参数资料
| 型号： | LT1912EMSE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 14/24页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 2A 10MSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.79 V ~ 20 V |
| 输入电压： | 3.6 V ~ 36 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz ~ 500kHz |
| 电流 - 输出： | 2A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 10-MSOP |
LT1912
APPLICATIONS INFORMATION
C3
C3
the boost capacitor is charged with the energy stored in
the inductor, the circuit will rely on some minimum load
current to get the boost circuit running properly. This
minimum load will depend on input and output volt-
ages, and on the arrangement of the boost circuit. The
minimum load generally goes to zero once the circuit has
started. Figure 5 shows a plot of minimum load to start
and to run as a function of input voltage. In many cases
the discharged output capacitor will present a load to the
switcher, which will allow it to start. The plots show the
worst-case situation where V IN is ramping very slowly.
For lower start-up voltage, the boost diode can be tied to
V IN ; however, this restricts the input range to one-half of
the absolute maximum rating of the BOOST pin.
V IN
4.7μF
V IN
V IN
V IN
BD
BOOST
LT1912
SW
GND
(4a) For V OUT > 2.8V
BD
BOOST
LT1912
D2
V OUT
V OUT
At light loads, the inductor current becomes discontinu-
ous and the effective duty cycle can be very high. This
reduces the minimum input voltage to approximately
300mV above V OUT . At higher load currents, the inductor
current is continuous and the duty cycle is limited by the
maximum duty cycle of the LT1912, requiring a higher
input voltage to maintain regulation.
4.7μF
SW
GND
(4b) For 2.5V < V OUT < 2.8V
BD
V OUT
Soft-Start
V IN
V IN
BOOST
LT1912
C3
The RUN/SS pin can be used to soft-start the LT1912,
reducing the maximum input current during start-up.
The RUN/SS pin is driven through an external RC filter to
create a voltage ramp at this pin. Figure 6 shows the start-
up and shutdown waveforms with the soft-start circuit.
By choosing a large RC time constant, the peak start-up
current can be reduced to the current that is required to
regulate the output, with no overshoot. Choose the value
of the resistor so that it can supply 20μA when the RUN/
SS pin reaches 2.5V.
Synchronization
Synchronizing the LT1912 oscillator to an external fre-
quency can be done by connecting a square wave (with
20% to 80% duty cycle) to the SYNC pin. The square
wave amplitude should have valleys that are below 0.3V
and peaks that are above 0.8V (up to 6V).
The LT1912 may be synchronized over a 250kHz to 500kHz
range. The R T resistor should be chosen to set the LT1912
switching frequency 20% below the lowest synchronization
SW
4.7μF GND
1912 FO4
(4c) For V OUT < 2.5V; V IN(MAX) = 30V
Figure 4. Three Circuits For Generating The Boost Voltage
input. For example, if the synchronization signal will be
250kHz and higher, the R T should be chosen for 200kHz.
To assure reliable and safe operation the LT1912 will only
synchronize when the output voltage is near regulation. It
is therefore necessary to choose a large enough inductor
value to supply the required output current at the frequency
set by the R T resistor. See Inductor Selection section. It
is also important to note that slope compensation is set
by the R T value: When the sync frequency is much higher
than the one set by R T , the slope compensation will be
significantly reduced which may require a larger inductor
value to prevent subharmonic oscillation.
1912fa
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1913 | 制造商:LINER 制造商全称:Linear Technology 功能描述:25V, 3.5A, 2.4MHz Step-Down Switching Regulator |
| LT1913EDD#PBF | 功能描述:IC REG BUCK ADJ 3.5A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LT1913EDD#TRPBF | 功能描述:IC REG BUCK ADJ 3.5A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT1913EDD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:25V, 3.5A, 2.4MHz Step-Down Switching Regulator |
| LT1913EDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:25V, 3.5A, 2.4MHz Step-Down Switching Regulator |
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