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| 型号： | LT1947EMS#TR |
| 厂商： | Linear Technology |
| 文件页数： | 7/12页 |
| 文件大小： | 0K |
| 描述： | IC SW REG TFT-LCD TRPL ADJ10MSOP |
| 标准包装： | 2,500 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 2.7 V ~ 8 V |
| 输出数： | 3 |
| 输出电压： | 最高可调至 30V |
| 工作温度： | -40°C ~ 85°C |
| 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-MSOP |
| 包装： | 带卷 (TR) |
| 其它名称： | LT1947EMSTR |
LT1947
OPERATIO
To best understand operation of the LT1947, please refer
to the LT1947 Block Diagram. The device contains two
switching regulators, a timer and a high side switch. Three
outputs can be generated: an adjustable AV DD output, a
charge-pumped inversion of the AV DD output called V OFF ,
and a time delayed adjustable output called V ON . Q3 keeps
V ON off for an externally set time interval, set by a capacitor
connected to the C T pin.
The switching frequency of both switchers is 3MHz, set
internally. The switchers are current mode and are inter-
nally compensated. The main AV DD switcher is current
limited at 1.1A, while the second V ON switcher is limited to
350mA. They share the same 1.26V reference voltage.
When the input voltage is below approximately 2.7V, an
undervoltage lockout circuit disables switching.
When AV DD is less than its final voltage, Q4 is turned on,
holding the C T pin at ground. When AV DD reaches final
value, Q4 lets go of the C T pin, allowing the 5.5 μ A current
source to charge the external capacitor, C T . When the
voltage on the C T pin reaches 1.28V, Q3 turns on,
connecting V O2 to V ON . Capacitor value can be calculated
using the following formula:
R3
C = (5.5 μ A ? t DELAY )/1.28V
A 10nF capacitor results in approximately 2.3ms of delay.
Layout Hints
The high speed operation of the LT1947 mandates careful
attention to layout for proper performance. Be sure to keep
input capacitor C1 as close as possible to the IC and
minimize trace area and length at the SW and FB pins.
Always use a ground plane under the switching regulator
to minimize interplane coupling. Figure 2 shows the rec-
ommended component placement.
The exposed pad of the MSE package must be soldered to
the PCB and electrically connected to ground. Thermal
vias to a large ground plane will lower the thermal resis-
tance.
Soft-Start
For applications requiring soft-start, a circuit consisting of
R SS and C SS tied to the SHDN pin can be used, as shown
in Figure 3. For a combination of 33.2k/33nF, AV DD rises
to its final value in approximately 3ms.
GND
R4
R1
1
R2
10
V ON
C5
2
3
LT1947
9
8
L1
4
5
7
6
SHDN
C1
V IN
C6
C3
L2
V IN
D2
AV DD
D1
D3
C2
C4
D4
GND
V OFF
1947 F02
Figure 2. Recommended Component Placement
1947fa
7
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1948 | 制造商:LINEAR 制造商全称:LINEAR 功能描述:DC/DC Converter for TFT-LCD Panels |
| LT1948EMS8 | 制造商:LINER 制造商全称:Linear Technology 功能描述:DC/DC Converter for TFT-LCD Panels |
| LT1949 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.4A, 1.5MHz Synchronous Step-Up DC/DC Converter with Output Disconnect |
| LT1949-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.4A, 1.5MHz Synchronous Step-Up DC/DC Converter with Output Disconnect |
| LT1949-1EMS8 | 功能描述:IC REG BOOST ADJ 1A 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
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