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参数资料
| 型号： | YB1518ST25 |
| 厂商： | YOBON TECHNOLOGIES, INC. |
| 元件分类： | DC/DC变换器 |
| 英文描述： | Step-up DC-DC Converter White LED Driver |
| 中文描述： | 升压DC - DC转换器白光LED驱动器 |
| 文件页数： | 12/12页 |
| 文件大小： | 1582K |
| 代理商： | YB1518ST25 |
YB1518
Step-up DC-DC Converter White LED Driver
YB1518 MRev.1.2
www.yobon.com.tw
9
Functional Block
Operation
The YB1518 uses a constant frequency,
current mode control scheme to regulate
the output LED current. Its operation can
be understood by referring to the block
diagram in Figure 3. At the start of each
oscillator cycle, a voltage proportional to
the switch current is added to a ramp
output and the resulting sum is fed into the
positive terminal of the PWM comparator
(comparator-1). When this voltage exceeds
the level of the comparator negative input,
the peak current has been reached, and
the SR latch (in Control Logic) is reset and
turns off the power switch. The voltage at
the negative input of the comparator comes
from the output of the error amplifier. The
error amplifier sets the correct peak current
level to keep the output in regulation. If the
error amplifier’s output increases, more
current is delivered to the output; if it
decreases, less current is delivered.
Application Information
Soft Start and Current Limit
The internal soft start circuit minimizes the
inrush current during turning on YB1518.
The maximum switch current is limited to
about 450 mA by the chip.
LED Current and Dimming Control
The LED’s current is set by a resistor
connected at FB pin to GND using:
The maximum LED current set initially can
be reduced by pulse width modulating the
CTRL. A better approach is to adjust the
feedback voltage for dimming control.
Either a DC level signal or a filtered PWM
signal can be used to control the LED
current as illustrated in Figure 4 and Figure
Figure 3: YB1518 Block Diagram
LED
R
mV
I
100
=
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相关代理商/技术参数 |
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| YB1519 | 制造商:YOBON 制造商全称:YOBON 功能描述:High-Power White LED Driver |
| YB1520 | 制造商:YOBON 制造商全称:YOBON 功能描述:High Power Step-up DC-DC Converter, White LED Driver |
| YB1520ST25 | 制造商:YOBON 制造商全称:YOBON 功能描述:High Power Step-up DC-DC Converter, White LED Driver |
| YB1521 | 制造商:YOBON 制造商全称:YOBON 功能描述:High Power Step-Up DC-DC Converter & WLED Driver |
| YB1521ST25 | 制造商:YOBON 制造商全称:YOBON 功能描述:High Power Step-Up DC-DC Converter & WLED Driver |
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