US2076_15 Datasheet, PDF (7/8 Pages) Unisonic Technologies – DUAL USB HIGH-SIDE POWER SWITCH

US2076
Preliminary
CMOS IC
„ APPLICATIONS INFORMATION (Cont.)
In Figure 3, the soft start circuit is shown, and the soft start circuit can be utilized to meet USB transient
regulation specifications with large load capacitances (C_BULK >10µF). The device will provide inrush current limiting
for these applications.
V_BUS
USB Hub
GND
Cable
US2076L
1
EN(1)
2 FLG(1)
4.7
µF ³ FLG(2)
4 ^EN(2)
8
OUT(1)
IN ⁷
6
GND
OUT(2) ⁵
USB Peripheral
USB
Controller
C_BULK
USB
Function
USB
Function
C_BULK
Figure 3. Inrush Current-Limit Application
If an inrush current which is from the connection of a heavy capacitive load, the inrush current may cause the
fault flag to fall for a short duration, while the switch is in a constant-current mode, or charging the capacitance. In
that case, to protect this circuit from damage due to erroneous overcurrent reporting, the fault flag circuit can be in
series with a simple 1ms RC low-pass filter (see Figure 4)
Transient Overcurrent Filter _V+
USB Controller
OC
10k
10k
0.1µF
UTC US2076
1 EN/EN(1)
2 _FLG(1)
3 _FLG(2)
4 EN/EN(2)
OUT(1) 8
IN 7
GND 6
OUT(2) 5
Figure 4. Transient Filter
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
7 of 8
QW-R502-446.b