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參數資料
| 型號： | 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溝道場效應管同步降壓穩壓控制器，用于從3.3V轉換 |
| 文件頁數： | 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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相關代理商/技術參數 |
參數描述 |
|---|---|
| LM2743-19AEVAL | 功能描述:電源管理IC開發工具 LM2743 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM2743EVAL | 功能描述:BOARD EVALUATION LM2743 RoHS:否 類別:編程器，開發系統 >> 評估板 - DC/DC 與 AC/DC（離線）SMPS 系列:PowerWise® 產品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:True Shutdown™ 主要目的:DC/DC，步升 輸出及類型:1，非隔離 功率 - 輸出:- 輸出電壓:- 電流 - 輸出:1A 輸入電壓:2.5 V ~ 5.5 V 穩壓器拓撲結構:升壓 頻率 - 開關:3MHz 板類型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| LM2743EVAL/NOPB | 功能描述:電源管理IC開發工具 LM2743 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM2743MTC | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| LM2743MTC/NOPB | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
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