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參數資料
| 型號： | LM5026SDX |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩壓器 |
| 英文描述： | Active Clamp Current Mode PWM Controller |
| 中文描述： | 3 A SWITCHING CONTROLLER, 660 kHz SWITCHING FREQ-MAX, DSO16 |
| 封裝： | 5 X 5 MM, EXPOSED PAD, LLP-16 |
| 文件頁數： | 20/23頁 |
| 文件大?。?/td> | 936K |
| 代理商： | LM5026SDX |
Applications Information
(Continued)
and the RT pins should be as physically close as possible to
the IC, thereby minimizing noise pickup on the PC board
tracks.
Layout considerations are critical for the current sense filter.
If a current sense transformer is used, both leads of the
transformer secondary should be routed to the sense filter
components and to the IC pins. The ground side of each
transformer should be connected via a dedicated PC board
track to the AGND pin, rather than through the ground plane.
If the current sense circuit employs a sense resistor in the
drive transistor source, low inductance resistor should be
used. In this case, all the noise sensitive low current ground
tracks should be connected in common near the IC, and then
a single connection made to the power ground (sense resis-
tor ground point). The gate drive outputs of the LM5026
should have short direct paths to the power MOSFETs in
order to minimize inductance in the PC board traces.
The two ground pins (AGND, PGND) must be connected
together with a short direct connection to avoid jitter due to
relative ground bounce.
If the internal dissipation of the LM5026 produces high junc-
tion temperatures during normal operation, the use of mul-
tiple vias under the IC to a ground place can help conduct
heat away from the IC. Judicious positioning of the PC board
within the end product, along with use of any available air
flow (forced or natural convection) can help reduce the junc-
tion temperatures.
Application Circuit Example
The following schematic shows an example of an LM5026
controlled 100W active clamp forward power converter. The
input voltage range (V
PWR
) is 36V to 78V, and the output
voltage is 3.3V. The output current capability is 30 Amps.
Current sense transformer T2 provides information to the CS
pin for current mode control and current limit protection. The
error amplifiers and reference U3 and U4 provide voltage
feedback via optocoupler U2. Synchronous rectifiers Q3-Q6
minimize rectification losses in the secondary. An auxiliary
winding on inductor L2 provides power to the LM5026 VCC
pin when the output is in regulation. The input voltage UVLO
levels are
≈
34V for increasing V
, and
≈
32V for decreas-
ing V
. The circuit can be shut down by forcing the
ON/OFF input (J2) below 1.25V. An external synchronizing
frequency can be applied to the SYNC input (J11) or like
converters can be self-synchronized by connections of (J3).
The regulator output is current limited at
≈
32A.
L
www.national.com
20
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LM5026SDX/NOPB | 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| LM5027 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Voltage Mode Active Clamp Controller |
| LM5027A | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Evaluation Board evaluation board is designed to provide |
| LM5027A-EVAL/NOPB | 功能描述:電源管理IC開發工具 LM5027A EVAL BRD 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 |
| LM5027AMH/NOPB | 功能描述:電壓模式 PWM 控制器 Active Clamp Pwm W/3A Sr Drv RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
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