CM3512 Datasheet, PDF (1/11 Pages) California Micro Devices Corp – Dual USB Overcurrent 1.2A Switches with Independent Controls

CALIFORNIA MICRO DEVICES
Preliminary
CM3512
Dual USB Overcurrent 1.2A Switches with Independent Controls
Features
• Dual switches, each with independent over-current
protection and flag indicator, for 4 USB ports
• Two active low Enable controls, one per output
• Up to 1.2A continuous current each output
• Over-current limits at 1.2A min
• 10msec min fault blanking delay on OC# outputs
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
Applications
The CM3512 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.
Pin Diagram _GND
V_CC
EN1#
TOP
SOIC-8
OC1#
V_OUT1
V_OUT2
• PC’s, Notebooks, STBs
EN2#
OC2#
Product Description
Typical Application Circuit
California Micro Devices CM3512 is a dual channel
USB overcurrent power switch that provides 5V
power to four independent USB ports. The device
has two power switches that provide the V_BUS
voltage at each USB output port with minimal
GND
voltage drop.
When either of the EN# inputs is at logic low, the
V_CC
V_CC
corresponding power switch is ON and V_CC is
connected to the corresponding output through the
EN1#
switch. When either of the EN# inputs is at logic
high, the corresponding power switch is OFF, and
EN2#
no power is available at the output.
OC1#
V_OUT1
V_BUS
V_OUT2
OC2#
V_BUS
2 USB Ports
2 USB Ports
Both of the power switches have full over-current
protection. Whenever the current limit out of either
switch is exceeded, the device enters a constant-
current mode, and the output voltage is
progressively reduced to prevent the current from
increasing further. Each switch is independent of the
other, so if a switch is on but is not in overcurrent
mode then it will remain switched on. The OC#
output becomes active low only if the overcurrent
condition exceeds a minimum continuous duration of
10ms. This fault blanking delay prevents false
alarms 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 that
switch will be turned off and the device temperature
cools down. At T_MIN the switch then turns on again,
and the device heats up again to T_MAX, and so on,
until the fault is removed.
Simplified Electrical Schematic
EN1#
EN2#
V_CC
Charge
Pump
Charge
Pump
Over
current
protect
Over
current
protect
OC1#
V_OUT1
V_OUT2
OC2#
© 2003 California Micro Devices Corp. All rights reserved.
11/10/03 430 N. McCarthy Blvd, Milpitas, California 95035
Tel: [phone]
Fax: [phone]
www.calmicro.com
C0970500
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