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参数资料
| 型号： | LTC3251EMSE-1.5#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/16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： | 固定 |
| 输出数： | 1 |
| 输出电压： | 1.5V |
| 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)
At moderate to high output power the switching losses
and quiescent current of the LTC3251 family is negligible
and the expression above is valid. For example with V IN =
3.6V, I OUT = 200mA and V OUT regulating to 1.5V the
measured efficiency is 81% which is in close agreement
with the theoretical 83.3% calculation.
Programming the LTC3251 Output Voltage (FB Pin)
The LTC3251 is programmed to an arbitrary output volt-
age via an external resistive divider. Figure 7 shows the
required voltage divider connection. The voltage divider
ratio is given by the expression:
For a 1.5V output, R O is 0.085 ? , which produces a 40mV
output change for a 500mA load current step. Thus, the
user may want to target an unloaded output voltage
slightly higher than desired to compensate for the output
load conditions. The output may be programmed for
regulation voltages of 0.9V to 1.6V.
Since the LTC3251 employs a 2-to-1 charge pump archi-
tecture, it is not possible to achieve output voltages
greater than half the available input voltage. The minimum
V IN supply required for regulation can be determined by
the following equation:
V IN(MIN) ≥ 2 ? (V OUT(MIN) + I OUT ? R OL )
= OUT – 1
R A
R B
V
0 . 8 V
The compensation capacitor (C A ) is necessary to counter-
act the pole caused by the large valued resistors R A and R B ,
and the input capacitance of the FB pin. For best results, C A
( )
0.8V 1 + A
V OUT
LTC3251
FB
C A
R A
R B
C OUT
V OUT
R
R B
should be 5pF for all R A or R B greater than 10k and can be
omitted if both R A and R B are less than 10k.
Disabling Spread Spectrum Operation on the
GND
3251 F07
Figure 7. Programming the LTC3251
Typical values for total voltage divider resistance can
range from several k ? s up to 1M ? .
The user may want to consider load regulation when
setting the desired output voltage. The closed loop output
impedance of the LTC3251 is approximately:
LTC3251-1.2/LTC3251-1.5 (MODE Pin)
Spread spectrum operation can be disabled by driving
MODE high. When Mode is high, switching takes place at
the maximum operating frequency (typ 1.6MHz). The
advantage of spread spectrum operation is that it reduces
the peak noise at and above the operating frequency at the
expense of a slightly increased noise floor and slightly
increased low frequency ripple caused by the converter
compensating for the changing operating frequency. Us-
ers who do not need the peak noise reduction gained by
R O ? 0 . 045 ? ?
V OUT
0 . 8 V
using spread spectrum may wish to disable spread spec-
trum, thus improving the low frequency input/output
ripple.
32511215fb
13
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相关代理商/技术参数 |
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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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