文件页数/大小: 18 页 / 506 K
品牌: ETC [ ETC ]
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LM2640 Dual Adjustable Step-Down Switching Power Supply Controller
May 2001
LM2640
Dual Adjustable Step-Down Switching Power Supply
Controller
General Description
The LM2640 is a dual step-down power supply controller
intended for application in notebook personal computers and
other battery-powered equipment.
Fixed-frequency synchronous drive of logic-level N-channel
power MOSFETs is combined with an optional
pulse-skipping mode to achieve ultra efficient power conver-
sion over a 1000:1 load current range. The pulse-skipping
mode can be disabled in favor of fixed-frequency operation
regardless of the load current level.
High DC gain and current-mode feedback control assure
excellent line and load regulation and a wide loop bandwidth
for fast response to dynamic loads.
An internal oscillator fixes the switching frequency at
200 kHz. Optionally, switching can be synchronized to an
external clock running as fast as 400 kHz.
An optional soft-start feature limits current surges from the
input power supply at start up and provides a simple means
of start-up sequencing.
Logic-level inputs allow the controllers to be turned ON and
OFF separately.
Key Specifications
n
n
n
n
n
96% efficient
5.5 to 30V input range
Dual outputs adjustable from 2.2 to 6V
0.5% typical load regulation error
0.002%/V typical line regulation error
Features
n
200 kHz fixed-frequency switching
n
Switching synchronization with an external signal up to
400 kHz
n
Optional pulse-skipping mode
n
Adjustable secondary feedback
n
Input undervoltage lockout
n
Output undervoltage shutdown protection
n
Output overvoltage shutdown protection
n
Programmable soft-start (each controller)
n
5V, 50 mA linear regulator output
n
Precision 2.5V reference output
n
28-pin TSSOP
Applications
n
Notebook and subnotebook computers
n
Wireless data terminals
n
Battery-powered instruments
Connection Diagram and Ordering Information
28-Lead TSSOP (MTC)
10014801
Top View
Order Number LM2640MTC-ADJ
See NS Package Number MTC28
© 2001 National Semiconductor Corporation
DS100148
www.national.com