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參數(shù)資料
| 型號： | LM3500TLX-21 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 顯示驅動器 |
| 英文描述： | Synchronous Step-up DC/DC Converter for White LED |
| 中文描述： | LED DISPLAY DRIVER, BGA8 |
| 封裝： | MICRO, SMD-8 |
| 文件頁數(shù)： | 14/18頁 |
| 文件大小： | 1072K |
| 代理商： | LM3500TLX-21 |
Application Information
(Continued)
Typical Peak Inductor Currents (mA)
V
IN
(V)
# LEDs
(in
series)
LED Current
30
mA
134
190
244
319
116
168
212
288
96
148
186
263
15
mA
82
118
142
191
76
110
132
183
64
102
122
179
20
mA
100
138
174
232
90
126
158
216
76
116
146
206
40
mA
160
244
322
413
136
210
270
365
116
180
232
324
50
mA
204
294
X
X
172
250
320
446
142
210
272
388
60
mA
234
352
X
X
198
290
X
X
162
246
318
456
2.7
2
3
4
5
2
3
4
5
2
3
4
5
3.3
4.2
C
IN
= C
OUT
= 1 μF
L = 22 μH, 160 m
DCR max. Coilcraft DT1608C-223
2 and 3 LED applications: LM3500-16 or LM3500-21; LED V
F
= 3.77V at
20mA; T
A
= 25C
4 LED applications: LM3500-16 or LM3500-21; LED V
F
= 3.41V at 20mA; T
A
= 25C
5 LED applications: LM3500-21 only; LED V
F
= 3.28V at 20mA; T
A
= 25C
The typical cycle-by-cycle peak inductor current can be cal-
culated from the following equation:
where I
is the total load current, F
is the switching
frequency, L is the inductance and
η
is the converter effi-
ciency of the total driven load. A good typical number to use
for
η
is 0.8. The value of
η
can vary with load and duty cycle.
The average inductor current, which is also the average V
SW
pin current, is given by the following equation:
The maximum output current capability of the LM3500 can
be estimated with the following equation:
where I
is the current limit. Some recommended inductors
include but are not limited to:
Coilcraft DT1608C series
Coilcraft DO1608C series
TDK VLP4612 series
TDK VLP5610 series
TDK VLF4012A series
CAPACITOR SELECTION
Choose low ESR ceramic capacitors for the output to mini-
mize output voltage ripple. Multilayer X7R or X5R type ce-
ramic capacitors are the best choice. For most applications,
a 1μF ceramic output capacitor is sufficient.
Local bypassing for the input is needed on the LM3500.
Multilayer X7R or X5R ceramic capacitors with low ESR are
a good choice for this as well. A 1μF ceramic capacitor is
sufficient for most applications. However, for some applica-
tions at least a 4.7μF ceramic capacitor may be required for
proper startup of the LM3500. Using capacitors with low
ESR decreases input voltage ripple. For additional bypass-
ing, a 100nF ceramic capacitor can be used to shunt high
frequency ripple on the input. Some recommended capaci-
tors include but are not limited to:
TDK C2012X7R1C105K
Taiyo-Yuden EMK212BJ105 G
LAYOUT CONSIDERATIONS
The input bypass capacitor C
, as shown in
Figure 1
, must
be placed close to the device and connect between the V
IN
and GND pins. This will reduce copper trace resistance
which effects the input voltage ripple of the IC. For additional
input voltage filtering, a 100nF bypass capacitor can be
placed in parallel with C
to shunt any high frequency noise
to ground. The output capacitor, C
OUT
, should also be placed
close to the LM3500 and connected directly between the
V
OUT
and GND pins. Any copper trace connections for the
C
OUT
capacitor can increase the series resistance, which
directly effects output voltage ripple and efficiency. The cur-
rent setting resistor, R
LED
, should be kept close to the FB pin
to minimize copper trace connections that can inject noise
into the system. The ground connection for the current set-
ting resistor should connect directly to the GND pin. The
AGND pin should connect directly to the GND pin. Not
connecting the AGND pin directly, as close to the chip as
possible, may affect the performance of the LM3500 and
limit its current driving capability. Trace connections made to
the inductor should be minimized to reduce power dissipa-
tion, EMI radiation and increase overall efficiency. It is good
practice to keep the V
routing away from sensitive pins
such as the FB pin. Failure to do so may inject noise into the
FB pin and affect the regulation of the device. See
Figure 2
and
Figure 3
for an example of a good layout as used for the
LM3500 evaluation board.
L
www.national.com
14
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3500TLX-21/NOPB | 功能描述:LED照明驅動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:SO-16N |
| LM3501 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Synchronous Step-up DC/DC Converter for White LED Applications |
| LM3501TL-16 | 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Up 2.7V to 7V 8-Pin uSMD T/R 制造商:Texas Instruments 功能描述:IC, WHITE LED DRIVER, POWERWISE 制造商:Texas Instruments 功能描述:Display Driver,4LED,LM3501TL-16 |
| LM3501TL-16/NOPB | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| LM3501TL-16EV | 功能描述:電源管理IC開發(fā)工具 LM3501TL-16 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)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 |
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