參數(shù)資料
型號(hào): AN1071
廠商: Electronic Theatre Controls, Inc.
元件分類: 圓形連接器
英文描述: Circular Connector; No. of Contacts:6; Series:MS27508; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:8; Circular Contact Gender:Pin; Circular Shell Style:Box Mount Receptacle; Insert Arrangement:8-35 RoHS Compliant: No
中文描述: 信息關(guān)于LM2650評(píng)估板
文件頁數(shù): 1/6頁
文件大?。?/td> 77K
代理商: AN1071
Information About the
LM2650 Evaluation Board
Rev. 1
INTRODUCTION
A printed circuit board (PCB) has been developed. This ap-
plication note contains information about the board.
GENERAL DESCRIPTION
The LM2650 evaluation board is provided as a tool for devel-
oping DC/DC converters based on the LM2650 IC. It is con-
figured for single-output, step-down DC/DC converters. Fig-
ure 1 is a complete schematic of the board which can
accommodate up to 28 components including the LM2650.
Table 1 is a complete list of pads for placing components.
Note:
Not all applications will require the placement of all 28
components. The number of components placed depends
on the requirements of the application and the use of fea-
tures like programmable soft-start. The LM2650 evaluation
board is intended to be a reusable tool on which many differ-
ent converters meeting the requirements of many different
applications can be built. It is not intended to demonstrate
only one application of the LM2650.
For convenience, a sample of the LM2650 and eight other
components have been assembled: a 0.1 μF capacitor at
each of C1, C2, C6, and CB, a 0.2 μF capacitor at CVDD, a
0.01 μF capacitor at CSS, a 24.9 k
resistor at R2, and a 0
resistor at R4. Of the eight, the first seven are common to
many applications, and the last is simply a jumper grounding
the SYNC input. When the synchronization feature is not be-
ing used, the SYNC input should be grounded.
EXAMPLE CIRCUITS
The components contained in Tables 2, 3, and 4 can be used
to build typical application circuits. As with the design of any
DC/DC converter, the design of these involved tradeoffs be-
tween efficiency, size, and cost. The converters detailed in
Table 2 were designed with efficiency as the number one cri-
teria. Those detailed in Table 4 trade slightly higher switching
losses for a much smaller inductor.
THERMAL PERFORMANCE
The 24-lead SO package is a molded plastic package with a
solid copper lead frame. Most of the heat generated at the
die flows through the lead frame into the 3-ounce copper
planes on the board. The board then acts as a heat sink. The
junction-to-ambient thermal resistance of the packaged IC
mounted on the board has been measured to be 38C/W, 37
C/W, and 35 C/W for the dissipation of 1.0W, 1.5W, and
2.0W respectively. These measurements were made in still
air. The junction-to-ambient thermal resistance of the pack-
aged IC alone in still air is 78C/W. The board is 0.063
thick
FR-4 material.
ART
Figure 2 through Figure 4 show the PCB art work.
AN100011-5
FIGURE 1. The LM2650 Evaluation Board Rev. 1 Schematic
National Semiconductor
AN-1071
Steven Hunt
September 1997
I
A
1997 National Semiconductor Corporation
AN100011
www.national.com
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