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參數資料
| 型號： | LM5000-3MTCX/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2.7 A SWITCHING REGULATOR, 840 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | TSSOP-16 |
| 文件頁數： | 2/18頁 |
| 文件大?。?/td> | 388K |
| 代理商： | LM5000-3MTCX/NOPB |
Operation
20031902
FIGURE 3. Simplified Boost Converter Diagram
(a) First Cycle of Operation (b) Second Cycle Of Operation
CONTINUOUS CONDUCTION MODE
The LM5000 is a current-mode, PWM regulator. When used
as a boost regulator the input voltage is stepped up to a higher
output voltage. In continuous conduction mode (when the in-
ductor current never reaches zero at steady state), the boost
regulator operates in two cycles.
In the first cycle of operation, shown in Figure 3 (a), the tran-
sistor is closed and the diode is reverse biased. Energy is
collected in the inductor and the load current is supplied by
C
OUT.
The second cycle is shown in Figure 3 (b). During this cycle,
the transistor is open and the diode is forward biased. The
energy stored in the inductor is transferred to the load and
output capacitor.
The ratio of these two cycles determines the output voltage.
The output voltage is defined approximately as:
where D is the duty cycle of the switch, D and D
′ will be re-
quired for design calculations.
SETTING THE OUTPUT VOLTAGE
The output voltage is set using the feedback pin and a resistor
divider connected to the output as shown in Figure 1. The
feedback pin is always at 1.259V, so the ratio of the feedback
resistors sets the output voltage.
INTRODUCTION TO COMPENSATION
20031905
FIGURE 4. (a) Inductor current. (b) Diode current.
The LM5000 is a current mode PWM regulator. The signal
flow of this control scheme has two feedback loops, one that
senses switch current and one that senses output voltage.
To keep a current programmed control converter stable
above duty cycles of 50%, the inductor must meet certain cri-
teria. The inductor, along with input and output voltage, will
determine the slope of the current through the inductor (see
www.national.com
10
LM5000
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| LM5000-3MYC | 制造商:Texas Instruments 功能描述: |
| LM5000EP | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Enhanced Plastic High Voltage Switch Mode Regulator |
| LM5000EVAL | 功能描述:電源管理IC開發(fā)工具 LM5000 EVAL UNIT 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 |
| LM5000EVAL/NOPB | 功能描述:EVALUATION BOARD FOR LM5000 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - DC/DC 與 AC/DC（離線）SMPS 系列:- 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(wěn)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 |
| LM5000SD-3 | 功能描述:直流/直流開關轉換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
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