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| 型号： | LT3494EDDB#TRMPBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BOOST ADJ 0.18A 8DFN |
| 标准包装： | 1 |
| 类型： | 升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.23 V ~ 38 V |
| 输入电压： | 2.3 V ~ 16 V |
| PWM 型： | 混合物 |
| 电流 - 输出： | 180mA |
| 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-WFDFN 裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 8-DFN（3x2） |
| 产品目录页面： | 1331 (CN2011-ZH PDF) |
| 其它名称： | LT3494EDDB#TRMPBFDKR |
LT3494/LT3494A
APPLICATIONS INFORMATION
Connecting the Load to the CAP Node
The ef?ciency of the converter can be improved by con-
necting the load to the CAP pin instead of the V OUT pin.
The power loss in the PMOS disconnect circuit is then
made negligible. By connecting the feedback resistor to
the V OUT pin, no quiescent current will be consumed in the
feedback resistor string during shutdown since the PMOS
If the inductor ripple current is greater than the peak cur-
rent, then the circuit will only operate in discontinuous
conduction mode. The inductor value should be increased
so that I RIPPLE < I PK . An application circuit can be designed
to operate only in discontinuous mode, but the output
current capability will be reduced.
Step 3: Calculate the average input current:
transistor will be open (see Figure 3). The disadvantage
of this method is that the CAP node cannot go to ground
during shutdown, but will be limited to around a diode
I IN ( AVG ) = I PK –
I RIPPLE
2
amps
drop below V CC . Loads connected to the part should only
sink current. Never force external power supplies onto
Step 4: Calculate the nominal output current:
I OUT ( NOM ) =
the CAP or V OUT pins. The larger value output capacitor
(2.2μF to 10μF) should be placed on the node to which
the load is connected.
I IN ( AVG ) ? V IN ? 0 . 75
V OUT
Step 5: Derate output current:
amps
1
SW
8
CAP
C1
I LOAD
I OUT = I OUT(NOM) ? 0.7 amps
3
V CC
V OUT
7
For low output voltages the output current capability will
5
4
LT3494
SHDN FB
CTRL GND
6
2
3494 F03
be increased. When using output disconnect (load cur-
rent taken from V OUT ), these higher currents will cause
the drop in the PMOS switch to be higher resulting in
reduced output current capability than those predicted
V IN ? 400 ? 10 – 9
I PK = I LIMIT + amps
( V OUT + 1 – V IN ) ? 150 ? 10 – 9
I RIPPLE = amps
Figure 3. Improved Ef?ciency
Maximum Output Load Current
The maximum output current of a particular LT3494/
LT3494A circuit is a function of several circuit variables.
The following method can be helpful in predicting the
maximum load current for a given circuit:
Step 1: Calculate the peak inductor current:
L
where I LIMIT is 0.180A and 0.350A for the LT3494 and
LT3494A respectively. L is the inductance value in Henrys
and V IN is the input voltage to the boost circuit.
Step 2: Calculate the inductor ripple current:
L
where V OUT is the desired output voltage.
by the preceding equations.
Inrush Current
When V CC is stepped from ground to the operating volt-
age while the output capacitor is discharged, a higher
level of inrush current may ?ow through the inductor
and integrated Schottky diode into the output capacitor.
Conditions that increase inrush current include a larger
more abrupt voltage step at V IN , a larger output capacitor
tied to the CAP pin and an inductor with a low saturation
current. While the internal diode is designed to handle
such events, the inrush current should not be allowed to
exceed 1A. For circuits that use output capacitor values
within the recommended range and have input voltages
of less than 5V, inrush current remains low, posing no
hazard to the device. In cases where there are large steps
at V CC (more than 5V) and/or a large capacitor is used
at the CAP pin, inrush current should be measured to
ensure safe operation. The LT3494A circuits experience
higher levels of current during start-up and steady-state
operation. An external diode placed from the SW pin to
3494fb
9
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| LT3495 | 制造商:LINER 制造商全称:Linear Technology 功能描述:650mA/350mA Micropower Low Noise Boost Converter with Output Disconnect |
| LT3495-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:650mA/350mA Micropower Low Noise Boost Converter with Output Disconnect |
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| LT3495BEDDB#TRMPBF | 功能描述:IC REG BOOST ADJ 0.65A 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: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 |
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