参数资料
| 型号： | LT4351IMS#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/20页 |
| 文件大小： | 0K |
| 描述： | IC CTLR MOSFET DIODE-OR 10MSOP |
| 标准包装： | 50 |
| 应用： | 并行/冗余电源 |
| FET 型： | N 沟道 |
| 输出数： | 1 |
| 内部开关： | 无 |
| 延迟时间 - 关闭： | 600ns |
| 电源电压： | 1.2 V ~ 18 V |
| 电流 - 电源： | 1.4mA |
| 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） |
| 供应商设备封装： | 10-MSOP |
| 包装： | 管件 |
| 产品目录页面： | 1338 (CN2011-ZH PDF) |
LT4351
APPLICATIONS INFORMATION
UV HYST
V UV –
? V OV
OV FAULT
V OV ? UV FAULT
OV FAULT ? ( UV FAULT – V UV )
D1
V DD
V UV = 0.33V
BY V IN – V OUT
Inthatcase,theresistorvaluesaresetby:
R3 =
I UVHYST
UV FAULT
R2 = ? R3
UV FAULT – V UV
R1 = ? R3
Hysteresis helps prevent erratic behavior due to the noise
on V IN . Two of the most common noise sources are: V IN
dipping when the MOSFETs first turn on and draw down
the voltage on the V IN capacitors, and the boost regulator
switch turning on and drawing current from the V IN ca-
pacitors. Use low ESR capacitors for V IN and OUT filtering.
Note that because the UV pin uses current hysteresis,
placing a capacitor on UV to ground to filter noise will
reduce the effective hysteresis. Filtering can be achieved
by splitting the R2 resistor, as shown in Figure 4.
To defeat undervoltage fault detection, the UV pin should
be tied higher than 0.33V. UV can be tied to V IN provided
V IN < 9V. Overvoltage fault detection can be defeated by
grounding the OV pin. Do not exceed V IN .
INPUT OV UV
REFERRED REFERRED REFERRED
OVERVOLTAGE FAULT:
GATE LOW
OVERVOLTAGE FILTERED FAULT
OV FAULT V UV = 0.3V
GATE CONTROLLED
V OV > 0.3V V UV < 0.3V
UV FAULT + UV HYST
UNDERVOLTAGE HYSTERESIS
UV FAULT V OV = 0.3V
UNDERVOLTAGE FAULT:
GATE LOW
4351 F05
Boost Regulator
The boost regulator will start working as soon as V IN is
greater than 0.85V. The regulator will supply all the cur-
rent for the gate drive amplifier. While the amplifier itself
requires only about 3mA, larger current pulses are required
when charging the MOSFET gate. The reservoir capacitor
on V DD will provide this current (Figure 6).
V IN
L1
LT4351
SW
QSW
D2 C DD
GND
4351 F06
Figure 6
The regulator performance is relatively insensitive to the
inductor value. The inductor value does control the fre-
quency of operation. A 4.7μH inductor is recommended
for V IN voltages less than 10V and 10μH for V IN voltages
greater than 10V. Several inductors that work well with
the LT4351 are listed in Table 1. Many different sizes and
shapes are available. Consult each manufacturer for more
detailed information and for their entire selection of related
parts. The switching frequency for the boost regulator is
around 1MHz so ferrite core inductors should be used
to obtain the best efficiency. The inductor must handle a
peak current of 0.7A minimum and have a DC resistance
of 0.5Ω or less. Shielded inductors are recommended to
reduce the noise due to inductive switching.
Table 1. Recommended Inductors
PART NUMBER IND (μH) DCR (mΩ) VENDOR
Figure 5. Graphical Representation of the UV and OV Functions
External Shutdown
To externally turn off the MOSFETs, such as to disable the
supply, use an open-collector transistor pulling down on
the UV pin. Note this will not turn off the boost regulator
which will continue to operate.
LPS3314-472ML
LPS4012-103ML
744029004
744042100
SD3112-4R7-R
SD3118-100-R
4.7
10
4.7
10
4.7
10
175
350
200
150
246
295
Coilcraft
847-639-6400
www.coilcraft.com
Würth Elektronik
www.we-online.com
Coiltronics
www.coiltronics.com
4351fd
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT4352 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage Surge |
| LT4356 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage Surge |
| LT4356-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Overvoltage Protection Regulator and Inrush Limiter |
| LT4356-2 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Surge Stopper with Ideal Diode n Adjustable Output Clamp Voltage |
| LT4356-3 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Surge Stopper with Fault Latchoff |
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