LM3526 Datasheet, PDF (1/11 Pages) National Semiconductor (TI) – Dual Port USB Power Switch and Over-Current Protection

February 2000
LM3526
Dual Port USB Power Switch and Over-Current
Protection
General Description
The LM3526 provides Universal Serial Bus standard power
switch and over-current protection for all host port applica-
tions. The dual port device is ideal for Notebook and desktop
PC’s that supply power to more than one port.
A 1 ms delay on the fault flag output prevents erroneous
overcurrent reporting caused by in-rush currents during
hot-plug events.
The dual stage thermal protection circuit in the LM3526 pro-
vides individual protection to each switch and the entire de-
vice. In a short-circuit/over-current event, the switch dissipat-
ing excessive heat is turned off, allowing the second switch
to continue to function uninterrupted.
The LM3526 accepts an input voltage between 2.7V and
5.5V allowing use as a device-based in-rush current limiter
for 3.3V USB peripherals, as well as Root and Self-Powered
Hubs at 5.5V. The Enable inputs accept both 3.3V and 5.0V
logic thresholds.
The small size, low R_ON, and 1 ms fault flag delay make the
LM3526 a good choice for root hubs as well as per-port
power control in embedded and stand-alone hubs.
Features
n 1 ms fault flag delay filters Hot-Plug events
n Smooth turn-on eliminates in-rush induced voltage drop
n UL recognized component: REF# 205202
n 1A nominal short circuit output current protects 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 140 mΩ Max. switch resistance
n 1 µA Max. standby current
n 200 µA Max. operating current
n Under-voltage 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 In-rush Limiting
n General Purpose High Side Switch Applications
Typical Operating Circuit and Connection Diagram
DS101097-2
LM3526-H
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© 2000 National Semiconductor Corporation DS101097
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LM3526-L
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