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参数资料
| 型号： | MAX1848EKA |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | White LED Step-Up Converter in SOT23 |
| 中文描述： | 0.85 A SWITCHING REGULATOR, 1600 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | SOT-23, 8 PIN |
| 文件页数： | 7/9页 |
| 文件大小： | 323K |
| 代理商： | MAX1848EKA |
The output current and the number of LEDs in each leg
affect the capacitance of C
COMP
. Table 1 shows the
minimum C
COMP
values needed to stabilize the con-
verter in worst-case conditions. If further stability analy-
sis is required, note that the error amplifier has 50μA/V
transconductance.
Inductor Selection
The value of the inductor depends on the maximum
output current to the LEDs. See Table 1 for inductance
values and peak current ratings for the inductor.
Schottky Diode Selection
The MAX1848
’
s high-switching frequency demands a
high-speed rectification diode. A Schottky diode is
required due to their fast recovery time and low for-
ward-voltage drop. Ensure that the diode
’
s average
and peak current rating exceed the average output cur-
rent and peak inductor current, respectively. In addi-
tion, the diode
’
s reverse breakdown voltage must
exceed V
OUT
.
Applications Information
Connecting Four or Six LEDs
The MAX1848 can drive one, two, or three legs of LEDs
(Figure 2) as long as the total number of LEDs does not
exceed six. Each leg must contain the same number of
LEDs and the same sense-resistor value. Adding the
second or third leg does not affect the sense-resistor
value (see the
Adjusting LED Current
section).
Three legs of two LEDs is more efficient than two legs
of three LEDs (see Efficiency Graphs in the
Typical
Operating Characteristics
); however, a third sense
resistor is needed. Multiple legs can have slight current
mismatches due to component tolerances.
PC Board Layout
Due to fast-switching waveforms and high-current
paths, careful PC board layout is required. Protoboards
and wire-wrap boards should not be used for evalua-
tion. An evaluation kit (MAX1848EV kit) is available to
aid design.
When laying out a board, minimize trace lengths
between the IC and R
SENSE
, the inductor, the diode,
the input capacitor, and the output capacitor. Keep
traces short, direct, and wide. Keep noisy traces, such
as the inductor's traces, away from CS. V+
’
s bypass
capacitor (C
IN
) should be placed as close to the IC as
possible. PGND and GND should be connected in only
one place as close to the IC as possible. The ground
connections of C
IN
and C
OUT
should be as close
together as possible. The traces from V+ to the induc-
tor and from the Schottky diode to the LEDs may
be longer.
Refer to the MAX1848 EV kit for an example of proper
layout.
Chip Information
TRANSISTOR COUNT: 1290
I
I
I
DIODE(RMS)
OUT
PEAK
×
M
White LED Step-Up Converter in SOT23
_______________________________________________________________________________________
7
INDUCTOR
L (μH)
I
LED
(mA)
NO. OF
LEDs
C
COMP
(μF)
I
PEAK
( m A
3
2
3
2
3
2
3
2
0.220
0.100
0.150
0.068
0.100
0.047
0.068
0.01
12
56
80
20
33
130
40
15
260
60
10
375
Table 1. Component Selection
V+
CTRL
COMP
LX
OUT
PGND
GND
CS
2.6V to 5.5V
LOGIC
OR DAC
3.3
μ
F
0.01
μ
F
10
μ
H
1
μ
F
D1
MAX1848
30
R
SENSE
25
Figure 2. Six LEDs in 3 x 2 Configuration
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1848EKA-T | 功能描述:LED照明驱动器 White LED Step-Up RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX1848ETA | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY, UNIFORM-BRIGHTNESS, WHITE LE - Rail/Tube |
| MAX1848ETA+ | 制造商:Maxim Integrated Products 功能描述:LED DRVR 3SEGMENT 2.6V TO 5.5V 8PIN SOT-23 - Rail/Tube |
| MAX1848ETA+T | 功能描述:LED照明驱动器 White LED Step-Up RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MAX1848ETA-T | 功能描述:LED照明驱动器 White LED Step-Up RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
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