Fairchild FPF2300 User Manual

Page 13

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© 2009 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FPF2300/02/03 • Rev. 1.1.3

13

F

P

F2300/02/03 — Dual-Out

put 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

10K

Ω

10K

Ω

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

10K

Ω

10K

Ω

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

10K

Ω

10K

Ω

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