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參數(shù)資料
| 型號(hào)： | MAX1553EVKIT |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | MAX1553 Evaluation Kit |
| 中文描述： | MAX1553評(píng)估板 |
| 文件頁(yè)數(shù)： | 6/11頁(yè) |
| 文件大?。?/td> | 347K |
| 代理商： | MAX1553EVKIT |
M
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
6
_______________________________________________________________________________________
Detailed Description
Control Scheme
The MAX1553/MAX1554 utilize a minimum off-time, cur-
rent-limited control scheme. If the voltage at FB drops
below the regulation threshold, the internal low-side
MOSFET turns on and the inductor current ramps up to
the current limit. Once the current-limit comparator
trips, the low-side MOSFET turns off for the minimum
off-time (250ns). After 250ns, if the voltage at FB is
above the regulation threshold, the low-side MOSFET
stays off. If the voltage at FB is below the regulation
point, the low-side MOSFET turns back on and the
cycle repeats. By using a regulation control scheme
that is not fixed frequency and that can skip pulses, the
MAX1553/MAX1554 operate with very high efficiency.
Soft-Start
Soft-start is provided on the MAX1553/MAX1554 to min-
imize inrush current. The soft-start time is set with an
external capacitor, C3 (Figures 1, 2, and 3). Use the fol-
lowing equation to solve for C3:
where t
SS
is the soft-start time. A value of 0.1μF pro-
vides a soft-start time of 20ms.
Shutdown
The MAX1553/MAX1554 feature a low-current shut-
down feature. When EN is low, the IC turns off, reduc-
ing its supply current to approximately 0.1μA. For
normal operation, drive EN high or connect to V
CC
.
Overvoltage Protection
The MAX1553/MAX1554 have an adjustable overvoltage-
protection circuit. When the voltage at OV reaches the
overvoltage threshold (1.25V typ), the protection circuitry
prevents the internal MOSFET from switching, allowing
the output voltage to decay.
The peak output voltage in an overvoltage-protection
event is set with a resistor-divider from the output con-
nected to OV (R2 and R3 in Figures 1, 2, and 3). Select
a value for R3 (10k
is recommended), then solve for
R2 using the following equation:
where V
OV
is the overvoltage threshold (1.25V typ), and
V
OUT(PEAK)
is the desired peak output voltage.
R
R
x
V
V
OUT PEAK
(
OV
2
3
1
=
)
C
x
tSS
3
2
10
5
=
Pin Description
PIN
1
2
3
NAME
GND
V
CC
EN
FUNCTION
Ground
Voltage-Supply Input. 2.7V to 5.5V. The IC is powered from V
CC
.
Enable Input. Drive high or connect to V
CC
to enable the IC. Drive EN low for shutdown.
4
BRT
Brightness-Control Input. Either an analog or PWM control signal can be used. The LED current can be
controlled over a 10 to 1 range. The PWM signal must be between 100Hz and 10kHz, and must have an
amplitude greater than 1.72V.
5
FB
Feedback Input. Connect to the cathode of the LED string and connect a resistor from FB to GND to set the
LED current.
6
SS
Soft-Start Timing-Control Input. Connect a capacitor from SS to GND to control soft-start timing. See the
Soft-
Start
section for information on selecting the soft-start capacitor. SS is pulled to ground with an internal 200
switch when EN is low.
7
OV
Overvoltage Sense. Connect to a resistor-divider from the anode of the LED string to set the overvoltage
threshold. See Figures 1, 2, and 3.
8
—
LX
EP
Inductor Connection. Connect to the inductor and diode. LX is high impedance when EN is low.
Exposed Pad. Connect to GND.
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| MAX1554ETA | 制造商:Maxim Integrated Products 功能描述:SMALLEST, HIGHEST-EFFICIENCY, 40V STEP-UP CON - Bulk 制造商:Rochester Electronics LLC 功能描述: |
| MAX1554ETA+ | 制造商:Maxim Integrated Products 功能描述:LED DRVR 10SEGMENT 3.15V TO 5.5V 8TDFN EP - Rail/Tube |
| MAX1554ETA+T | 功能描述:LED照明驅(qū)動(dòng)器 40V StepUp Converter for 2-10 White LEDs 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 |
| MAX1554ETA+TG069 | 制造商:Maxim Integrated Products 功能描述:LED DRVR 10SEGMENT 3.15V TO 5.5V 8TDFN EP - Tape and Reel |
| MAX1554ETA-T | 功能描述:LED照明驅(qū)動(dòng)器 40V StepUp Converter for 2-10 White LEDs 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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