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參數資料
| 型號： | MX841BE |
| 廠商： | IXYS CORP |
| 元件分類： | 穩(wěn)壓器 |
| 中文描述： | 2 A SWITCHED CAPACITOR REGULATOR, 1300 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | ROHS COMPLIANT, MS-012-AA, SOIC-8 |
| 文件頁數： | 4/6頁 |
| 文件大?。?/td> | 208K |
| 代理商： | MX841BE |
MX841
4
10/04/07
MX841
IXYS
Functional Description
The MX841 is specifically designed to be
operated from a single cell battery source. The
step-up voltage necessary for the constant
current source to drive up to 5 white LED’s in
series, or multiple strings of white LED’s, is
achieved with minimal external components. (See
Application Schematics on pages 1&4).
Setting the LED Current
The regulated output current is determined by the
selection of the sense Resistor connected from
the ISENSE input to ground, and the maximum user
defined voltage of the CTRL input. The desired
output current, (typically 15mA to 20mA for white
LED’s), is derived using the following formula for
the RSENSE value: RSENSE = (VCTRL X 1/13) / ILED.
Current Regulation / Light Intensity Control
The
ISENSE
voltage
is
fed
into
an
ErrorAmp/Comparator. The user defined Control
Voltage applied at the CTRL input is scaled by a
gain factor of 1/13 and compared to the ISENSE
voltage. If the scaled control voltage is greater
than the ISENSE voltage, the 1.0MHz oscillator
signal driving the N-Channel MOSFET will be
enabled. Once the ISENSE voltage reaches the
scaled CTRL voltage the oscillator signal is
modulated
on
and
off
by
the
ErrorAmp/Comparator to maintain the desired
regulated output current.
Light intensity is controlled by reducing the
voltage at the CTRL input. As the CTRL input
voltage is reduced below the user defined
maximum value, the oscillator signal driving the
N-Channel MOSFET is interrupted by the
ErrorAmp/Comparator. The pulse skip modulating
of the N-Channel MOSFET causes a reduction in
the regulated current equal to the ratio of the
reduced CTRL voltage to the maximum CTRL
voltage.
Sleep Mode
The MX841 goes into sleep mode when the VCTRL
input is less than 100mV. All circuits except VCTRL
detection are shutdown and the supply current
falls to 6uA. Once the VCTRL input rises above
260mV the MX841 resumes normal operation.
Over Voltage Detection
The MX841 will go into a shutdown state to avoid
an over voltage condition if the current path
between the SW output and the RSENSE input is
interrupted. A voltage reference and comparator
circuit evaluates the voltage potential at the OVD
input and shuts down the oscillator and N-
Channel MOSFET if an over voltage condition is
detected. Normal operation is resumed once the
OVD input voltage falls below the reference
voltage, (20V typical).
Circuit Application Driving 15 White LED’s
MX841
CTRL
Vbattery 3.0V - 5.0V
VD
D
SW
OVD
Isense
CTL/SLEEP
Rsense
Vboost
1N5817
V
F=0.3V
6.8uH
I
pk=1.7A
20K Ohms
22uF 35V
0.1uF in Parallel
5 Ohms
22uF 35V
0.1uF in Parallel
26K Ohms @ 3.0V
57K Ohms @ 5.0V
(Dimming Control)
SW
Analog
GND
Switch
GND
2
14
6
8
5
7
3
Drawing No. 17023
www.claremicronix.com
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相關代理商/技術參數 |
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|---|---|
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| MX844R | 功能描述:板上安裝溫度傳感器 12-Bit Power & Temp Sensor QFN-28 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| MX844RTR | 功能描述:板上安裝溫度傳感器 12-Bit Power & Temp Sensor QFN-28 on T&R RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
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