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參數(shù)資料
| 型號： | LM3543MX-L |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 電源管理 |
| 英文描述： | Triple Port USB Power Distribution Switch and Over-Current Protection |
| 中文描述： | 3-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| 封裝： | SOIC-16 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大?。?/td> | 316K |
| 代理商： | LM3543MX-L |
Functional Description
Power Switches
The power switches that comprise the three ports of the
LM3543 are N-Channel MOSFETs. They have a typical
on-state drain-to-source resistance of 90 m
when the input
voltage is 5 V. When enabled, each switch will supply a 500
mA minimum current to its load. In the unlikely event that a
switch is enabled and the output voltage of that switch is
pulled above the input voltage, the bi-directional nature of
the switch results in current to flow from the output to the
input. When a switch is disabled, current flow through the
switch is prevented in both directions.
Charge Pump and Driver
The gate voltages of the high-side NFET power switches are
supplied by an internal charge-pump and driver circuit
combination.
The
charge
switched-capacitor circuit that efficiently generates voltages
above the LM3543 input supply. The charge pump output is
used to supply a transconductance amplifier driver circuit
that controls the gate voltages of the power switches. Rise
and fall times on the gates are typically kept between 2 ms
and 4 ms to limit large current surges and associated
electromagnetic interference (EMI).
pump
is
a
low-current
ENABLE (EN
x
or EN
x
)
The LM3543 comes in two versions: an active-high enable
version, LM3543-H, and an active-low enable version,
LM3543-L. In the LM3543-H, the EN
x
pins are active-high
logic inputs that, when asserted, turn on the associated
power supply switch(es). Power supply switches are
controlled by the EN
active-low logic inputs in the
LM3543-L. With all three ports disabled on either version of
the LM3543, less than 5 μA of supply current is consumed.
Both types of enable inputs, active-high and active-low, are
TTL and CMOS logic compatible.
Input and Output
The power supply to the control circuitry and the drains of the
power-switch MOSFETs are connected to the two input pins,
IN1 and IN2. These two pins are connected externally in
most standard applications. The two ground nodes GND1
and GND2 must be connected externally in all applications.
Pins OUT1, OUT2, and OUT3 are connections to the source
nodes of the power-switch MOSFETs. In a typical application
circuit, current flows through the switches from IN1 and IN2
to OUT
x
toward the load.
Undervoltage Lockout (UVLO)
Undervoltage Lockout (UVLO) prevents the MOSFET
switches from turning on until the input voltage exceeds a
typical value of 1.8V.
If the input voltage drops below the UVLO threshold, the
MOSFET switches are opened and fault flags are activated.
UVLO flags function only when one or more of the ports is
enabled. Due to the paired nature of the design, both FLAG1
and FLAG2 will assert if either port1 or port2 is enabled in a
UVLO condition.
Current Limit and Foldback
The current limit circuit is designed to protect the system
supply, the LM3543 switches, and the load from potential
damage resulting from excessive currents. If a direct short
occurs on an output of the LM3543, the input capacitor(s)
rapidly discharge through the part, activating current limit
circuitry. The threshold for activating current limiting is 2.0A
(typ.). Protection is achieved by momentarily opening the
MOSFET switch and then gradually turning it on. Turn-on is
halted when the current through the switch reaches the
current-limit level of 1.0A (typ.) The current is held at this
level until either the excessive load/short is removed or the
part overheats and thermal shutdown occurs (see Thermal
Shutdown section, below). The fault flag of a switch is
asserted whenever the switch is current limiting.
If a port on the LM3543 is enabled into a short condition, the
output current of that port will rise to the current-limit level
and hold there.
When a port is in a current-limit condition, the LM3543
senses the output voltage on that port and, if it is less than
1.0V (typ.), will reduce the output current through that port.
This operation is shown in Figure 2 below. The current
reduction, or foldback, reduces power dissipation through
the overloaded MOSFET switch. An additional advantage of
the foldback feature is the reduction of power required from
the source supply when one or more output ports are
shorted.
Thermal Shutdown
The LM3543 is internally protected against excessive power
dissipation by a two-stage thermal protection circuit. If the
device temperature rises to approximately 145C, the
thermal shutdown circuitry turns off any switch that is current
limited. Non-overloaded switches continue to function
normally. If the die temperature rises above 160C, all
switches are turned off and all three fault flag outputs are
activated. Hysteresis ensures that a switch turned off by
thermal shutdown will not be turned on again until the die
temperature is reduced to 135C. Shorted switches will
continue to cycle off and on, due to the rising and falling die
temperature, until the short is removed.
The thermal shutdown function is shown graphically in
Figure 3 and Figure 4
10125817
FIGURE 2. Short-Circuit Output Current (with
Foldback) vs. Output Voltage
L
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相關PDF資料 |
PDF描述 |
|---|---|
| LM3543 | Triple Port USB Power Distribution Switch and Over-Current Protection |
| LM3544M-H | Quad Port USB Power Distribution Switch and Over-Current Protection |
| LM3544M-L | Backplane/Data Transfer Connector; No. of Contacts:50; No. of Rows:2; Mounting Type:PCB Straight Thru Hole; Contact Plating:Gold; Current Rating:2A; Gender:Female; Leaded Process Compatible:Yes RoHS Compliant: Yes |
| LM3544MX-H | Quad Port USB Power Distribution Switch and Over-Current Protection |
| LM3544MX-L | Quad Port USB Power Distribution Switch and Over-Current Protection |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3543MX-L/NOPB | 制造商:Texas Instruments 功能描述:USB Power SW Hi Side/DIST Triple 5.5V 2A 16-Pin SOIC N T/R |
| LM3544 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Quad Port USB Power Distribution Switch and Over-Current Protection |
| LM3544B-H E WAF | 制造商:Texas Instruments 功能描述: |
| LM3544M-H | 制造商:Texas Instruments 功能描述:2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| LM3544M-H/NOPB | 功能描述:IC USB QUAD PORT SWITCH 16-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電源分配開關 系列:- 特色產品:XRP252 Switches 標準包裝:1 系列:- 類型:高端開關 輸出數(shù):2 Rds（開）:140 毫歐 內部開關:是 電流限制:1.15A 輸入電壓:1.75 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-WFDFN 裸露焊盤 供應商設備封裝:10-TDFN（3x3） 包裝:Digi-Reel® 其它名稱:1016-1691-6 |
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