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LTC3201
APPLICATIO S I FOR ATIO
Operation (Refer to Simplified Block Diagram)
The LTC3201 is a switched capacitor boost charge pump
especially designed to drive white LEDs in backlighting
applications. The LTC3201’s internal regulation loop
maintains constant LED output current by monitoring the
voltage at the FB pin. The device has a novel internal filter
that, along with an external 0.22 μ F capacitor, significantly
reduces input current ripple. An internal 7-state DAC
allows the user to lower the regulation voltage at the FB
pin, thus lowering the LED current. To regulate the output
current, the user places a sense resistor between FB and
GND. The white LED is then placed between V OUT and FB.
The value at the FB pin is then compared to the output of
the DAC. The charge pump output voltage is then changed
to equalize the DAC output and the FB pin. The value of the
sense resistor determines the maximum value of the
output current.
When the charge pump is enabled, a two-phase
nonoverlapping clock activates the charge pump switches.
The flying capacitor is charged to V IN on phase one of the
clock. On phase two of the clock, it is stacked in series with
V IN and connected to V OUT . This sequence of charging and
discharging the flying capacitor continues at a free run-
ning frequency of 1.8MHz (typ) until the FB pin voltage
reaches the value of the DAC.
In shutdown mode all circuitry is turned off and the
LTC3201 draws only leakage current (<1 μ A) from the V IN
supply. Furthermore, V OUT is disconnected from V IN . The
LTC3201 is in shutdown when a logic low is applied to all
three D0:D2 pins. Note that if V OUT floats to >1.5V,
shutdown current will increase to 10 μ A max. In normal
operation, the quiescent supply current of the LTC3201
will be slightly higher if any of the D0:D2 pins is driven high
can go down to zero during this time. At the full load of
100mA at the output, this means that the input could
potentially go from 200mA down to 0mA during the
nonoverlap time. The LTC3201 mitigates this problem by
minimizing the nonoverlap time, using a high (1.8MHz)
frequency clock, and employing a novel noise FILTER
network. The noise filter consists of internal circuitry plus
external capacitors at the FILTER and V IN pins. The filter
capacitor serves to cancel the higher frequency compo-
nents of the noise, while the V IN capacitor cancels out the
lower frequency components. The recommended values
are 0.22 μ F for the FILTER capacitor and 1 μ F for the V IN
capacitor. Note that these capacitors must be of the highest
possible resonant frequencies. See Layout Considerations.
3-Bit DAC for Output Current Control
Digital pins D0, D1, D2 are used to control the output
current level. D0 = D1 = D2 = V IN allows the user to program
an output LED current that is equal to 0.63V/R SENSE , where
R SENSE is the resistor connected to any single LED and
connected between FB and ground. Due to the finite
transconductance of the regulation loop, for a given diode
setting, the voltage at the FB Pin will decrease as output
current increases. All LEDs subsequently connected in
parallel should then have similar currents. The mismatch-
ing of the LED V F and the mismatching of the sense
resistors will cause a differential current error between
LEDs connected to the same output. Once the sense
resistor is selected, the user can then control the voltage
applied across that resistor by changing the digital values
at D0:D2. This in turn controls the current into the LED.
Note that there are only 7 available current states. The 8th
is reserved to shutdown. This is the all 0s code. Refer to
Table below.
with a signal that is below V IN than if it is driven all the way
to V IN . Since the D0:D2 pins are high impedance CMOS
inputs, they should never be allowed to float.
Input Current Ripple
The LTC3201 is designed to minimize the current ripple at
V IN . Typical charge pump boost converters draw large
amounts of current from V IN during both phase 1 and
phase 2 of the clocking. If there is a large nonoverlap time
between the two phases, the current being drawn from V IN
D0
HIGH
HIGH
HIGH
HIGH
LOW
LOW
LOW
LOW
D1
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
LOW
D2
HIGH
LOW
HIGH
LOW
HIGH
LOW
HIGH
LOW
FB
0.63V
0.54V
0.45V
0.36V
0.27V
0.18V
0.09V
Shutdown
3201f
5
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相关代理商/技术参数
LTC3202 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise, High Efficiency Charge Pump for White LEDs
LTC3202EDD 功能描述:IC LED DRIVR WHITE BCKLGT 10-DFN RoHS:否 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 恒定电流:- 恒定电压:- 拓扑:升压（升压），切换式电容器（充电泵） 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:625kHz ~ 875kHz 电源电压:2.7 V ~ 5.3 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-µMAX 包装:带卷 (TR) 工作温度:-40°C ~ 85°C
LTC3202EDD#PBF 功能描述:IC LED DRIVR WHITE BCKLGT 10-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
LTC3202EDD#TR 功能描述:IC LED DRIVR WHITE BCKLGT 10-DFN 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
LTC3202EDD#TRPBF 功能描述:IC LED DRIVR WHITE BCKLGT 10-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
LTC3202EMS 功能描述:IC LED DRVR WHITE BCKLGT 10-MSOP 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
LTC3202EMS#PBF 功能描述:IC LED DRVR WHITE BCKLGT 10-MSOP 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
LTC3202EMS#TR 功能描述:IC LED DRVR WHITE BCKLGT 10-MSOP 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