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参数资料
| 型号： | LT1777 |
| 厂商： | Linear Technology Corporation |
| 英文描述： | Low Noise Step-Down Switching Regulator(低噪声，5V输出步降开关稳压器) |
| 中文描述： | 低噪声降压型开关稳压器（低噪声，5V的输出步降开关稳压器） |
| 文件页数： | 12/24页 |
| 文件大小： | 275K |
| 代理商： | LT1777 |
12
LT1777
APPLICATIO
S I
N
FOR
ATIO
U
W
U
voltage of 12V, and then 36V. Once again the circuit is the
Typical Application shown on the first page of this data
sheet, with an output load of 400mA.
Figure 5a, with V
IN
of 12V, shows a relatively rectangular
voltage waveform. The limited voltage slew rate still allows
for nearly vertical switching edges, so little power is
wasted. A positive-going step before the leading edge and
a negative-going step after the trailing edge can be seen.
These are evidence of the internal current limiting circuitry
at work.
Figure 5b, with V
IN
of 36V, shows a substantially
nonrectangular waveform. The limited voltage slew rate is
clearly evident as transitions take a few hundred nanosec-
onds. Efficiency (P
OUT
/P
IN
) is reduced as a result of the
slower transitions. For comparison purposes, the oscillo-
scope photo in Figure 6 shows the performance of the high
efficiency LT1676. Voltage transitions are well under
100ns and the waveform appears quite rectangular.
1
0MHz to 20MHz (2MHz/DIV)
1777 F04a
(a) LT1676 for Comparison
1
0MHz to 20MHz (2MHz/DIV)
1777 F04b
(b) LT1777 with L
SENSE
= 0
μ
H
1
0MHz to 20MHz (2MHz/DIV)
1777 F04c
(c) LT1777 with L
SENSE
= 2.2
μ
H
Voltage Waveform Behavior
Unlike current behavior, voltage slew rate of the LT1777 is
not adjustable by the user. No component selection or
other action is required. Nevertheless, it is instructive to
examine typical behavior. The oscilloscope photos in
Figure 5 show the V
SW
voltage waveform with an input
2
1
μ
s/DIV
1777 F05a
(a) V
IN
= 12V
GND
Figure 5. V
SW
Node Voltage Behavior
1
500ns/DIV
1777 F05b
(b) V
IN
= 36V
GND
Figure 4. Spectral Analysis of Current Waveforms in
Figures 2 and 3. (V
IN
= 24V, V
OUT
= 5V, I
OUT
= 400mA)
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1777C | 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise Step-Down Switching Regulator |
| LT1777CS | 功能描述:IC REG BUCK ADJ 0.7A 16SOIC 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: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 |
| LT1777CS#PBF | 功能描述:IC REG BUCK ADJ 0.7A 16SOIC 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 |
| LT1777CS#TR | 功能描述:IC REG BUCK ADJ 0.7A 16SOIC 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: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 |
| LT1777CS#TRPBF | 功能描述:IC REG BUCK ADJ 0.7A 16SOIC 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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