© 2007 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FSA321

• Rev.1.0.6

2

Pin Configuration

GND

1

8

5

4

3

2

D +

D -

R

L

D +/R

D-/L

A/LP Sel

USB Sel

9

10

6

7

Figure 2. UMLP

Pin Definitions

Pin #

Name

Description

9

Power supply

5

A/LP Sel

Audio Select Override and Power-Save Mode. This pin can be used to override USB Sel for

applications where analog audio is transmitted on the USB D+, D- lines. This same select pin is

used to put the FSA321 in low-power mode when USB Sel is LOW, not transmitting audio signals

or USB data. The FSA321 has a weak internal pull-down, setting its default state to LOW and

allowing this pin to float when not in use.

8

USB Sel

10, 1

D+, D-

USB data bus input sources

2, 3

R, L

Audio right and left input sources

7, 6

D+/R, D-/L USB and audio common connector ports

Truth Table

USB Sel

(1)

A/LP Sel

Audio Mode

USB Mode

Remarks

LOW

OFF

OFF

Disabled Inputs High-Z

HIGH

(2)

HIGH

(2)

LOW

OFF

ON

USB Communication

HIGH

(2)

HIGH

(2)

HIGH

(2)

ON

OFF

Audio Override on USB

HIGH

(2)

LOW

HIGH

(2)

OFF

OFF

Low Power Mode

HIGH

(2)

LOW

LOW

ON

OFF

Audio Out

Notes:

1.

2.

(see DC Tables).