Datasheet

MAX9759
3.2W, High-Efficiency, Low-EMI, Filterless,
Class D Audio Amplifier
______________________________________________________________________________________ 15
Component Selection
Input Filter
An input capacitor, C
IN
, in conjunction with the input
impedance of the MAX9759 forms a highpass filter that
removes the DC bias from an incoming signal. The AC-
coupling capacitor allows the amplifier to bias the sig-
nal to an optimum DC level. Assuming zero source
impedance, the -3dB point of the highpass filter is
given by:
f
-3dB
= 1/(2πR
IN
C
IN
)
Choose C
IN
such that f
-3dB
is well below the lowest fre-
quency of interest. Setting f
-3dB
too high affects the
low-frequency response of the amplifier. Use capaci-
tors whose dielectrics have low-voltage coefficients,
such as tantalum or aluminum electrolytic. Capacitors
with high-voltage coefficients, such as ceramics, may
result in increased distortion at low frequencies.
IN+
IN-
OUT+
OUT-
SYNC_OUT
RIGHT-CHANNEL
DIFFERENTIAL
AUDIO INPUT
MAX9759
V
DD
V
DD
PV
DD
IN+
IN-
OUT+
SYNC_OUT
SYNC
LEFT-CHANNEL
DIFFERENTIAL
AUDIO INPUT
MAX9759
V
DD
PV
DD
IN+
IN-
OUT+
SYNC_OUT
SYNC
DIFFERENTIAL
AUDIO INPUT
MAX9759
V
DD
PV
DD
SYNC
U1
U2
Figure 7. Master-Slave Configuration
100
0 0.5 1.0 1.5 2.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
OUTPUT POWER (W)
THD+N (%)
V
DD
= 5.0V
f = 1kHz
R
L
= 8Ω
SLAVE DEVICE
Figure 8. Total Harmonic Distortion Plus Noise vs. Output
Voltage
-150
10 100
1k
100k
CROSSTALK vs. FREQUENCY
-130
-110
-90
-30
FREQUENCY (Hz)
CROSSTALK (dB)
-70
-50
10k
V
DD
= 5V
R
L
= 8Ω
f = 1kHz
MASTER TO SLAVE
SLAVE TO MASTER
Figure 9. Crosstalk vs. Frequency