- 您现在的位置：买卖IC网 > PDF目录20878 > LTC3205EUF#TR (Linear Technology)IC LED DRVR WT/RGB BCKLGT 24-QFN PDF资料下载
参数资料
| 型号： | LTC3205EUF#TR |
| 厂商： | Linear Technology |
| 文件页数： | 7/16页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WT/RGB BCKLGT 24-QFN |
| 标准包装： | 2,500 |
| 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： | 带卷 (TR) |
| 工作温度： | -40°C ~ 85°C |
LTC3205
OPERATIO
Power Management
To optimize efficiency, the power management section of
the LTC3205 provides two methods of supplying power to
the CPO pin: 1:1 direct connect mode or 2:3 boost mode.
When either the main or sub displays of the LTC3205 are
enabled, the power management system connects the CPO
pin directly to V IN with a low impedance switch. If the voltage
supplied at V IN is high enough to power all of the LEDs with
the programmed current, the system will remain in this
However, for a given R OL , the amount of current available
will be directly proportional to the advantage voltage 1.5V IN
– V CPO . Consider the example of driving white LEDs from
a 3.1V supply. If the LED forward voltage is 3.8V and the
current sources require 100mV, the advantage voltage is
3.1V ? 1.5V – 3.8V – 0.1V or 750mV. Notice that if the input
voltage is raised to 3.2V, the advantage voltage jumps to
900mV—a 20% improvement in available strength.
From Figure 1, the available current is given by:
“direct connect” mode providing maximum efficiency.
Internal circuits monitor all MAIN and SUB current sources
for the onset of “dropout,” the point at which the current
I OUT =
1.5 V IN – V CPO
R OL
sources can no longer supply programmed current. As the
battery voltage falls, the LED with the largest forward volt-
age will reach the “drop out” threshold first. When any of
Typical values of R OL as a function of temperature are
shown in Figure 2.
the four main or two sub display LEDs reach the dropout
threshold, the LTC3205 will switch to boost mode and au-
R OL
+
–
tomatically soft-start the 2:3 boost charge pump. The con-
stant frequency charge pump is designed to minimize the
+
1.5V IN
CPO
–
amount of noise generated at the V IN supply.
The 2:3 step-up charge pump uses a patented constant
frequency architecture to combine the best efficiency with
3205 F01
Figure 1. Equivalent Open-Loop Circuit
the maximum available power at the lowest noise level.
If the red, green or blue LEDs are programmed to be on at
any duty cycle, the charge pump runs continuously.
Soft-Start
To prevent excessive inrush current and supply droop
when switching into step-up mode, the LTC3205 employs
a soft-start feature on its charge pump. The current
available to the CPO pin is increased linearly over a period
3.2
3.0
2.8
2.6
2.4
2.2
V IN = 3V
V CPO = 4.2V
C IN = C CPO = C FLY1 = C FLY2 = 1 μ F
of 1.2ms.
2.0
–40
–15
10 35
60
85
TEMPERATURE ( ° C)
Charge Pump Strength
When the LTC3205 operates in 2:3 boost mode, the
charge pump can be modeled as a Thevenin-equivalent
circuit to determine the amount of current available from
the effective input voltage, 1.5V IN and the effective open-
loop output resistance, R OL (Figure 1).
R OL is dependent on a number of factors including the
switching term, 1/(2f OSC ? C FLY ), internal switch resis-
tances and the nonoverlap period of the switching circuit.
3205 F02
Figure 2. Typical R OL vs Temperature
Zero Shutdown Current
Although the LTC3205 is designed to have very low shut-
down current, it will draw about 400nA on V IN when in
shutdown. For applications that require zero shutdown
current, the DV CC pin can be grounded. This will reduce the
V IN current to very near zero. Internal logic ensures that the
3205f
7
相关PDF资料 |
PDF描述 |
|---|---|
| REC3-0515SRW/H6/A/SMD/CTRL-R | CONV DC/DC 3W 4.5-9VIN 15VOUT |
| EEC15DRYS | CONN EDGECARD 30POS DIP .100 SLD |
| REC5-4809SRWZ/H6/A/M | CONV DC/DC 5W 18-72VIN 09VOUT |
| P51-75-A-H-M12-4.5OVP-000-000 | SENSOR 75PSI M12-1.5 6G .5-4.5V |
| P51-75-S-F-MD-4.5V-000-000 | SENSOR 75PSI 1/4-18NPT .5-4.5V |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
发布紧急采购，3分钟左右您将得到回复。