CALIFORNIA MICRO DEVICES
USB 2.4A Overcurrent Switch
Features
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High-side high current switch with active low Enable
Up to 2.4A continuous current on the output
Over-current limits at 2.4A min
10msec min fault blanking delay on OC# output
prevents false overcurrent alarms
Prevents backdrive current when host powered off
Low operating current (95µA typ.)
Low quiescent current when disabled (<1µA max)
Small 8-Lead SOIC package
Preliminary
CM3513
Pin Diagram
GND
V
CC
V
CC
EN#
TOP
SOIC-8
V
OUT
V
OUT
V
OUT
OC#
Applications
Desktop PCs, Notebooks and Set-Top-Boxes
California Micro Devices’ CM3513 is a USB
overcurrent power switch that provides power to four
USB ports. The device has a power switch that
provides the V
BUS
voltage at the USB output ports
with minimal voltage drop. When the EN# pin is logic
low, the power switch is ON, and V
CC
is connected to
the output V
OUT
. When the EN# pin is logic high, the
power switch is OFF, and no power is available at
the output.
The power switch has full over-current protection.
Whenever the current limit of the switch is
exceeded, the device enters a constant-current
mode, where the output voltage is progressively
reduced to prevent the current from increasing
further. The OC# output becomes active low only if
the overcurrent condition exceeds at least 10ms.
This fault blanking delay prevents false alarms from
being reported to the host USB controller.
If the overcurrent condition is severe enough that
the part heats up to the thermal limit T
MAX
, then the
switch will be turned off and the temperature cools
down. At T
MIN
the switch then turns on again, and
the device heats up again, and so on, until the fault
is removed.
The CM3513 also prevents backdrive current
flowing into the host from the connected peripheral.
This can occur when V
CC
is removed as the host
powers down, and the peripheral still has normal
power applied. The 5V from the peripheral can
therefore be linked to the host’s V
BUS
, potentially
causing backdrive current into the host and
overloading the peripheral power supply.
Product Description
Typical Application Circuit
GND
V
CC
V
CC
V
CC
EN#
V
OUT
V
OUT
V
OUT
OC#
V
BUS
2 USB Ports
2 USB Ports
V
BUS
Simplified Electrical Schematic
EN#
V
CC
Charge
Pump
Over
current
protect
OC#
V
OUT
© 2003 California Micro Devices Corp. All rights reserved.
C0970500
11/10/03
430 N. McCarthy Blvd, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
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CALMIRCO [ CALIFORNIA MICRO DEVICES CORP ]
