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| 型号： | LTC3219EUD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/20页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVR QVGA DISPLAY 20-QFN |
| 标准包装： | 121 |
| 拓扑： | 开路漏极，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： | LED 闪烁器 |
| 频率： | 650kHz ~ 1.05MHz |
| 电源电压： | 2.9 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-WFQFN 裸露焊盘 |
| 供应商设备封装： | 20-QFN 裸露焊盘（3x3） |
| 包装： | 管件 |
| 工作温度： | -40°C ~ 85°C |
| 产品目录页面： | 1340 (CN2011-ZH PDF) |
LTC3219
APPLICATIONS INFORMATION
Power Ef?ciency
To calculate the power ef?ciency ( η ) of an LED driver chip,
the LED power should be compared to the input power.
The difference between these two numbers represents
lost power whether it is in the charge pump or the cur-
rent sources. Stated mathematically, the power ef?ciency
In 1.5x boost mode, the ef?ciency 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
for a 1.5x charge pump is approximately 1.5 times the
load current. In an ideal 1.5x charge pump, the power
ef?ciency would be given by:
η=
P LED V LED LED
V LED
η IDEAL =
= =
P IN V BAT LED 1.. 5 ? V BAT
is given by:
P LED
P IN
(4)
? I
? 1 . 5 ? I
Similarly, in 2x boost mode, the ef?ciency is similar to
P LED V LED LED
V LED
η IDEAL =
= =
P IN V BAT LED
2 ? V B AT
Theef?ciencyoftheLTC3219dependsuponthemodein
which it is operating. Recall that the LTC3219 operates
as a pass switch, connecting V BAT to CPO, until dropout
is detected at the I LED pin. This feature provides the op-
timum ef?ciency available for a given input voltage and
LED forward voltage. When it is operating as a switch, the
ef?ciency is approximated by:
that of a linear regulator with an effective input voltage
of 2 times the actual input voltage. In an ideal 2x charge
pump, the power ef?ciency would be given by:
? I
? 2 ? I
Thermal Management
V LED LED
= = LED
V BAT BAT
V BAT
η=
P LED
P IN
? I V
? I
(5)
For higher input voltages and maximum output current,
there can be substantial power dissipation in the LTC3219.
since the input current will be very close to the sum of
the LED currents.
At moderate to high output power, the quiescent current
of the LTC3219 is negligible and the expression above is
valid.
Once dropout is detected at any LED pin, the LTC3219
enables the charge pump in 1.5x mode.
If the junction temperature increases above approximately
150°C the thermal shutdown circuitry will automatically
deactivate the output current sources and charge pump.
To reduce maximum junction temperature, a good thermal
connection to the PC board is recommended. Connecting
the Exposed Pad to a ground plane and maintaining a solid
ground plane under the device will reduce the thermal
resistance of the package and PC board considerably.
3219fa
17
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| LTC3452EUF#TRPBF | IC LED DRIVER PHOTO FLASH 20-QFN |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3219EUD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:250mA Universal Nine Channel LED Driver |
| LTC3220 | 制造商:LINER 制造商全称:Linear Technology 功能描述:360mA Universal 18-Channel LED Driver |
| LTC3220_1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:360mA Universal 18-Channel LED Driver |
| LTC3220-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:360mA Universal 18-Channel LED Driver |
| LTC3220EPF#PBF | 功能描述:IC LED DRVR QVGA DISPLAY 28UTQFN 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 |
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