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| 型号： | LTC3442EDE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BOOST SYNC ADJ 12DFN |
| 标准包装： | 91 |
| 类型： | 降压（降压），升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 2.4 V ~ 5.25 V |
| 输入电压： | 2.4 V ~ 5.5 V |
| PWM 型： | Burst Mode? |
| 频率 - 开关： | 300kHz ~ 2MHz |
| 电流 - 输出： | 1.2A |
| 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： | 12-WFDFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 12-DFN（4x3） |
| 产品目录页面： | 1334 (CN2011-ZH PDF) |
LTC3442
OPERATION
dI – V OUT
BoostRegion(V IN <V OUT )
Switch A is always on and switch B is always off during
this mode. When the internal control voltage, V CI , is above
voltage V3, switch pair CD will alternately switch to provide
a boosted output voltage. This operation is typical to a
synchronous boost regulator. The maximum duty cycle
of the converter is limited to 88% typical and is reached
when V CI is above V4.
V IN
9
A
B
4
SW1
–
L
5
dt L
+
6
SW2
V OUT
8
D
C
900mA
0mA
T2
3442 F04
GND
n ? I LOAD
35μA + I LOAD
I OUT(MAX)BURST ≈
0.2 ? V IN
V OUT + V IN
BURSTMODEOPERATION
Burst Mode operation occurs when the IC delivers energy
to the output until it is regulated and then goes into a sleep
mode where the outputs are off and the IC is consuming
only 35μA of quiescent current from V IN . In this mode the
output ripple has a variable frequency component that
depends upon load current, and will typically be about
2% peak-to-peak. Burst Mode operation ripple can be
reduced slightly by using more output capacitance (47μF
or greater). Another method of reducing Burst Mode
operation ripple is to place a small feedforward capacitor
across the upper resistor in the V OUT feedback divider
network (as in Type?III compensation).
During the period where the device is delivering energy to
the output, the peak switch current will be equal to 900mA
typical and the inductor current will terminate at zero
current for each cycle. In this mode the typical maximum
average output current is given by:
A
Note that the peak efficiency during Burst Mode operation
is less than the peak efficiency during fixed frequency
Figure 4. Inductor Discharge Cycle During Burst Mode Operation
because the part enters full-time 4-switch mode (when
servicing the output) with discontinuous inductor cur-
rent as illustrated in Figures 3 and 4. During Burst Mode
operation, the control loop is nonlinear and cannot utilize
the control voltage from the error amp to determine the
control mode, therefore full-time 4-switch mode is required
to maintain the buck/boost function. The efficiency below
1mA becomes dominated primarily by the quiescent cur-
rent. The Burst Mode operation efficiency is given by:
EFFICIENCY ?
where n is typically 82% during Burst Mode operation.
Automatic Burst Mode Operation Control
Burst Mode operation can be automatic or manually con-
trolled with a single pin. In automatic mode, the IC will
enter Burst Mode operation at light load and return to fixed
frequency operation at heavier loads. The load current at
which the mode transition occurs is programmed using
a single external resistor from the BURST pin to ground,
according to the following equations:
V IN
9
V OUT
8
Enter Burst Mode: I =
17.6
R BURST
A
4
SW1
+
dI
dt
L
V IN
L
–
6
SW2
D
900mA
Leave Burst Mode: I =
22.4
R BURST
B
5
C
0mA
T1
3442 F03
where R BURST is in kΩ and I BURST is the load transition
current in Amps. Do not use values of R BURST greater
than 250k.
GND
Figure 3. Inductor Charge Cycle During Burst Mode Operation
3442fb
10
For more information www.linear.com/LTC3442
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相关代理商/技术参数 |
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|---|---|
| LTC3443 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Current Micropower 600kHz Synchronous Buck-Boost DC/DC Converter |
| LTC3443EDE | 功能描述:IC REG BUCK BOOST SYNC ADJ 12DFN 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 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 裸露焊盘 |
| LTC3443EDE#PBF | 功能描述:IC REG BUCK BOOST SYNC ADJ 12DFN 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 |
| LTC3443EDE#TR | 功能描述:IC REG BUCK BOOST SYNC ADJ 12DFN 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 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 裸露焊盘 |
| LTC3443EDE#TRPBF | 功能描述:IC REG BUCK BOOST SYNC ADJ 12DFN 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 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 裸露焊盘 |
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