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参数资料
| 型号： | LTC3205EUF#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 12/16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
The efficiency of the LTC3205 depends upon the mode in
which it is operating. Recall that the LTC3205 operates as
a pass switch, connecting V IN to CPO until one of the LEDs
on the main or sub displays drops out. This feature
for a 2:3 fractional charge pump is approximately 1.5
times the load current. In an ideal 2:3 charge pump, the
power efficiency would be given by:
= ?
providestheoptimumefficiencyavailableforagiveninput
voltage and LED forward voltage. When it is operating as
a switch, the efficiency is approximated by:
η IDEAL ≡
P LED
P IN
V LED ? I LED
3
V IN ? I LED
2
V LED
1 . 5 V IN
= ? LED
η≡
P LED
P IN
V LED ? I LED V
V IN ? I IN V IN
Using the RED, GREEN and BLUE Pins with Higher
Currents
since the input current will be very close to the LED
current.
At moderate to high output power, the quiescent current
of the LTC3205 is negligible and the expression above is
valid. For example, with V IN = 3.9V, I OUT = 20mA ? 6 LEDs
and V LED equal to 3.6V, the measured efficiency is 92.2%,
which is very close to the theoretical 92.3% calculation.
Once an LED drops out, the LTC3205 switches into step-
up mode. Employing the fractional ratio 2:3 charge pump,
the LTC3205 provides more efficiency than would be
achieved with a voltage doubling charge pump.
In 2:3 boost mode, the efficiency is similar to that of a
linear regulator with an effective input voltage of 1.5 times
the actual input voltage. This is because the input current
The RED, GREEN and BLUE current source pins can be
used at higher current levels to provide features such as a
flash or camera light. Given that the output impedance of
the currrent source is approximately 3.3 ? when in satu-
ration, more compliance voltage will be necessary to
operate the device at higher LED currents. Figure 8 shows
the current source accuracy of the RED, GREEN and BLUE
pins as a function of the pin voltage for various high
current settings.
Programming the I MS or I RGB pins for more than 75 μ A
requires a higher supply voltage to support the extra
current. Figure 9 shows the minimum input supply voltage
required to support various levels of current on the I MS and
I RGB pins.
120
100
V IN = 3.6V
T A = 25 ° C
I RGB = 250 μ A
I RGB = 200 μ A
3.9
3.7
3.5
T A = 25 ° C
I MS
80
60
I RGB = 150 μ A
3.3
40
20
0
I RGB = 100 μ A
I RGB = 50 μ A
3.1
2.9
2.7
2.5
I RGB
0
0.2
0.4 0.6 0.8
1.0
25
50
75 100 125 175 200 225 250
LED PIN VOLTAGE (V)
3205 F08
Figure 8. Compliance Voltage Required to get Higher
LED Currents
I MS OR I RGB CURRENT ( μ A)
3205 F09
Figure 9. Input Supply Voltage Required to Support
Higher Currents
3205f
12
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相关代理商/技术参数 |
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| 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 |
| LTC3205XEUF#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 |
| LTC3206 | 制造商:LINER 制造商全称:Linear Technology 功能描述:I2C Multidisplay LED Controller |
| LTC3206EUF | 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 |
| LTC3206EUF#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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