USB2227 and USB2228 USB2.0 Flash Card Reader Media Power Considerations

SMSC WP 1.5

3

Revision 1.1 (03-31-05)

WHITE PAPER

Figure 3 Output Voltage vs. Load Current for VDDIO = 3.3V

Figure 2 Implementation Using Integrated FETs

USB2227/8

USB2.0

Flash Card

Reader

3.3V

Regulator

CF Card

Power

Control

USB

VBUS

Cin

Cout

Cg

Ccard

Rg

M1

VDD

SM/xD

SD/MMC MS/MSPro

CF

MS Card

Power

SD Card

Power

SM Card

Power

0

0.5

1

1.5

2

2.5

3

3.5

0

50

100

150

200

250

Load Current (mA)

Output Voltage (V)

Vout(V)