參數(shù)資料
型號(hào)： LM3402MRX
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 穩(wěn)壓器
英文描述： 0.5A Constant Current Buck Regulator for Driving High Power LEDs
中文描述： 0.94 A SWITCHING REGULATOR, PDSO8
封裝： PLASTIC, TSOP-8
文件頁(yè)數(shù)： 10/24頁(yè)
文件大?。?/td> 431K
代理商： LM3402MRX
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 cur-
rent through an array of LEDs. A voltage signal, V
SNS
, is
created as the LED current flows through the current setting
resistor, R
SNS
, to ground. V
SNS
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
falls
below V
REF
. The power MOSFET conducts for a controlled
on-time, t
ON
, set by an external resistor, R
, 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
is com-
plete the CS comparator compares V
SNS
and V
REF
again,
waiting to begin the next cycle.
www.national.com
10
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM3402MRX/NOPB 功能描述:開(kāi)關(guān)變換器、穩(wěn)壓器與控制器 RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開(kāi)關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel
LM3403 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Quad Operational Amplifiers
LM3403J 制造商:National Semiconductor 功能描述:3403 NSC'94 S4A1D
LM3403J/A+ 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Feedback Operational Amplifier
LM3403M 制造商:Texas Instruments 功能描述: 制造商:National Semiconductor 功能描述:3403 NSC'92 1LrgREEL
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