IMP2526
Application Information
USB
Controller
IMP2526-2
8
7
6
5
1
2
USB
Function
VBUS
USB Hub
GND
ENA
OUTA
IN
FLGA
FLGB
ENB
CBULK
3
4
GND
OUTB
USB
Function
4.7µF
CBULK
Cable
USB Peripheral
2526_07.eps
Figure 3. Inrush Current-Limit Application
V+
Transient Overcurrent Filter
If a heavy capacitive load is suddenly connected to the output, the
switch current-limiting function may cause the fault-flag to go
low for 10µs to 200µs as the switch, in a constant current mode,
charges the capacitance. If this transient over-current fault report-
ing is not wanted, a simple 1ms RC low-pass filter in series with
the fault flag circuit will prevent this momentary flag (Figure 4).
10k
10k
USB Controller
IMP2526
FLG
2
OVERCURRENT
0.1µF
2526_05.eps
Figure 4. Transient Filter
100k
100k
10k
V
5.0V
CC
10k
Ferrite
Beads
Upstream
V
3.3V
USB Controller
BUS
100mA max
VBUS
1
8
7
VBUS
D+
IN OUT
V
ON/OFF
ENA OUTA
IMP2526-2
IN
+
47µF
2
3
D+
OVERCURRENT
OVERCURRENT
FLGA
IN
USB
Port 1
6
5
FLGB
0.1µF
LDO
D–
D–
GND
4
OUTB
ON/OFF
ENB
GND
GND
GND
1µF
1µF
VBUS
D+
Data
USB
Port 2
47µF
+
D–
GND
2526_08.eps
Data
(Two Pair)
Figure 5. Single-Port Self-Powered Hub Application
6
© 2000 IMP, Inc.
6
408-432-9100/www.impweb.com
A1PROS [ A1 PROS CO., LTD. ]
