March 2001
LM3544
Quad Port USB Power Distribution Switch and
Over-Current Protection
General Description
The LM3544 is a quad high-side power switch that is an excellent choice for use in Root, Self-Powered and Bus-Powered USB (Universal Serial Bus) Hubs. Independent port enables, flag signals to alert USB controllers of error conditions, controlled start-up in hot-plug events, and short circuit protection all satisfy USB requirements.
The LM3544 accepts input voltages between 2.7V and 5.5V. The Enable logic inputs, available in active-high and active-low versions, can be powered off any voltage in the 2.7V to 5.5V range. The LM3544 limits the continuous current through a single port to 1.25A (max.) when it is shorted to ground.
The low on-state resistance of the LM3544 switches ensures the LM3544 will satisfy USB voltage drop requirements, even when current through a switch reaches 500 mA. Thus, High-Powered USB Functions, Low-Powered USB functions, and Bus-Powered USB Hubs can all be powered off a Root or Self-Powered USB Hub containing the LM3544.
Added features of the LM3544 include current foldback to reduce power consumption in current overload conditions, thermal shutdown to prevent device failure caused by high-current overheating, and undervoltage lockout to keep switches from operating if the input voltage is below acceptable levels.
Features
n90mΩ (typ.) High-Side MOSFET Switch
n500mA Continuous Current per Port
n7 ms Fault Flag Delay Filters Hot-Plug Events
nIndustry Standard Pin Order
nShort Circuit Protection with Power-Saving Current Foldback
nThermal Shutdown Protection
nUndervoltage Lockout
nRecognized by UL and Nemko CB
nInput Voltage Range: 2.7V to 5.5V
n5µA Maximum Standby Supply Current
n16-Pin SOIC Package
nAmbient Temperature Range: −40ÊC to 85ÊC
Applications
nUSB Root, Self-Powered, and Bus-Powered Hubs
nUSB Devices such as Monitors and Printers
nGeneral Purpose High Side Switch Applications
10120832
10120833
Functional Diagram
10120801
Protection Current-Over and Switch Distribution Power USB Port Quad LM3544
© 2001 National Semiconductor Corporation |
DS101208 |
www.national.com |
LM3544
Connection Diagrams
LM3544-H |
LM3544-L |
16-Pin SOIC |
16-Pin SOIC |
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10120802 |
10120829 |
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Top View |
Top View |
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Ordering Information |
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Part Number |
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Enable, Delivery Option |
Package Type |
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LM3544M-H |
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Active High Enable |
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LM3544M-L |
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Active Low Enable |
SO-16 |
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NS Package Number M16A |
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LM3544MX-H |
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Active High Enable, 2500 units per reel |
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LM3544MX-L |
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Active Low Enable, 2500 units per reel |
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Typical Application Circuit
10120804
FIGURE 1. The LM3544 used in a Self-Powered or Root USB Hub
www.national.com |
2 |
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications.
Voltage at INX and OUTX pins |
−0.3V to 6V |
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Voltage at ENX |
(EN |
X) and FLAGX |
−0.3V to 5.5V |
pins |
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Power Dissipation (Note 2) |
Internally Limited |
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Maximum Junction Temperature |
150ÊC |
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Storage Temperature Range |
−65ÊC to 150ÊC |
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Lead Temperature Range |
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(Soldering, 5 sec.) |
260ÊC |
ESD Rating (Note 3) |
2 kV |
Operating Ratings
Supply Voltage Range |
2.7V to 5.5V |
Continuous Output Current Range |
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(Each Output) |
0 mA to 500 mA |
Junction Temperature Range |
−40ÊC to 125ÊC |
DC Electrical Characteristics
Limits in standard typeface are for TJ = 25ÊC, and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: VIN = 5.0V, ENX = VIN (LM3544-H) or ENX = 0V (LM3544-L).
