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| 型号： | LT3590ESC8#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 7/16页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WHITE BCKLGT SC-70-8 |
| 标准包装： | 2,500 |
| 拓扑： | PWM，降压（降压） |
| 输出数： | 1 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 650kHz ~ 1.05MHz |
| 电源电压： | 4.5 V ~ 55 V |
| 输出电压： | 55V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-VFSOP（0.492"，1.25mm 宽） |
| 供应商设备封装： | SC-70-8 |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
LT3590
OPERATION
The LT3590 uses a constant-frequency, current mode
control scheme to provide excellent line and load regula-
tion. Operation can be best understood by referring to the
Block Diagram.
At power-up, the bandgap reference, the start-up bias, and
the regulator are turned on. If CTRL is pulled higher than
150mV, the switching converter sub-blocks including the
oscillator, the PWM comparator and the error ampli?er
are also turned on. At the start of each oscillator cycle,
the power switch Q1 is turned on. Current ?ows through
the inductor and the switch to ground, ramping up as the
switch stays on. A voltage proportional to the switch cur-
rent is added to a stabilizing ramp and the resulting sum
is fed into the positive terminal of the PWM comparator.
When this voltage exceeds the level at the negative input of
the PWM comparator, the PWM logic turns off the power
switch. The level at the negative input of the PWM com-
parator is set by the error ampli?er EAMP, and is simply
an ampli?ed version of the difference between the V IN and
V LED voltage and the bandgap reference. In this manner,
the error ampli?er sets the correct peak current level in
inductor L1 to keep the output in regulation. The CTRL
pin is used to adjust the reference voltage.
The LT3590 enters into shutdown when CTRL is pulled
lower than 100mV.
Input Voltage Range
The minimum input voltage required to generate a particular
output voltage in an LT3590 application is limited by either
its 4.5V limit or by its maximum duty cycle. The duty cycle
is the fraction of time that the internal switch is on and is
determined by the input and output voltages:
The maximum input voltage is limited by the absolute
maximum V IN rating of 55V.
Pulse-Skipping
For LED strings with a low number of LEDs (1, 2, or 3),
the LT3590 can drive currents without pulse-skipping as
long as the voltage across the LED and sense resistor is
greater than roughly 15% of the input supply voltage. If
the LED voltage plus sense resistor is less than 15% of
the input supply, the device will begin skipping pulses.
This will result in some low frequency ripple, although
the LED current remains regulated on an average basis
down to zero.
Discontinuous Current Mode
The CTRL pin, in conjunction with the sense resistor,
can be used to program the LED current as discussed
under Applications Information. The LT3590 can drive a
10-LED string at 10mA LED current operating in continu-
ous conduction mode, using the recommended external
components shown in the front page application circuit
with the sense resistor equal to 10Ω. As current is further
reduced, the regulator enters discontinuous conduction
mode. The photo in Figure 2 details circuit operation driving
ten LEDs at 2mA load. During the discharge phase, the
inductor current reaches zero. After the inductor current
reaches zero, the SW pin exhibits ringing due to the LC
tank circuit formed by the inductor in combination with
the switch and the diode capacitance. This ringing is not
harmful; far less spectral energy is contained in the ringing
than in the switch transitions. The ringing can be damped
by application of a 3kΩ resistor across the inductor, al-
though this will degrade ef?ciency.
DC =
V LED + V D
V IN – V SW + V D
V SW
20V/DIV
Where V D is the forward voltage drop of the catch diode
(~0.8V) and V SW is the voltage drop of the internal switch
at maximum load (~0.5V). Given DC MAX = 0.9, this leads
to minimum input voltage of:
I L
10mA/DIV
V IN ( MIN ) =
( V LED + V D )
DC MAX
+ V SW ? V D
400ns/DIV
V IN = 48V
I LED = 2mA
10 WHITE LEDs
L = 470μH (MURATA)
3590 F02
Figure 2. Switching Waveforms
3590f
7
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3591 | 制造商:LINER 制造商全称:Linear Technology 功能描述:20mA LED Driver and OLED Driver with Integrated Schottky in 3mm x 2mm DFN |
| LT3591EDDB#PBF | 制造商:Linear Technology 功能描述:LED DRVR 10Segment 3.3V/5V/9V 8-Pin DFN EP 制造商:Linear Technology 功能描述:LED DRIVER BOOST PWM/ANALOGU 制造商:Linear Technology 功能描述:LED DRIVER, BOOST, PWM/ANALOGUE, 1MHZ, DFN-8; Topology:Boost (Step Up); No. of Outputs:1; Output Voltage:42V; Driver Case Style:DFN; Input Voltage Min:2.5V; Input Voltage Max:12V; Dimming Control Type:PWM / Analogue ;RoHS Compliant: Yes |
| LT3591EDDB#TRMPBF | 功能描述:IC LED DRIVER WHITE BCKLGT 8-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:60 系列:- 恒定电流:- 恒定电压:- 拓扑:线性（LDO），PWM，升压（升压） 输出数:8 内部驱动器:是 类型 - 主要:背光 类型 - 次要:RGB，白色 LED 频率:500kHz ~ 1.5MHz 电源电压:4.75 V ~ 26 V 输出电压:45V 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* 工作温度:-40°C ~ 85°C |
| LT3591EDDB#TRPBF | 功能描述:IC LED DRIVER WHITE BCKLGT 8-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:6,000 系列:- 恒定电流:- 恒定电压:- 拓扑:开路漏极，PWM 输出数:4 内部驱动器:是 类型 - 主要:LED 闪烁器 类型 - 次要:- 频率:400kHz 电源电压:2.3 V ~ 5.5 V 输出电压:- 安装类型:表面贴装 封装/外壳:8-VFDFN 裸露焊盘 供应商设备封装:8-HVSON 包装:带卷 (TR) 工作温度:-40°C ~ 85°C 其它名称:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
| LT3591EDDBTRMPBF | 制造商:Linear Technology 功能描述:LED Driver 10-Seg 3.3/5/9V DFN8EP |
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