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| 型号： | LT3755EMSE-2#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/26页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR HP CONS CURR 16-MSOP |
| 标准包装： | 2,500 |
| 恒定电流： | 是 |
| 恒定电压： | 是 |
| 拓扑： | 回扫，低端，PWM，SEPIC，降压（降压），升压（升压） |
| 输出数： | 1 |
| 内部驱动器： | 无 |
| 类型 - 主要： | 车载 |
| 类型 - 次要： | 白色 LED |
| 频率： | 100kHz ~ 1MHz |
| 电源电压： | 4.5 V ~ 40 V |
| 输出电压： | 75V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TFSOP（0.118"，3.00mm 宽）裸露焊盘 |
| 供应商设备封装： | 16-MSOP，裸露焊盘 |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 125°C |
LT3755/LT3755-1/LT3755-2
APPLICATIONS INFORMATION
C GATE = 3300pF
zeroandfullcurrenttoachieveapreciselyprogrammed
average current. To make PWM dimming more accurate,
the switch demand current is stored on the VC node dur-
ing the quiescent phase when PWM is low. This feature
minimizes recovery time when the PWM signal goes high.
To further improve the recovery time, a disconnect switch
may be used in the LED current path to prevent the ISP
node from discharging during the PWM signal low phase.
The minimum PWM on or off time is affected by choice
of operating frequency and external component selection.
The data sheet application titled “Buck Mode 500mA LED
Driver for 20kHz PWM Dimming” demonstrates regulated
current pulses as short as 1μs are achievable. The best
overall combination of PWM and analog dimming capabil-
ity is available if the minimum PWM pulse is at least six
switching cycles.
Programming the Switching Frequency
The RT frequency adjust pin allows the user to program
the switching frequency from 100kHz to 1MHz to optimize
efficiency/performance or external component size. Higher
frequency operation yields smaller component size but
increases switching losses and gate driving current, and
may not allow sufficiently high or low duty cycle operation.
Lower frequency operation gives better performance at the
cost of larger external component size. For an appropriate
R T resistor value see Table 1. An external resistor from the
RT pin to GND is required—do not leave this pin open.
Duty Cycle Considerations
Switching duty cycle is a key variable defining converter
operation, therefore, its limits must be considered when
programming the switching frequency for a particular
application. The fixed minimum on-time and minimum
off-time (see Figure 4) and the switching frequency define
the minimum and maximum duty cycle of the switch,
respectively. The following equations express the mini-
mum/maximum duty cycle:
Min Duty Cycle = (minimum on-time) ? switching
frequency
Max Duty Cycle = 1 – (minimum off-time) ? switching
frequency
When calculating the operating limits, the typical values
for on/off-time in the data sheet should be increased by
at least 60ns to allow margin for PWM control latitude,
GATE rise/fall times and SW node rise/fall times.
300
250
MINIMUM ON-TIME
200
MINIMUM OFF-TIME
150
100
50
Table 1. Switching Frequency vs R T Value
f OSC (kHz)
R T (kΩ)
0
–50 –25
0
25
50
75
100 125 150
1000
10.0
TEMPERATURE (°C)
37551 F04
900
800
700
600
500
400
300
200
100
11.8
13.0
15.4
17.8
21.0
26.7
35.7
53.6
100
Figure 4. Typical Minimum On and Off
Pulse Width vs Temperature
Thermal Considerations
The LT3755 is rated to a maximum input voltage of 40V.
Careful attention must be paid to the internal power dis-
sipation of the IC at higher input voltages to ensure that
a junction temperature of 125°C (150°C for H-Grade) is
not exceeded. This junction limit is especially important
37551fd
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3755EMSEPBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-Out Step Up/Down |
| LT3755EMSE-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:40VIN, 75VOUT LED Controller |
| LT3755EMSE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:40VIN, 75VOUT LED Controller |
| LT3755EUD#PBF | 功能描述:IC LED DRVR HP CONST CURR 16-QFN 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 |
| LT3755EUD#TRPBF | 功能描述:IC LED DRVR HP CONST CURR 16-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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