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參數(shù)資料
| 型號(hào)： | LM3204TL |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Miniature, Adjustable, Step-Down DC-DC Converter with Bypass Mode for RF Power Amplifiers |
| 中文描述： | 0.94 A SWITCHING REGULATOR, 2200 kHz SWITCHING FREQ-MAX, PBGA10 |
| 封裝： | ROHS COMPLIANT, THIN MICRO SMD, 10 PIN |
| 文件頁數(shù)： | 14/16頁 |
| 文件大?。?/td> | 874K |
| 代理商： | LM3204TL |
Application Information
(Continued)
If V
voltage is less than 0.267V (V
= 0.8V), the output
voltage may not be regulated due to the required on-time
being less than the minimum on-time (50ns). The output
voltage can go lower than 0.8V providing a limited V
range
is used. Refer to datasheet curve (Low V
Voltage vs
Output Voltage) for details. This curve is for a typical part and
there could be part to part variation for output voltages less
than 0.8V over the limited V
IN
range. In addition, if the V
CON
is less than approximately 0.15V, the LM3204 output is
turned off, but the internal bias circuits are still active.
INDUCTOR SELECTION
A2.2μH inductor with saturation current rating over 940mAis
recommended for almost all applications. The inductor resis-
tance should be less than 0.3
for better efficiency.
Table 1
lists suggested inductors and suppliers.
TABLE 1. Suggested Inductors and Their Suppliers
Model
Size (WxLxH) [mm]
3.3 x 3.3 x 1.4
2.6 x 2.8 x 1.0
3.0 x 3.0 x 1.0
Vendor
Coilcraft
TDK
Taiyo-Yuden
DO3314-222MX
VLF3010AT-2R2M1R0
NR3010T2R2M
If a higher value inductor is used the LM3204 may become
unstable and exhibit large under or over shoot during line,
load and V
transients. If smaller inductance value is
used, slope compensation maybe insufficient causing sub-
harmonic oscillations. The device has been tested with in-
ductor values in the range 1.55μH to 3.1μH to account for
inductor tolerances.
For low-cost applications, an unshielded bobbin inductor can
be used. For noise-critical applications, an unshielded or
shielded-bobbin inductor should be used. A good practice is
to layout the board with footprints accommodating both
types for design flexibility. This allows substitution of an
unshielded inductor, in the event that noise from low-cost
bobbin models is unacceptable. Saturation occurs when the
magnetic flux density from current through the windings of
the inductor exceeds what the inductor’s core material can
support with a corresponding magnetic field. This can cause
poor efficiency, regulation errors or stress to a DC-DC con-
verter like the LM3204.
CAPACITOR SELECTION
The LM3204 is designed to be used with ceramic capacitors.
Use a 10μF ceramic capacitor for the input and a 4.7μF
ceramic capacitor for the output. Ceramic capacitors such as
X5R, X7R and B are recommended for both filters. These
provide an optimal balance between small size, cost, reliabil-
ity and performance for cell phones and similar applications.
Table 2
lists suggested capacitors and suppliers.
TABLE 2. Suggested Capacitors and Their Suppliers
Model
Size (EIA)
2012 (0805)
2012 (0805)
3216 (1206)
Vendor
Taiyo-Yuden
TDK
TDK
LMK212BJ475MG
C2012X5R1A475K
C3216X5R1A106K
The DC bias characteristics of the capacitor must be consid-
ered when making the selection. If smaller case size such as
1608 (0603) is selected, the dc bias could reduce the cap
value by as much as 40%, in addition to the 20% tolerances
and 15% temperature coefficients. Request dc bias curves
from manufacturer when making selection. The device has
been designed to be stable with output capacitors as low as
3μF to account for capacitor tolerances. This value includes
dc bias reduction, manufacturing tolerances and temp coef-
ficients.
The input filter capacitor supplies AC current drawn by the
PFET switch of the LM3204 in the first part of each cycle and
reduces the voltage ripple imposed on the input power
source.A0.1μF capacitor is also recommended close to V
pin. The output filter capacitor absorbs the AC inductor cur-
rent, helps maintain a steady output voltage during transient
load changes and reduces output voltage ripple. These ca-
pacitors must be selected with sufficient capacitance and
sufficiently low ESR (Equivalent Series Resistance) to per-
form these functions. The ESR of the filter capacitors is
generally a major factor in voltage ripple.
MICRO SMD PACKAGE ASSEMBLY AND USE
Use of the Micro SMD package requires specialized board
layout, precision mounting and careful re-flow techniques, as
detailed in National Semiconductor Application Note 1112.
Refer to the section
Surface Mount Technology (SMD) As-
sembly Considerations
. For best results in assembly, align-
ment ordinals on the PC board should be used to facilitate
placement of the device. The pad style used with Micro SMD
package must be the NSMD (non-solder mask defined) type.
This means that the solder-mask opening is larger than the
pad size. This prevents a lip that otherwise forms if the
solder-mask and pad overlap, from holding the device off the
surface of the board and interfering with mounting. See
Application Note 1112 for specific instructions how to do this.
The 10-Bump package used for the LM3204 has 300 micron
solder balls and requires 10.82 mil pads for mounting on the
circuit board. The trace to each pad should enter the pad
with a 90 entry angle to prevent debris from being caught in
deep corners. Initially, the trace to each pad should be 6-7
mil wide, for a section approximately 6 mil long or longer, as
a thermal relief. Then each trace should neck up or down to
its optimal width. The important criterion is symmetry. This
ensures the solder bumps on the LM3204 re-flow evenly and
that the device solders level to the board. In particular,
special attention must be paid to the pads for bumps B3, C3
and D3. Because PGND and PV
IN
are typically connected to
large copper planes, inadequate thermal relief can result in
inadequate re-flow of these bumps.
The Micro SMD package is optimized for the smallest pos-
sible size in applications with red or infrared opaque cases.
Because the Micro SMD package lacks the plastic encapsu-
lation characteristic of larger devices, it is vulnerable to light.
Backside metallization and/or epoxy coating, along with
front-side shading by the printed circuit board, reduce this
sensitivity. However, the package has exposed die edges. In
particular, Micro SMD devices are sensitive to light, in the
red and infrared range, shining on the package’s exposed
die edges.
Do not use or power-up the LM3204 while subjecting it to
high intensity red or infrared light; otherwise degraded, un-
predictable or erratic operation may result. Examples of light
sources with high red or infrared content include the sun and
halogen lamps. Place the device in a case opaque to red or
infrared light.
L
www.national.com
14
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| LM3205SD-2 | 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3204TL/NOPB | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| LM3204TLEV | 功能描述:電源管理IC開發(fā)工具 LM3204 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM3204TLX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Miniature, Adjustable, Step-Down DC-DC Converter with Bypass Mode for RF Power Amplifiers |
| LM3204TLX/NOPB | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| LM3205 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers |
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