MIC2012
Micrel
MIC2012/MIC2072
USB Power Controller
General Description
The MIC2012 is a dual channel USB power switch designed to
support the power distribution requirements for USB Wakeup
from the ACPI S3 state. The MIC2012 will directly switch its
two outputs between a 5V main supply and a 5V auxiliary
supply normally provided in ATX style power supplies.
The MIC2012 will adjust its current-limit threshold according
to the ACPI state it is in. In the normal active S0 state the cur-
rent-limit is set at 500mA minimum per channel satisfying the
USB continuous output current specification. In the S3 state
the current-limit can be reduced to only 100mA per channel
to minimize the current that is supplied by the auxiliary supply
thereby ensuring that voltage regulation is maintained even
during fault conditions.
The MIC2012 provides make-before-break switching to ensure
glitch-free transitions between the S3 and S0 states. Each
channel is also thermally isolated from the other so that a
fault in one channel does not effect the other. FAULT status
output signals are also provided indicating overcurrent and
thermal shutdown conditions.
The MIC2072 option latches the output off upon detecting
an overcurrent condition for more than 5ms minimum. The
output can be reset by either toggling the EN inputs of the
MIC2072-1, -2 or by removing the load. Latching the output
off provides a circuit breaker mode of operation which reduces
power consumption during fault conditions.
Features
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Compliant to USB power distribution specifications
UL Recognized Component
Two completely independent switches
Integrated switching matrix supports ACPI S0/S3 state
transitions without external FET circuits
Make-before-break switching ensures glitch-free
transitions
No back-feed of auxiliary supply onto main supply dur-
ing standby mode
Bi-level current-limit preserves auxiliary supply voltage
regulation in standby mode
Thermally isolated channels
Thermal shutdown protection
Fault status outputs with filter prevents false assertions
during hot-plug events
Latched thermal shutdown options with auto-reset
(MIC2072)
Undervoltage lockout
Applications
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Desktop PCs
Notebook PCs
Notebook Docking stations
LAN Servers
PC Motherboards
Typical Application
ATX Power Supply
5V MAIN
5V STANDBY
MIC2012P
MAIN
AUX
S3 Control
S3#
FAULT1#
FAULT2#
GND
100F
82801AA or Equivalent
OUT1
OUT2
100F
V
BUS
D+
D–
GND
Downstream
USB
Port 1
V
BUS
D+
D–
GND
Downstream
USB
Port 2
SLP S3#
SLP S5#
OC0
OC1
Overcurrent Port 1
Overcurrent Port 1
Figure 1. USB Wakeup with Control Input
UL Recognized Component
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
January 2005
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MIC2012/2072
MICREL [ MICREL SEMICONDUCTOR ]
