LM3525
Single Port USB Power Switch and Over-Current
Protection
General Description
The LM3525 provides Universal Serial Bus standard power
switch and over-current protection for all host port applica-
tions. The single port device is ideal for Notebook PC and
Handheld PC applications that supply power to one port.
A 1 ms delay on fault flag output prevents erroneous over-
current reporting caused by inrush currents during the
hot-plug events.
The LM3525 accepts an input voltage between 2.7V and
5.5V allowing use as a device-based inrush current limiter
for 3.3V USB peripherals, as well as Root and Self-Powered
Hubs at 5.5V. The Enable input accepts both 3.3V and 5.0V
logic thresholds.
The small size, low R
ON
, and 1 ms fault flag delay make the
LM3525 a good choice for root hubs as well as ganged
power control in space-critical self-powered hubs.
Features
n
1 ms Fault Flag Delay During Hot-Plug Events
n
Smooth Turn-On Eliminates Inrush Induced Voltage
Drop
n
UL Recognized Component: REF # 205202
n
1A Nominal Short Circuit Output Current Protects
Notebook PC Power Supplies
n
Thermal Shutdown Protects Device in Direct Short
Condition
n
500mA Minimum Continuous Load Current
n
Small SO-8 Package Minimizes Board Space
n
2.7V to 5.5V Input Voltage Range
n
Switch Resistance
120 m
Max. at V
IN
= 5V
n
1A Max Standby Current
n
100 A Max Operating Current
n
Undervoltage Lockout (UVLO)
Applications
n
Universal Serial Bus (USB) Root Hubs including
Desktop and Notebook PC
n
USB Monitor Hubs
n
Other Self-Powered USB Hub Devices
n
High Power USB Devices Requiring Inrush Limiting
n
General Purpose High Side Switch Applications
Typical Operating Circuit and Connection Diagram
DS101055-1
DS101055-2
LM3525M-L
DS101055-31
DS101055-30
LM3525M-H
January 2000
LM3525
Single
Port
USB
Power
Switch
and
Over-Current
Protection
2000 National Semiconductor Corporation
DS101055
www.national.com
Ordering Information
Part Number
Enable, Delivery Option
Package Type
LM3525M-H
Active High Enable, 95 units per rail
SO-8,
NS Package
Number M08A
LM3525M-L
Active Low Enable, 95 units per rail
LM3525MX-H
Active High Enable, 2500 units per reel
LM3525MX-L
Active Low Enable, 2500 units per reel
LM3525
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.
Supply Voltage
-0.3V to 6.0V
Output Voltage
-0.3V to 6.0V
Voltage at All Other Pins
-0.3V to 5.5V
Power Dissipation (T
A
= 25C)
(Note 2)
700 mW
T
JMAX
(Note 2)
150C
Operating Ratings
Supply Voltage Range
2.7 to 5.5V
Operating Ambient Range
-40C to +85C
Operating Junction Temperature
Range
-40C to +125C
Storage Temperature Range
-65C to +150C
Lead Temperature
(Soldering, 5 seconds)
260C
ESD Rating (Note 3)
2 kV
DC Electrical Characteristics
Limits in standard typeface are for T
J
= 25C, and limits in boldface type apply over the full operating temperature range. Un-
less otherwise specified: V
IN
= 5.0V, EN = 0V (LM3525-L) or EN = V
IN
(LM3525-H).
Symbol
Parameter
Conditions
Min
Typ
Max
Units
R
ON
On-Resistance
IN to Out pins
V
IN
= 5V
V
IN
= 2.7V
80
120
120
160
m
I
OUT
OUT pins continuous output
current
0.5
A
I
SC
Short Circuit Output Current
(Note 4)
0.5
1.0
1.5
A
I
LEAK
OUT pins Output Leakage
Current
EN = V
IN
(LM3525-L) or
EN = GND (LM3525-H),
0.15
10
A
OC
THRESH
Over-current Threshold
2.25
3.2
A
R
FO
FLAG Output Resistance
I
FO
= 10 mA, V
IN
= 5V
6
25
I
FO
= 10 mA, V
IN
= 2.7V
8
40
I
EN
EN/EN Leakage Current
EN/EN = 0V or EN/EN = V
IN
-0.5
0.5
A
V
IH
EN/EN Input Voltage
(Note 5)
2.4
1.9
V
V
IL
EN/EN Input Voltage
(Note 5)
1.7
0.8
V
V
UVLO
Under-Voltage Lockout
V
IN
= Increasing
V
IN
= Decreasing
1.9
1.8
V
I
DDOFF
Supply Current
Switch OFF
0.05
1
A
I
DDON
Supply Current
Switch ON
65
100
A
Th
SD
Overtemperature Shutdown
Threshold (Note 4)
T
J
Increasing
T
J
Decreasing
135
125
C
C
I
FH
Error Flag Leakage Current
V
FLAG
= 5V
0.1
1
A
LM3525
www.national.com
3
AC Electrical Characteristics
Limits in standard typeface are for T
J
= 25C, and limits in boldface type apply over the full operating temperature range. Un-
less otherwise specified: V
IN
= 5.0V.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
t
r
OUT Rise Time
R
L
= 10
200
s
t
f
OUT Fall Time
R
L
= 10
20
s
t
ON
Turn on Delay, EN to OUT
R
L
= 10
200
s
t
OFF
Turn off Delay, EN to OUT
R
L
= 10
20
s
t
OC
Over Current Flag Delay
R
L
= 0
1
ms
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. Products are not tested under negative Absolute Maximum conditions.
Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
JMAX
(maximum junction temperature),
JA
(junction to am-
bient thermal resistance), and T
A
(ambient temperature). The maximum allowable power dissipation at any temperature is P
DMAX
= (T
JMAX
- T
A
)/
JA
or the number
given in the Absolute Maximum Ratings, which ever is lower. The thermal resistance
JA
of the LM3525 in the SO-8 package is 150C/W.
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 k
resistor into each pin.
Note 4: Thermal shutdown will protect the device from permanent damage.
Note 5: For the LM3525-L, OFF is EN
2.4V and ON is EN
0.8V. For the LM3525-H, OFF is EN
0.8V and ON is EN
2.4V
Pin Description
Pin Number
Pin Name
Pin Function
1
EN
(LM3525-L)
EN
(LM3525-H)
Enable (Input): Logic-compatible enable input.
2
FLG
Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent, UVLO and thermal
shutdown.
3
GND
Ground
4, 5
NC
Not internally connected.
7
IN
Supply Input: This pin is the input to the power switch and the supply voltage for the IC.
6, 8
OUT
Switch Output: This pin is the output of the high side switch. Pins 6 & 8 must be tied together.
Typical Application Circuit
DS101055-3
LM3525
www.national.com
4
Typical Performance Characteristics
V
IN
= 5.0V, I
L
= 500 mA, T
A
= 25C unless otherwise specified.
RDS
ON
vs V
IN
DS101055-4
RDS
ON
vs Temperature
DS101055-5
Current Limit vs Temperature
DS101055-6
Over Current Threshold vs Temperature
DS101055-7
Delay vs Temperature
DS101055-8
UVLO Threshold
DS101055-9
LM3525
www.national.com
5
PDF 
ZIP