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參數資料
| 型號： | LM3402 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 0.5A Constant Current Buck Regulator for Driving High Power LEDs |
| 中文描述： | 0.5A的恒流降壓穩(wěn)壓器用于驅動高功率LED |
| 文件頁數： | 9/22頁 |
| 文件大?。?/td> | 840K |
| 代理商： | LM3402 |
Block Diagram
20192103
Application Information
THEORY OF OPERATION
The LM3402 and LM3402HV are buck regulators with a wide
input voltage range, low voltage reference, and a fast output
enable/disable function. These features combine to make
them ideal for use as a constant current source for LEDs with
forward currents as high as 500 mA. The controlled on-time
(COT) architecture is a combination of hysteretic mode con-
trol and a one-shot on-timer that varies inversely with input
voltage. Hysteretic operation eliminates the need for small-
signal control loop compensation. When the converter runs
in continuous conduction mode (CCM) the controlled on-time
maintains a constant switching frequency over the range of
input voltage. Fast transient response, PWM dimming, a low
power shutdown mode, and simple output overvoltage pro-
tection round out the functions of the LM3402/02HV.
CONTROLLED ON-TIME OVERVIEW
Figure 1 shows the feedback system used to control the
current through an array of LEDs. A voltage signal, V
, is
created as the LED current flows through the current setting
resistor, R
, to ground. V
is fed back to the CS pin,
where it is compared against a 200 mV reference, V
REF
. The
on-comparator turns on the power MOSFET when V
SNS
falls
below V
REF
. The power MOSFET conducts for a controlled
on-time, t
ON
, set by an external resistor, R
ON
, and by the
input voltage, V
IN
. On-time is governed by the following
equation:
At the conclusion of t
ON
the power MOSFET turns off for a
minimum off-time, t
, of 300 ns. Once t
OFF-MIN
is
complete the CS comparator compares V
SNS
REF
again, waiting to begin the next cycle.
L
www.national.com
9
相關PDF資料 |
PDF描述 |
|---|---|
| LM3402HV | 0.5A Constant Current Buck Regulator for Driving High Power LEDs |
| LM3402HVMM | 0.5A Constant Current Buck Regulator for Driving High Power LEDs |
| LM3402HVMMX | 0.5A Constant Current Buck Regulator for Driving High Power LEDs |
| LM3402MM | 0.5A Constant Current Buck Regulator for Driving High Power LEDs |
| LM3402MMX | 0.5A Constant Current Buck Regulator for Driving High Power LEDs |
相關代理商/技術參數 |
參數描述 |
|---|---|
| LM3402_07 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:0.5A Constant Current Buck Regulator for Driving High Power LEDs |
| LM3402_08 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:0.5A Constant Current Buck Regulator for Driving High Power LEDs |
| LM3402_1 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:LM3402/LM3404 Fast Dimming and True Constant LED Current Evaluation Board |
| LM3402EVAL | 功能描述:BOARD EVALUATION FOR LM3402 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - LED 驅動器 系列:PowerWise® 標準包裝:1 系列:PowerWise® 電流 - 輸出 / 通道:20mA 輸出及類型:1，非隔離 輸出電壓:17V 特點:可調光 輸入電壓:2.7 ~ 5.5 V 已供物品:板 已用 IC / 零件:LM3508 相關產品:LM3508TLX-ND - IC LED DRVR WHT BCKLGT 9USMDLM3508TLDKR-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLCT-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLTR-ND - IC LED DRVR WHT BCKLGT 9MICROSMD |
| LM3402EVAL | 制造商:Texas Instruments 功能描述:EVAL BOARD |
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