to a common output based on priority and validity. Priority
is defined by pin assignment, with V1 assigned the higher
priority and V2 the lower priority. A power supply is defined
as valid when its voltage has been within its overvoltage
(OV) and undervoltage (UV) window continuously for at
least the configured validation time. If the highest priority
valid input falls out of the OV/UV window, the channel is
immediately disconnected and the other valid input is con-
nected to the common output. Multiple LTC4418s, as well
as triple channel LTC4417s, can be cascaded to provide
switchover between more than two inputs.
The LTC4418 incorporates fast non-overlap switching
circuitry to prevent both reverse and cross conduction
while minimizing output droop. The gate driver includes
a 6V clamp to protect external MOSFETs. A controlled
soft-start feature minimizes start-up inrush current. Open
drain
VALID
outputs indicate the input supplies have been
within their OV/UV window for the duration of the valida-
tion time. The validation time can be disabled or adjusted
using an external capacitor.
Selects Highest Priority Supply from Two Inputs
Blocks Reverse and Cross Conduction Currents
Wide Operating Voltage Range: 2.5V to 40V
–42V Protection Against Reverse Connection
60V Tolerant V1, V2 Inputs
Adjustable Input Validation Time
Fast Switchover Minimizes Output Voltage Droop
Low 26µA Operating Current
±1.5% Input Overvoltage/Undervoltage Protection
Adjustable Overvoltage/Undervoltage Hysteresis
Cascadable for Additional Input Supplies
20-Lead 4mm × 4mm QFN Package
APPLICATIONS
n
n
n
n
Industrial Handheld Instruments
High Availability Systems
Battery Backup Systems
Servers and Computer Peripherals
All registered trademarks and trademarks are the property of their respective owners.
TYPICAL APPLICATION
5V SYS
M1
FDS4465
M2
+
M3
FDS4465
M4
47nF
1.25A MAX OUTPUT
82µF
Priority Switching from V1 to V2
V2
2V/DIV
13.8V
12V WALL
ADAPTER
100nF
470nF
698
BAT46WJ
V1
1M
UV1
60.4k
OV1
226k
V2
1M
UV2
33.2k
OV2
78.7k
VS1
G1
VS2
G2
V
OUT
100k
VALID1
VALID2
100k
V
OUT
5V
V1
2V/DIV
LTC4418
CAS
INTV
CC
EN
SHDN
I
LOAD
= 1.25A
C
OUT
= 82µF
2ms/DIV
4418 TA01b
GND
HYS
255k
TMR
1nF
4418 TA01a
100nF
Document Feedback
For more information
www.analog.com
1
Rev A
LTC4418
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PIN CONFIGURATION
TOP VIEW
SHDN
HYS
Supply Voltages
V1, V2 ..................................................... –42V to 60V
V
OUT
....................................................... –0.3V to 42V
VS1, VS2 ................................................ –0.3V to 60V
Voltage from V1, V2 to V
OUT
....................... –84V to 60V
Voltage from VS1, VS2 to G1, G2 ...............–0.3V to 7.5V
Input Voltages
EN,
SHDN
.............................................. –0.3V to 60V
OV1, OV2, UV1, UV2, TMR....................... –0.3V to 6V
HYS ......................................................... –0.3V to 1V
INTV
CC
.................................................. –0.3V to 6.2V
Output Voltages
VALID1, VALID2
...................................... –0.3V to 60V
CAS.......................................................... –0.3V to 6V
Input Currents
OV1, OV2, UV1, UV2, HYS, TMR,
INTV
CC
, EN,
SHDN
............................................ –3mA
Output Currents
VALID1, VALID2,
CAS .............................. –2mA/+5mA
Operating Ambient Temperature Range
LTC4418C ................................................ 0°C to 70°C
LTC4418I .............................................–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
EN
V1
20 19 18 17 16
TMR 1
UV1 2
OV1 3
UV2 4
OV2 5
6
VALID1
7
VALID2
8
GND
9 10
INTV
CC
CAS
GND
21
15 V
OUT
14 VS1
13 G1
12 VS2
11 G2
UF PACKAGE
20-LEAD (4mm
×
4mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 47°C/W,
θ
JC
= 4.5°C/W
EXPOSED PAD (PIN 21), PCB GND CONNECTION OPTIONAL
ORDER INFORMATION
LEAD FREE FINISH
LTC4418CUF#PBF
LTC4418IUF#PBF
TAPE AND REEL
LTC4418CUF#TRPBF
LTC4418IUF#TRPBF
http://www.linear.com/product/LTC4418#orderinfo
PART MARKING*
4418
4418
PACKAGE DESCRIPTION
20-Lead (4mm × 4mm) Plastic QFN
20-Lead (4mm × 4mm) Plastic QFN
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
Consult ADI Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
V2
2
Rev A
For more information
www.analog.com
LTC4418
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
当今的计算机外部设备，都在追求高速度和高通用性。为了满足用户的需求，以Intel为首的七家公司于1994年推出了USB（Universal Serial Bus，通用串行总线）总线协议，专用于低、中速的计算机外设。目前，USB端口已成为微机主板的标准端口；而在不久的将来，所有的微机外设，包括键盘、鼠标、显示器、打印机、数字相机、扫描仪和游戏柄等等，都将通过USB与主机相连。
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便携式数字数据采集系统（PDDAS）使用了LabVIEW实时模块和PXI，以控制风洞测试和采集记录来自128个不同通道的空气压力数据 "通过LabVIEW实时模块，可以在各种操作情况下获得采集空气压力数据及向风洞提供反馈控制信号所需的确定性响应时间。" – Dave Scheibenhoffer, G Systems 挑战: 用一个可采集、分析和存储来自下一代喷气式战斗机引擎设计的动...[详细]
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