MIC2012 Datasheet, PDF (1/10 Pages) Micrel Semiconductor – USB Power Controller Advance Information

MIC2012
MIC2012/MIC2072
USB Power Controller
Advance Information
Micrel
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
current-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 en-
sure 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 re-
duces power consumption during fault conditions.
Features
• Compliant to USB power distribution specifications
• 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
during 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
• Desktop PCs
• Notebook PCs
• Notebook Docking stations
• LAN Servers
• PC Motherboards
Typical Application
ATX Power Supply
5V MAIN
5V STANDBY
82801AA or Equivalent
S3 Control
MIC2012P
MAIN OUT1
AUX
OUT2
S3#
FAULT1#
FAULT2#
GND
100µF
100µF
V_BUS
D+
D–
GND
V_BUS
D+
D–
GND
Downstream
USB
Port 1
Downstream
USB
Port 2
SLP S3#
SLP S5#
OC0
OC1
Overcurrent Port 1
Overcurrent Port 1
Figure 1. USB Wakeup with Control Input
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
September 2000
1
MIC2012/2072