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参数资料
| 型号： | LTC3205EUF |
| 厂商： | Linear Technology |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WT/RGB BCKLGT 24-QFN |
| 标准包装： | 91 |
| 拓扑： | PWM，降压（降压），升压（升压），切换式电容器（充电泵） |
| 输出数： | 9 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 背光 |
| 类型 - 次要： | RGB，白色 LED |
| 频率： | 600kHz ~ 1.1MHz |
| 电源电压： | 2.8 V ~ 4.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 供应商设备封装： | 24-QFN 裸露焊盘（4x4） |
| 包装： | 管件 |
| 工作温度： | -40°C ~ 85°C |
LTC3205
APPLICATIO S I FOR ATIO
lose considerable capacitance over that range. Z5U and Y5V
capacitors may also have a very strong voltage coefficient
causing them to lose 60% or more of their capacitance when
the rated voltage is applied. Therefore, when comparing dif-
ferent capacitors, it is often more appropriate to compare
the amount of achievable capacitance for a given case size
rather than comparing the specified capacitance value. For
example, over rated voltage and temperature conditions,
a 1 μ F, 10V, Y5V ceramic capacitor in a 0603 case may not
provide any more capacitance than a 0.22 μ F, 10V, X7R
available in the same 0603 case. The capacitor
manufacturer’s data sheet should be consulted to determine
what value of capacitor is needed to ensure minimum
capacitances at all temperatures and voltages.
Table 4 shows a list of ceramic capacitor manufacturers
and how to contact them:
Table 4. Recommended Capacitor Vendors
charge pump will typically be weaker than the theoretical
limit due to additional switch resistance, however for very
light load applications, the above expression can be used
as a guideline in determining a starting capacitor value.
Layout Considerations and Noise
Due to its high switching frequency and the transient
currents produced by the LTC3205, careful board layout is
necessary. A true ground plane and short connections to
all capacitors will improve performance and ensure proper
regulation under all conditions. Figure 7 shows the recom-
mended layout configuration.
The flying capacitor pins C1 + , C2 + , C1 – and C2 – will have
very high edge rate waveforms. The large dv/dt on these pins
can couple energy capacitively to adjacent printed circuit
board runs. Magnetic fields can also be generated if the
flying capacitors are not close to the LTC3205 (i.e., the loop
AVX
Kemet
Murata
Taiyo Yuden
Vishay
www.avxcorp.com
www.kemet.com
www.murata.com
www.t-yuden.com
www.vishay.com
area is large). To decouple capacitive energy transfer, a
Faraday shield may be used. This is a grounded PC trace
between the sensitive node and the LTC3205 pins. For a high
quality AC ground, it should be returned to a solid ground
plane that extends all the way to the LTC3205
For very light load applications, the flying capacitors may
be reduced to save space or cost. The theoretical mini-
mum output resistance of a 2:3 fractional charge pump is
given by:
Power Efficiency
To calculate the power efficiency ( η ) of a white LED driver
chip, the LED power should be compared to the input
power. The difference between these two number repre-
=
R OL ( MIN ) ≡
1 . 5 V IN – V OUT 1
I OUT 2 f OSC C FLY
sents lost power whether it is in the charge pump or the
current sources. Stated mathematically, the power effi-
ciency is given by:
where f OSC is the switching frequency (800kHz typ) and
C FLY is the value of the flying capacitors. Note that the
PIN 1
η≡
P LED
P IN
GND
V IN
CPO
3205 F07
Figure 7. Optimum Single Layer PCB Layout
3205f
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3205EUF#PBF | 功能描述:IC LED DRVR WT/RGB BCKLGT 24-QFN 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 |
| LTC3205EUF#TR | 功能描述:IC LED DRVR WT/RGB BCKLGT 24-QFN RoHS:否 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 |
| LTC3205EUF#TRPBF | 功能描述:IC LED DRVR WT/RGB BCKLGT 24-QFN 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 |
| LTC3205EUFPBF | 制造商:Linear Technology 功能描述:Multidisplay LED Controller,LTC3205 |
| LTC3205XEUF#PBF | 功能描述:IC LED DRVR WT/RGB BCKLGT 24-QFN 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 |
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