參數(shù)資料
型號(hào): LM2743
廠商: National Semiconductor Corporation
英文描述: N-Channel FET Synchronous Buck Regulator Controller for Conversion from 3.3V
中文描述: N溝道場效應(yīng)管同步降壓穩(wěn)壓控制器,用于從3.3V轉(zhuǎn)換
文件頁數(shù): 9/23頁
文件大小: 653K
代理商: LM2743
Block Diagram
20095203
Application Information
THEORY OF OPERATION
The LM2743 is a voltage-mode, high-speed synchronous
buck regulator with a PWM control scheme. It is designed for
use in set-top boxes, thin clients, DSL/Cable modems, and
other applications that require high efficiency buck convert-
ers. It has power good (PWGD) flag, output shutdown (SD),
UVLO mode, and over-voltage flag (OVF) and under- volt-
age flag (UVF) features. The over-voltage and under-voltage
signals are OR gated to drive the power good signal. If this
signal is pulled low, the high side is off and low side if on, but
only if the duty cycle is less then maximum. Current limit is
achieved by sensing the voltage V
across the low side
FET. During current limit the high side gate is turned off and
the low side gate is turned on. A 90μA source discharges the
soft start capacitor (reducing max. duty cycle) until the cur-
rent is under control.
START UP
When V
exceeds 2.76V and the shutdown pin (SD) sees
a logic high, the internal fixed 10μA source begins charging
the soft start capacitor. During this time the output of the
error amplifier is allowed to rise with the voltage of the soft
start capacitor. This capacitor, C
SS
, determines soft start
time, and can be calculated approximately by:
During soft start the power good flag is forced low and it is
released when the voltage reaches a set value as shown in
Figure 1
. At this point the chip enters normal operation
mode, the power good flag is released, and the OVF and
UVF functions begin to monitor V
OUT
.
L
www.national.com
9
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參數(shù)描述
LM2743-19AEVAL 功能描述:電源管理IC開發(fā)工具 LM2743 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
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