SC2041 Semtech Corporation, SC2041 Datasheet - Page 12

• Manufacturer Part Number: SC2041
• Description: HotSwitch USB Power Distribution Switch With Shutdown
• Manufacturer: Semtech Corporation

July 18, 2000
TYPICAL APPLICATIONS CIRCUITS (Cont.)
Bus-Powered Hub, Ganged-Port Power
Management:
A bus-powered hub distributes power and data from an
input port to downstream ports. It must supply a contin-
uous 100mA of current to each downstream port. A
bus-powered hub must be able to switch power to
downstream ports to prevent illegal device hook-up.
Inrush current limiting is also required to prevent power
supply drooping. The circuit below utilizes the SC2041
to provide ganged port power switching, inrush current
limiting and overcurrent protection for maximum port
protection. In a ganged switch configuration, all ports
are switched simultaneously. Under fault conditions,
Note:
(1) 33µF output capacitor per port meets the USB specification minimum capacitance requirement of 120µF per
hub.
© 2000 SEMTECH CORP.
Upstream Port
VBUS
GND
D+
D-
C1
4.7uF
1
2
U1
1
2
SR05
1
2
3
4
3
U2
SC5205-3.3
VIN
GND
EN BYP
4
3
VO
5
4
C2
10nF
C3
4.7uF
USB Controller
D0D+
D0D-
VCC
D1D+
D2D+
D3D+
D4D+
D1D-
D2D-
D3D-
D4D-
OC
OC
OC
OC
EN
HotSwitch™ USB Power Distribution
Switch With Shutdown
R1 100k
C4
0.1uF
1
2
3
4
U3
GND
IN
IN
SHDN
the USB controller will remove power to all of the
ganged ports. For individual port management,
additional SC2041s may be used.
Since USB is a hot insertion and removal system, USB
ports are subject to electrostatic discharge (ESD). The
SRDA05-4 provides ESD protection on the downstream
data and power lines. Each device will protect two USB
ports. With proper layout the port is hardened to greater
than 15kV, meeting the requirements of IEC 1000-4-2.
On the upstream port, the SR05 provides ESD protec-
tion to the above levels for one line pair. The SC5205
LDO regulator is used to power the hub controller from
the upstream bus.
SC2041
652 MITCHELL ROAD NEWBURY PARK CA 91320
OUT
OUT
OUT
FLG
U4
SRDA05-4
I/O1
I/O2
I/O3
I/O4 REF2
8
7
6
5
U5
SRDA05-4
REF1
REF1
REF2
I/O1
I/O2
I/O3
I/O4 REF2
REF1
REF1
REF2
C5
33uF
C6
33uF
C7
33uF
C8
33uF
SC2041
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Downstream Port
Downstream Port
Downstream Port
Downstream Port
VBUS
D+
D-
GND
VBUS
D+
D-
GND
VBUS
D+
D-
GND
VBUS
D+
D-
GND
12