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© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 13
FPF2300/02/03 — Dual-Output Current Limit Switch
Application Information
Figure 38. Self Powered 4-Port USB Hub Using a Single FPF230X
FPF230X is designed to simplify USB port power design based
on self-powering USB host/hub applications. A self-powering
USB port is powered by a local 5V power supply, not by an
upstream port. Each port should supply at least 500mA to each
downstream function based on USB 2.0 specification. Imple-
mentation can depend on the number of USB ports and current
capability per port required in actual power designs. FPF230X
has 1.1A minimum current limit per output, which can cover two
ports, as shown in Figure 38. Four USB ports can be imple-
mented with a single FPF230X part and current limiting is pro-
vided based on a two-port basis for a cost-effective solution.
Figure 39. Individual Port Power Management for Self-Powered 4-Port USB Hub
In Figure 39, each USB port is connected with each output.
Four USB ports can be implemented with two FPF230X parts.
Current limiting and control are provided based on a single port.
Current capability per port has more headroom; up to a mini-
mum of 1.1A per port.
OFF ON ONA
IN
GND
FPF2300/2/3
FLAGB(B)
OUTA
FLAGB(A)
OFF ON ONB OUTB
Host
5V
Downstream
USB Port
Downstream
USB Port
Downstream
USB Port
Downstream
USB Port
1μF
33μF
33μF
33μF
33μF
10KΩ
10KΩ
OFF ON ONA
IN
GND
FPF2300/2/3
FLAGB(B)
OUTA
FLAGB(A)
OFF ON ONB OUTB
Host
5V
Downstream
USB Port
Downstream
USB Port
1μF
33μF
33μF
10KΩ
10KΩ
OFF ON ONA
IN
GND
FPF2300/2/3
FLAGB(B)
OUTA
FLAGB(A)
OFF ON ONB OUTB
Downstream
USB Port
Downstream
USB Port
1μF
33μF
33μF
10KΩ
10KΩ