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| 型号： | LT1937ES5#TRM |
| 厂商： | Linear Technology |
| 文件页数： | 7/12页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVR WHITE BCKLGT TSOT-5 |
| 标准包装： | 1 |
| 恒定电流： | 是 |
| 拓扑： | PWM，升压（升压） |
| 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： | 800kHz ~ 1.6MHz |
| 电源电压： | 2.5 V ~ 10 V |
| 输出电压： | 36V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-5 细型，TSOT-23-5 |
| 供应商设备封装： | TSOT-23-5 |
| 包装： | 剪切带 (CT) |
| 工作温度： | -40°C ~ 85°C |
| 其它名称： | LT1937ES5 LT1937ES5#TRMCT LT1937ES5-ND |
LT1937
APPLICATIO S I FOR ATIO
2. Using a DC Voltage
For some applications, the preferred method of brightness
control is a variable DC voltage to adjust the LED current.
The dimming control using a DC voltage is shown in
Figure 7. As the DC voltage increases, the voltage drop on
R2 increases and the voltage drop on R1 decreases. Thus,
the LED current decreases. The selection of R2 and R3 will
make the current from the variable DC source much
smaller than the LED current and much larger than the FB
pin bias current. For V DC range from 0V to 2V, the selection
of resistors in Figure 7 gives dimming control of LED
current from 0mA to 15mA.
3. Using a Filtered PWM Signal
The filtered PWM signal can be considered as an adjust-
able DC voltage. It can be used to replace the variable DC
voltage source in dimming control. The circuit is shown in
Figure 8.
LT1937
FB
4. Using a Logic Signal
For applications that need to adjust the LED current in
discrete steps, a logic signal can be used as shown in
Figure 9. R1 sets the minimum LED current (when the
NMOS is off). R INC sets how much the LED current
increases when the NMOS is turned on. The selection of
R1 and R INC follows formula (1) and Table 4.
Start-up and Inrush Current
To achieve minimum start-up delay, no internal soft-start
circuit is included in LT1937. When first turned on without
an external soft-start circuit, inrush current is about 200mA
as shown in Figure 10. If soft-start is desired, the recom-
mended circuit and the waveforms are shown in Figure 11.
If both soft-start and dimming are used, a 10kHz PWM
signal on SHDN is not recommended. Use a lower fre-
quency or implement dimming through the FB pin as
shown in Figures 7, 8 or 9.
LT1937
FB
V DC
R3
90k
R2
5k
R INC
R1
6.3 ?
LOGIC
SIGNAL
2N7002
R1
1937 F07
Figure 7. Dimming Control Using a DC Voltage
1937 F09
Figure 9. Dimming Control Using a Logic Signal
I IN
100mA/DIV
LT1937
FB
FB
R3
R2
100mV/DIV
PWM
10k
90k
5k
SHDN
0.1 μ F
R1
6.3 ?
1937 F08
2V/DIV
V IN = 3.6V
THREE LEDs
50 μ s/DIV
1937 F09
15mA
Figure 8. Dimming Control Using a Filtered PWM Signal
Figure 10. Start-Up Waveforms Without Soft-Startup Circuit
1937f
7
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1937ESC6 | 制造商:LINER 制造商全称:Linear Technology 功能描述:White LED Step-Up Converter in SC70 and ThinSOT |
| LT1937ESC6#PBF | 制造商:Linear Technology 功能描述:LED DRVR 6Segment 3.3V/5V/9V 6-Pin SC-70 制造商:Linear Technology 功能描述:SP-SWREG/LED Driver, CUT TAPE White LED Step-up Converter |
| LT1937ESC6#TR | 功能描述:IC LED DRVR WHITE BCKLGT SC-70-6 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 |
| LT1937ESC6#TRM | 功能描述:IC LED DRVR WHITE BCKLGT SC-70-6 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 |
| LT1937ESC6#TRMPBF | 功能描述:IC LED DRVR WHITE BCKLGT SC-70-6 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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