参数资料
型号: LT3431IFE#TRPBF
厂商: Linear Technology
文件页数: 16/28页
文件大小: 0K
描述: IC REG BUCK ADJ 3A 16TSSOP
标准包装: 2,500
类型: 降压(降压)
输出类型: 可调式
输出数: 1
输出电压: 1.2 V ~ 48 V
输入电压: 5.5 V ~ 60 V
PWM 型: 电流模式
频率 - 开关: 500kHz
电流 - 输出: 3A
同步整流器:
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: 16-TSSOP(0.173",4.40mm)裸露焊盘
包装: 带卷 (TR)
供应商设备封装: 16-TSSOP-EP
LT3431
APPLICATIO S I FOR ATIO
R FB
LT3431
L1
INPUT
IN
2.38V
+
V SW
OUTPUT
STANDBY
R HI
5.5 μ A
SHDN
+
TOTAL
SHUTDOWN
+
C1
C2
R LO
0.4V
GND
3431 F04
Figure 4. Undervoltage Lockout
R LO ( IN ? 2 . 38 V )
(
)
[ ( ) ]
2 . 38 – 25 k ( )
25 k ( )
(
)
Thresholdvoltageforlockoutisabout2.38V.A5.5μAbias
current flows out of the pin at this threshold. The internally
generated current is used to force a default high state on
the shutdown pin if the pin is left open. When low shut-
down current is not an issue, the error due to this current
can be minimized by making R LO 10k or less. If shutdown
current is an issue, R LO can be raised to 100k, but the error
due to initial bias current and changes with temperature
should be considered.
R LO = 10 k to 100k ( 25k suggested )
V
R HI =
2 . 38 V ? R LO 5 . 5 μ A
V IN = Minimum input voltage
Keep the connections from the resistors to the shutdown
pin short and make sure that interplane or surface capaci-
tance to the switching nodes are minimized. If high
resistor values are used, the shutdown pin should be
bypassed with a 1000pF capacitor to prevent coupling
problems from the switch node. If hysteresis is desired in
the undervoltage lockout point, a resistor R FB can be
added to the output node. Resistor values can be calcu-
lated from:
25k suggested for R LO
V IN = Input voltage at which switching stops as input
voltage descends to trip level
? V = Hysteresis in input voltage level
Example: output voltage is 5V, switching is to stop if input
voltage drops below 12V and should not restart unless
input rises back to 13.5V. ? V is therefore 1.5V and
V IN = 12V. Let R LO = 25k.
25 k 12 ? 2 . 38 1 . 5 / 5 + 1 + 1 . 5
R HI =
5 . 5 μ A
10 . 41
= = 116 k
2 . 24
R FB = 116 k 5 / 1 . 5 = 387 k
SYNCHRONIZING
The SYNC input must pass from a logic level low, through
the maximum synchronization threshold with a duty cycle
between 10% and 90%. The input can be driven directly
from a logic level output. The synchronizing range is equal
to initial operating frequency up to 700kHz. This means
that minimum practical sync frequency is equal to the
[ ( )
(
)
R HI =
R LO V IN ? 2 . 38 ? V / V OUT + 1 + ? V
2 . 38 ? R LO 5 . 5 μ A
R FB = ( R HI )( V OUT / ? V )
]
worst-case high self-oscillating frequency (570kHz), not
the typical operating frequency of 500kHz. Caution should
be used when synchronizing above 662kHz because at
higher sync frequencies the amplitude of the internal slope
compensation used to prevent subharmonic switching is
sn3431 3431fs
16
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LT3433EFE#PBF 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP 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
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