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参数资料
| 型号： | LTC3542ES6#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 8/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ TSOT23-6 |
| 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： | 0.6 V ~ 5.5 V |
| 输入电压： | 2.5 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 2.25MHz |
| 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： | SOT-23-6 细型，TSOT-23-6 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | TSOT-23-6 |
LTC3542
APPLICATIONS INFORMATION
A general LTC3542 application circuit is shown in Figure1.
External component selection is driven by the load require-
ment and begins with the selection of the inductor L. Once
the inductor is chosen, C IN and C OUT can be selected.
the burst clamp. Lower inductor values result in higher
ripple current which causes the transition to occur at lower
load currents. This causes a dip in ef?ciency in the upper
range of low current operation. In Burst Mode operation,
V IN
2.7V TO 5.5V
C IN
V IN SW
LTC3542
RUN V FB
MODE/SYNC
GND
R1
L
C F
R2
V OUT
C OUT
3542 F01
lower inductance values cause the burst frequency to
increase.
Inductor Core Selection
Different core materials and shapes change the size/current
and price/current relationships of an inductor. Toroid or
shielded pot cores in ferrite or permalloy materials are small
and don’t radiate much energy, but generally cost more
Figure 1. LTC3542 General Schematic
Inductor Selection
The inductor value has a direct effect on ripple current Δ I L ,
which decreases with higher inductance and increases with
higher V IN or V OUT , as shown in following equation:
than powdered iron core inductors with similar electrical
characteristics. The choice of which style inductor to use
often depends more on the price vs size requirements
and any radiated ?eld/EMI requirements than on what the
LTC3542 requires to operate. Table 1 shows some typi-
cal surface mount inductors that work well in LTC3542
1 – OUT ?
Δ I L =
V OUT ?
? O ? L ? ?
V ?
V IN ?
applications.
Input Capacitor (C IN ) Selection
where f O is the switching frequency. A reasonable starting
point for setting ripple current is Δ I L = 0.4 ? I OUT(MAX) ,
where I OUT(MAX) is 500mA. The largest ripple current Δ I L
occurs at the maximum input voltage. To guarantee that
the ripple current stays below a speci?ed maximum, the
inductor value should be chosen according to the follow-
In continuous mode, the input current of the converter is a
square wave with a duty cycle of approximately V OUT /V IN .
To prevent large voltage transients, a low equivalent series
resistance (ESR) input capacitor sized for the maximum
RMS current must be used. The maximum RMS capacitor
current is given by:
V OUT ?
? O L ?
? Δ I
V IN ( MAX ) ?
V OUT ( V IN OUT )
ing equation:
L = ? 1 –
V OUT ?
?
– V
I RMS ≈ I MAX
V IN
where the maximum average output current I MAX equals
The DC current rating of the inductor should be at least
equal to the maximum load current plus half the ripple
current to prevent core saturation. Thus, a 600mA rated
inductor should be enough for most applications (500mA
+ 100mA). For better ef?ciency, chose a low DC-resistance
inductor.
The inductor value will also have an effect on Burst Mode
operation. The transition to low current operation begins
when the inductor’s peak current falls below a level set by
the peak current minus half the peak-to-peak ripple cur-
rent, I MAX = I LIM – Δ I L /2. This formula has a maximum at
V IN = 2V OUT , where I RMS = I OUT /2. This simple worst-case
is commonly used to design because even signi?cant
deviations do not offer much relief. Note that capacitor
manufacturer’s ripple current ratings are often based on
only 2000 hours life time. This makes it advisable to further
derate the capacitor, or choose a capacitor rated at a higher
temperature than required. Several capacitors may also be
paralleled to meet the size or height requirements of the
3542fa
8
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| LTC3542IDC#TRMPBF | 功能描述:IC REG BUCK SYNC ADJ 0.5A 6DFN 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 |
| LTC3542IDC#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 0.5A 6DFN 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 |
| LTC3542IDC-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA, 2.25MHz Synchronous Step-Down DC/DC Converter |
| LTC3542IDC-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA, 2.25MHz Synchronous Step-Down DC/DC Converter |
| LTC3542IS6#PBF | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 2.5V to 5.5V 6-Pin TSOT-23 制造商:Linear Technology 功能描述:DP-SWREG/Monolithic, Cut Tape 500mA, 2.25MHz Synchronous Step-Down DC/DC Convert |
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