Symbol |
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Parameter |
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Conditions |
Min |
Typ |
Max |
Units |
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RON |
On Resistance |
VIN = 5V, IOUTX = 0.5A |
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90 |
125 |
mΩ |
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VIN = 3.3V, IOUTX = 0.5A |
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95 |
130 |
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IOUT |
OUTX Continuous Output |
3.0V ≤ VIN ≤ 5.5V |
0.5 |
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A |
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Current |
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ILEAK-OUT |
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0.01 |
1 |
µA |
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OUTX Leakage Current |
ENX = 0 |
(EN |
X = VIN); |
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TJ = 25ÊC |
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10 |
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ENX = 0 |
(EN |
X = VIN); |
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µA |
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− 40 ≤ TJ ≤ 125ÊC |
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ISC |
OUTX Short-Circuit Current |
OUTX Connected to GND |
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0.8 |
1.25 |
A |
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(Note 4) |
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OCTHRESH |
Overcurrent Threshold |
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2.0 |
3.2 |
A |
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VL_FLAG |
FLAGX Output-Low Voltage |
I(FLAGX) = 10 mA |
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0.1 |
0.3 |
V |
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ILEAK-FLAG |
FLAGX Leakage Current |
2.7 ≤ VFLAG ≤ 5.5V |
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0.2 |
1 |
µA |
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ILEAK-EN |
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−0.5 |
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0.5 |
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ENx Input Leakage Current |
ENx |
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x = 0V or |
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µA |
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ENx |
/EN |
x = VIN |
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VIH |
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2.7V ≤ VIN ≤ 5.5V |
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EN/EN |
Input Logic High |
2.4 |
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V |
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VIL |
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4.5V ≤ VIN ≤ 5.5V |
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EN/EN |
Input Logic Low |
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0.8 |
V |
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2.7V ≤ VIN ≤ 4.5V |
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0.4 |
V |
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VUVLO |
Under-Voltage Lockout |
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1.8 |
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V |
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Threshold |
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375 |
600 |
µA |
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ENx = VIN |
(EN |
x = 0 ); |
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IDDON |
Operational Supply Current |
TJ = 25ÊC |
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800 |
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ENx = VIN (ENx = 0 ); |
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µA |
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−40ÊC ≤ TJ ≤ 125ÊC |
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1 |
µA |
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ENx = 0 |
(EN |
x = VIN); |
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IDDOFF |
Shutdown Supply Current |
TJ = 25ÊC |
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−40ÊC ≤ TJ ≤ 125ÊC |
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5 |
µA |
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Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device beyond its rated operating conditions.
Note 2: The maximum allowable power dissipation is a function of the Maximum Junction Temperature (TJMAX), Junction to Ambient Thermal Resistance (θJA), and
the Ambient Temperature (TA). The LM3544 in the 16-pin SOIC package has a TJMAX of 150ÊC and a θJA of 130ÊC/W. The maximum allowable power dissipation at any temperature is PMAX = (TJMAX − T A)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the part will go into thermal shutdown.
Note 3: The Human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.
Note 4: Thermal Shutdown will protect the device from permanent damage.
LM3544
3 |
www.national.com |
LM3544
AC Electrical Characteristics
Limits are for TJ = 25ÊC and VIN = 5.0V.
Symbol |
Parameter |
Conditions |
Min |
Typ |
Max |
Units |
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tr |
OUTx Rise Time (Note 5) |
CL = 33 µF, ILOAD = 500 mA |
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1.5 |
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ms |
tf |
OUTx Fall Time (Note 6) |
CL = 33 µF, ILOAD = 500 mA |
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0.9 |
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tON |
Turn-on Delay (Note 7) |
CL = 33 µF, ILOAD = 500 mA |
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2.9 |
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ms |
tOFF |
Turn-off Delay (Note 8) |
CL = 33 µF, ILOAD = 500 mA |
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0.7 |
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ms |
tF |
Flag Delay (Note 9) |
IFLAG = 10 mA |
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7 |
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ms |
Note 5: Time for OUTx to rise from 10% to 90% of its enabled steady-state value after ENx (ENx) is asserted.
Note 6: Time for OUTx to fall from 10% to 90% of its enabled steady-state value after ENx (ENx) is deasserted.
Note 7: Time between ENx rising through VIH (ENx falling through VIL) and OUTx rising through 90% of its enabled steady-state voltage.
Note 8: Time between ENx falling through VIL (ENx rising through VIH) and OUTx falling through 10% of its enabled steady-state voltage.
Note 9: Time between ENx rising through VIN (ENx falling through VIN) and FLAGX falling through 0.3V when OUTX is connected to GND.
Pin Description
Pin Number |
Pin Name |
Pin Function |
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2, 6 |
IN 1, 2 |
Supply Inputs: These pins are the inputs to the power switches and the supply |
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input for the IC. In most applications they are connected together externally |
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and to a single input voltage supply. |
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1, 5 |
GND 1, 2 |
Grounds: Must be connected together and to a common ground. |
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15, 14, 11, 10 |
OUT 1, 2, 3, 4 |
Switch Outputs: These pins are the outputs of the high side switches. |
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3, 4, 7, 8 |
LM3544-H: EN 1, 2, 3, 4 |
Enable (Inputs): Active-high (or active-low) logic enable inputs. |
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(LM3544-L: |
EN |
1, 2, 3, 4) |
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16, 13, 12, 9 |
FLAG 1, 2, 3, 4 |
Fault Flag (Outputs): Active-low open drain outputs. Indicates over-current, |
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UVLO or thermal shutdown. See ²Application Information² section for more |
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details. |
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www.national.com |
4 |
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