Evaluation Kit Hardware
SAM3S-EK Development Board User Guide
4-9
11031A–ATARM–14-Dec-09
4.3.10
Audio Interface
The SAM3S–EK board supports both audio recording and playback.
The audio volume can be adjusted using the potentiometer RV1, and the microphone amplifier gain can
be adjusted via jumpers (fixed gain of 24 or 26 dB).
4.3.10.1 Microphone Input
The embedded microphone is connected to an audio pre-amplifier using the TS922 operational amplifier
(MN11). The gain is set by using JP14 and JP15 jumpers; both must be set or removed at the same
time.
By modifying the jumper positions, you can select each of the following gain values:
20 dB (default setting, both JP14 and JP15 are off)
26 dB (both JP14 and JP15 are on).
Note:
1.
The TB1 series 0 Ohm resistor is a reservation for future impedance adaptation facility.
Under specific amplifier settings conditions, this enables the easy insertion of a capaci-
tor or any other bipolar device on the audio path. On the other hand, R83 is a default
0 Ohm resistor that enables the disconnection of PB0 from the audio input path for cus-
tom usage.
2.
The audio pre-amplifier MN11 is powered by a dedicated low dropout regulator
MIC5219-3.3 (MN14).
Figure 4-12.
Microphone Input
4.3.10.2 Headphone Output
The SAM3S-EK evaluation kit supports mono/stereo audio playback driven by a TPA0223 audio ampli-
fier connected to two DAC channels of the microcontroller.
The TPA0223 is a 2W mono Bridge-Tied-Load (BTL) amplifier designed to drive speakers with as low as
4 Ohm impedance. The amplifier can be reconfigured on the fly to drive two stereo Single-Ended (SE)
signals into head phones.
JP14 and JP15 should be set
or removed together
AGND
AGND
AGND
AVDD
AGND
AGND
AGND
AVDD
AGND
AGND
DGND
AVDD
AGND
VCC
33
PB0
C72
1nF
C72
1nF
R
8
0
1K
R
8
0
1K
R90
100K
R90
100K
C67
1
u
F
C67
1
u
F
C74
100nF
C74
100nF
R
8
4
1K
R
8
4
1K
R
8
7
47K
R
8
7
47K
R79
1K
R79
1K
R7
8
1K
R7
8
1K
R77
470R
R77
470R
B2
BN0
3
K
3
14
S3
00R
B2
BN0
3
K
3
14
S3
00R
C71
22nF
C71
22nF
R
83
0R
R
83
0R
R
88
470R
R
88
470R
TB1
0R
TB1
0R
C6
3
22
u
F
C6
3
22
u
F
C62
100pF
C62
100pF
C77
4.7
u
F
C77
4.7
u
F
R
8
5
1K
R
8
5
1K
C7
3
22
u
F
C7
3
22
u
F
R75
47K
R75
47K
MN11
T
S
922
MN11
T
S
922
IN1-
2
IN1+
3
OUT2
7
IN2-
6
IN2+
5
GND
4
VCC
8
OUT1
1
JP14
JP14
R76
47K
R76
47K
R9
3
100K
R9
3
100K
R91
0R
R91
0R
JP15
JP15
C69
1nF
C69
1nF
R
8
6
47K
R
8
6
47K
R
8
2
1K
R
8
2
1K
C6
8
1
u
F
C6
8
1
u
F
MIC1
S
VB6050
MIC1
S
VB6050
1
2
R
8
1
100R
R
8
1
100R
