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参数资料
| 型号： | LTC3251EMSE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SWITCHED CAP 10MSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压），切换电容（充电泵） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.9 V ~ 1.6 V |
| 输入电压： | 2.7 V ~ 5.5 V |
| PWM 型： | 多重 |
| 频率 - 开关： | 1MHz ~ 1.6MHz |
| 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： | 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 |
LTC3251/
LTC3251-1.2/LTC3251-1.5
OPERATIO
(Refer to Block Diagram)
4.7 μ H
10nH*
10nH*
V IN
IN
SW
V OUT
V IN
IN
OUT
V OUT
10 μ F
22 μ F
1 μ F
1 μ F
LTC3251
10 μ F
1 μ F
COMP
GND
FB
*10nH = 1cm OF PCB TRACE
1 μ F
C1 +
C1 –
FB
C2 +
C2 –
1 μ F
*10nH = 1cm OF PCB TRACE
3251 F01a
GND
3251 F02a
Figure 1a. Conventional Buck Switching Converter
–40
–50
–60
–70
–80
–90
START FREQ: 100kHz RBW: 10kHz STOP FREQ: 30MHz
3251 F01b
Figure 1b. Conventional Buck Converter Output Noise
Spectrum with 22 μ F Output Capacitor (I O = 500mA)
–40
–50
–60
–70
–80
–40
–50
–60
–70
–80
–90
–40
–50
–60
–70
–80
Figure 2a. LTC3251 Buck Converter
START FREQ: 100kHz RBW: 10kHz STOP FREQ: 30MHz
3251 F02b
Figure 2b. LTC3251 Output Noise Spectrum
with 10 μ F Output Capacitor (I O = 500mA)
–90
START FREQ: 100kHz RBW: 10kHz STOP FREQ: 30MHz
3251 F01c
–90
START FREQ: 100kHz RBW: 10kHz STOP FREQ: 30MHz
3251 F02c
Figure 1c. Conventional Buck Converter Input Noise
Spectrum with 10 μ F Input Capacitor (I O = 500mA)
Unlike conventional buck converters, the LTC3251’s inter-
nal oscillator is designed to produce a clock pulse whose
period is random on a cycle-by-cycle basis, but fixed
between 1MHz and 1.6MHz. This has the benefit of spread-
ing the switching noise over a range of frequencies, thus
significantly reducing the peak noise. Figures 2b and 2c
are the input and output noise spectrums for the LTC3251
of Figure 2a with V IN = 3.6V, V OUT = 1.5V and I OUT =
500mA. Note the significant reduction in peak output
noise (>20dBm) with only 1/2 the output capacitance and
the virtual elimination of input harmonics with only 1/10
the input capacitance. Spread spectrum operation is used
exclusively in “continuous” mode and for output currents
greater than about 50mA in Burst Mode operation.
Figure 2c. LTC3251 Input Noise Spectrum
with 1 μ F Input Capacitor (I O = 500mA)
Low Current Burst Mode Operation
To improve efficiency at low output currents, a Burst Mode
function is included in the LTC3251 family of parts. An
output current sense is used to detect when the required
output current drops below an internally set threshold
(50mA typ). When this occurs, the part shuts down the
internal oscillator and goes into a low current operating
state. The part will remain in the low current operating
state until the output voltage has dropped enough to
require another burst of current. When the output current
exceeds 50mA, the part will operate in continuous mode.
Unlike traditional charge pumps, where the burst current
is dependant on many factors (i.e., supply, switch strength,
32511215fb
9
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| LTC3252 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise Dual Supply |
| LTC3252EDE | 功能描述:IC REG BUCK SWITCHED CAP 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 |
| LTC3252EDE#PBF | 功能描述:IC REG BUCK SWITCHED CAP 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 |
| LTC3252EDE#TR | 功能描述:IC REG BUCK SWITCHED CAP 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 |
| LTC3252EDE#TRPBF | 功能描述:IC REG BUCK SWITCHED CAP 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:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
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