LM3207TL-2.53 National Semiconductor, LM3207TL-2.53 Datasheet - Page 20

• Manufacturer Part Number: LM3207TL-2.53
• Description: LM3207 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers with Integrated Vref LDO; Package: MICRO SMD; No of Pins: 9; Qty per Container: 250; Container: Reel
• Manufacturer: National Semiconductor

www.national.com
plastic encapsulation characteristic of larger devices, it is vul-
nerable to light. Backside metalization and/or epoxy coating,
along with front-side shading by the printed circuit board, re-
duce this sensitivity. However, the package has exposed die
BOARD LAYOUT CONSIDERATIONS
Referring to Figure 4, the LM3207 has two major current loops
where pulse and ripple current flow. The loop shown in the
left hand side is most important, because pulse current shown
in Figure 4 flows in this path. The right hand side is next. The
current waveform in this path is triangular, as shown in Figure
4. Pulse current has many high-frequency components due
to fast di/dt. Triangular ripple current also has wide high-fre-
FIGURE 4. Current Loop
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edges. Micro SMD devices are sensitive to light, in the red
and infrared range, shining on the package’s exposed die
edges.
quency components. Board layout and circuit pattern design
of these two loops are the key factors for reducing noise ra-
diation and stable operation. Other lines, such as from battery
to C1(+) and C2(+) to load, are almost DC current, so it is not
necessary to take so much care. Only pattern width (current
capability) and DCR drop considerations are needed.
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