© 2009 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FSA2000

• Rev. 1.0.0

4

Functional Description

Figure 4. Micro-USB Application

Application Guidelines

– Minimize to USB port & USB TX.

– Minimize and match trace lengths for

USB compliance.

– Suggest 0.1µFcapacitor as close to the

device as possible for DC-blocking and setting low-

frequency response of audio amplifier. The input

capacitors combine with the input impedance of the

amplifiers to form a high-pass filter. Equation 1 can be

used to calculate the -3dB cut-off frequency of the high-

pass filter for the given input capacitor value and the

FSA2000 input impedance.

i

Z

2

1

f

dB

3









(1)

)

1

.

0

)(

90

(

2

1

7

.

17

F

k

Hz









(2)

Users have flexibility to adjust capacitor for audio

performance in the system design. Equation 2 shows the

cut-off frequency of the recommended guidelines.

– Use standard decoupling devices, 0.1µF & 1µF

capacitors; as close to the device as possible.

– Minimize ground trace length between headphone

connector and device; minimize ground path resistance.

– Suggested 0.1µFcapacitor to GND for filtering; as

close to the device as possible.

– Use low-ESR (equivalent series resistance)

ceramic capacitors for lowest charge pump impedance,

which provides maximum output power of the audio

amplifiers. Recommended to place the components as close

as possible to the device.

ESR ceramic capacitors for the flying capacitor between CP

and CM, along with the output capacitors on V+, CPO, and

V-. Optimized values for these capacitors are in Figure 4.

1

5

6

7

8

9

10

11

2

3

12

16

15

14

13

4

V-

V+

+

-

Audio / Click & Pop Control

CP

CM

CPO

V-

V+

V

BUS

D+/R

D-/L

V

CC

MUTE

/SHDN

GND

D+

D-

R

L

V-

V+

+

-

Charge Pump

& Voltage

Regulator

0.1µF

0.1µF

1µF

1µF

1µF

2.2µF

Audio

Subsystem

HS USB TX

2.7

– 4.3V

1µF

0.1µF

C

i

C

i

Z

IN

Z

IN

USB

Port