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| 型号： | LT1777CS#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 22/24页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 0.7A 16SOIC |
| 标准包装： | 50 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.24 V ~ 30 V |
| 输入电压： | 12 V ~ 48 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz |
| 电流 - 输出： | 700mA |
| 同步整流器： | 无 |
| 工作温度： | 0°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 16-SOIC |
LT1777
TYPICAL APPLICATIO N S
V OUT NODE
AC COUPLED
2mV/DIV
V OUT NODE
AC COUPLED
2mV/DIV
2 μ s/DIV
(a) Before Output Filter
1777 F13a
2 μ s/DIV
(b) After Output Filter
1777 F14b
Figure 14. Output Node Ripple
User Programmable Undervoltage Lockout
Figure 15 uses a resistor divider between V IN and ground
to drive the SHDN node. This is a simple, cost-effective
way to add a user-programmable undervoltage lockout
(UVLO) function. Resistor R5 is chosen to have approxi-
mately 200 μ A through it at the nominal SHDN pin lockout
threshold of roughly 1.25V. The somewhat arbitrary value
of 200 μ A was chosen to be significantly above the SHDN
pin input current to minimize its error contribution, but
significantly below the typical 2.5mA the LT1777 draws in
lockout mode. Resistor R4 is then chosen to yield this
same 200 μ A, less 2.5 μ A, with the desired V IN UVLO volt-
age minus 1.25V across it. (The 2.5mA factor is an allow-
ance to minimize error due to SHDN pin input current.)
V IN
R4
84.5k
Behavior is as follows: Normal operation is observed at the
nominal input voltage of 24V. As the input voltage is
decreased to roughly 18V, switching action will stop, V OUT
will drop to zero, and the LT1777 will draw its V IN and V CC
quiescent currents from the V IN supply. At a lower input
voltage, typically 10V or so at 25 ° C, the voltage on the
SHDN pin will drop to the shutdown threshold, and the part
will draw its shutdown current only from the V IN rail. The
resistive divider of R4 and R5 will continue to draw power
from V IN . (The user should be aware that while the SHDN
pin lockout threshold is relatively accurate including
temperature effects, the SHDN pin shutdown threshold is
more coarse, and exhibits considerably more temperature
drift. Nevertheless the shutdown threshold will always be
well below the lockout threshold.)
LT1777
1%
R5
6.19k
1%
C5
100pF
SHDN
1777 F15
Figure 15. User Programmable UVLO
22
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1777I | 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise Step-Down Switching Regulator |
| LT1777IS | 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: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 |
| LT1777IS#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: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 |
| LT1777IS#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC |
| LT1777IS#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: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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