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參數(shù)資料
| 型號： | MAX8901B |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package |
| 中文描述： | 效率最高的2至6只串聯(lián)WLED供電電源，2mm x 2mm TDFN封裝 |
| 文件頁數(shù)： | 11/15頁 |
| 文件大?。?/td> | 310K |
| 代理商： | MAX8901B |
M
Highest Efficiency Supply for 2 to 6
Series WLEDs in a 2mm x 2mm TDFN Package
______________________________________________________________________________________
11
Schottky Diode Selection
The high switching frequency of the MAX8901_
demands a high-speed rectification diode for optimum
efficiency. A Schottky diode is recommended due to its
fast recovery time and low forward voltage drop.
Ensure that the diode’s average and peak current
rating exceeds the average output current and peak
inductor current. In addition, the diode’s reverse
breakdown voltage must exceed V
OUT
. The RMS diode
current can be approximated from the following
equation:
Capacitor Selection
Ceramic capacitors with X5R, X7R, or better dielectric
are recommended for stable operation over the entire
operating temperature range. The exact values of input
(C1) and output (C2) capacitors are not critical (see
Figures 4 and 5). The typical value for the input
capacitor is 1μF, and the typical value for the output
capacitor is 0.1μF (MAX8901A) or 1μF (MAX8901B).
Higher value capacitors can reduce input and output
ripple, but at the expense of size and higher cost. The
compensation capacitor (C3) stabilizes the converter
and controls soft-start. The compensation capacitor is
typically chosen to be 0.022μF for most applications.
Current-Sense Resistor (MAX8901A Only)
The MAX8901A uses a sense resistor (R
CS
) connected
from CS to GND to program the maximum WLED cur-
rent for 100% PWM duty cycle. The MAX8901A regu-
lates V
CS
to 0.5V (typ) for 100% duty cycle. Calculate
R
CS
(in ohms) using the following equation:
where I
LED(MAX)
is the maximum WLED current in
milliamps. Maximum WLED current is programmed to
25mA using a 20
Ω
resistor.
PCB Layout
Due to fast switching waveforms and high-current
paths, careful attention is required when the PCB layout
is designed. Minimize trace lengths between the IC and
the inductor, the diode, the input capacitor, and the
output capacitor. For the MAX8901A, minimize the
trace length between the IC and R
CS
. Keep traces
short, direct, and wide. Keep noisy traces, such as the
LX node trace, away from CS. The input bypass
capacitor (C
IN
) should be placed as close as possible
to the IC. The ground connections of C
IN
and C
OUT
should be as close together as possible. PGND and
GND should be connected together at the input
capacitor ground terminal. Refer to the MAX8901 EV Kit
for an example layout.
R
CS
LED(MAX)
I
500
=
I
DIODE RMS
(
)
=
×
I
I
LED
PEAK
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX8901BETA+ | 制造商:Maxim Integrated Products 功能描述:HIGHEST EFFICIENCY SUPPLY FOR 2 TO 6 SERIES WLEDS IN A - Rail/Tube |
| MAX8901BETA+CAR | 功能描述:LED照明驅(qū)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(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| MAX8901BETA+T | 功能描述:LED照明驅(qū)動器 Supply for 2 to 6 Series WLEDs 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(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| MAX8901BETA+TCAR | 功能描述:LED照明驅(qū)動器 Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package 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(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| MAX8901BETA+TCH8 | 功能描述:LED照明驅(qū)動器 Supply for 2 to 6 Series WLEDs 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(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
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