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| 型号： | LT1944-1EMS#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 4/8页 |
| 文件大小： | 0K |
| 描述： | IC REG BST ADJ 0.1A/175MA 10MSOP |
| 标准包装： | 2,500 |
| 类型： | 升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 输出电压： | 1.23 V ~ 36 V |
| 输入电压： | 1.2 V ~ 15 V |
| 电流 - 输出： | 100mA，175mA |
| 同步整流器： | 无 |
| 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） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 10-MSOP |
LT1944-1
BLOCK DIAGRA
V IN
C1
L1
D1
V OUT1
C2
V OUT2
C3
D2
L2
V IN
8
V IN
2
SHDN1
10
SW1
SW2
6
SHDN2
4
V IN
R5
40k
R6
40k
R6B
40k
R5B
40k
+
A1
ENABLE
ENABLE
A1B
+
V OUT1
–
–
V OUT2
R1
(EXTERNAL)
R2
(EXTERNAL)
FB1
1
Q1
Q2
X10
R3
30k
400ns
ONE-SHOT
RESET
DRIVER
Q3
Q3B
DRIVER
1.5 μ s
ONE-SHOT
RESET
Q2B
X10
R3B
30k
Q1B
5
FB2
R1B
(EXTERNAL)
R2B
(EXTERNAL)
+
+
R4
140k
0.12 ?
0.12 ?
R4B
140k
A2
–
12mV
21mV
–
A2B
SWITCHER 1
SWITCHER 2
GND
3
9
PGND
PGND
7
1944-1 BD
Figure 1. LT1944-1 Block Diagram
OPERATIO
The LT1944-1 uses a constant off-time control scheme to
provide high efficiencies over a wide range of output
current. Operation can be best understood by referring to
the block diagram in Figure 1. Q1 and Q2 along with R3 and
R4 form a bandgap reference used to regulate the output
voltage. When the voltage at the FB1 pin is slightly above
1.23V, comparator A1 disables most of the internal cir-
cuitry. Output current is then provided by capacitor C2,
which slowly discharges until the voltage at the FB1 pin
drops below the lower hysteresis point of A1 (typical
hysteresis at the FB pin is 8mV). A1 then enables the
internal circuitry, turns on power switch Q3, and the
current in inductor L1 begins ramping up. Once the switch
current reaches 100mA, comparator A2 resets the one-
shot, which turns off Q3 for 400ns. L1 then delivers
current to the output through diode D1 as the inductor
current ramps down. Q3 turns on again and the inductor
current ramps back up to 100mA, then A2 resets the one-
shot, again allowing L1 to deliver current to the output.
This switching action continues until the output voltage is
charged up (until the FB1 pin reaches 1.23V), then A1
turns off the internal circuitry and the cycle repeats. The
LT1944-1 contains additional circuitry to provide protec-
tion during start-up and under short-circuit conditions.
When the FB1 pin voltage is less than approximately
600mV, the switch off-time is increased to 1.5 μ s and the
current limit is reduced to around 70mA (70% of its
normal value). This reduces the average inductor current
and helps minimize the power dissipation in the power
switch and in the external inductor and diode.
The second switching regulator operates in the same
manner, but with a 175mA current limit and an off-time of
1.5 μ s. With this longer off-time, switcher 2 is ideal for very
low duty cycle applications (i.e. Li-Ion to 5V boost
converters).
4
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1944EMS | 功能描述:IC REG BOOST ADJ 0.35A DL 10MSOP 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:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LT1944EMS#PBF | 功能描述:IC REG BOOST ADJ 0.35A DL 10MSOP 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 |
| LT1944EMS#TR | 功能描述:IC REG BOOST ADJ 0.35A DL 10MSOP 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:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LT1944EMS#TRPBF | 功能描述:IC REG BOOST ADJ 0.35A DL 10MSOP 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:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LT1944EMSPBF | 制造商:Linear Technology 功能描述:Conv DC-DC Dual Step-Up 1.2-15V MSOP10 |
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