参数资料
型号: LT1776C
厂商: Linear Technology Corporation
元件分类: 基准电压源/电流源
英文描述: RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS
中文描述: 抗辐射高效,5安培开关稳压器
文件页数: 15/20页
文件大小: 147K
代理商: LT1776C
15
LT1776
TYPICAL APPLICATIO
N
S
chosen to be significantly above the SHDN pin input
current to minimize its error contribution, but signifi-
cantly below the typical 3.8mA the LT1776 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
voltage minus 1.25V applied across it. (The 2.5
μ
A factor
is an allowance to minimize error due to SHDN pin input
current.)
Behavior is as follows: Normal operation is observed at the
nominal input voltage of 40V. As the input voltage is
decreased to roughly 32V, switching action will stop, V
OUT
will drop to zero, and the LT1776 will draw its V
IN
and V
CC
quiescent currents from the V
IN
supply. At a much lower
input voltage, typically 14V 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 lockoutthreshold is relatively accurate includ-
ing temperature effects, the SHDN pin shutdownthresh-
old is more coarse, and exhibits considerably more
temperature drift. Nevertheless the shutdown threshold
will always be well below the lockout threshold.)
Minimum Size Inductor Application
Figure 4a employs power path parts that are capable of
delivering the full rated output capability of the LT1776.
Potential users with low output current requirements may
be interested in substituting a physically smaller and less
costly power inductor. The circuit shown in Figure 6a is
topologically identical to the basic application, but speci-
fies a much smaller inductor. This circuit is capable of
delivering up to 400mA at 5V, or, up to 500mA at 3.3V. The
only disadvantage is that due to the increased resistance
in the inductor, the circuit is no longer capable of with-
standing indefinite short circuits to ground. The LT1776
will still current limit at its nominal I
LIM
value, but this will
overheat the inductor. Momentary short circuits of a few
seconds or less can still be tolerated. Typical efficiency is
shown in Figure 6b.
C1
1776 F05
V
IN
+
C2
+
D1
R1
V
OUT
R2
R3
L1
C3
R4
158k
1%
R5
6.19k
1%
C4
C5
V
IN
V
CC
V
SW
LT1776
FB
V
C
SHDN
SYNC
2
5
4
3
7
8
1
6
GND
Figure 5. User Programmable Undervoltage Lockout
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LT1776CN8#PBF 功能描述:IC REG BUCK ADJ 0.7A 8DIP 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
LT1776CS8 功能描述:IC REG BUCK ADJ 0.7A 8SOIC 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
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