Rainbow Electronics MAX9712 - Manual (Page 13)

MAX9712
500mW, Low EMI, Filterless,
Class D Audio Amplifier
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tered output drives the SYNC input of the slave device
(U2), synchronizing the switching frequencies of the two
devices. Synchronizing two MAX9712s ensures that no
beat frequencies occur within the audio spectrum. This
configuration works when the master device is in either
FFM or SSM mode. There is excellent THD+N perfor-
mance and minimal crosstalk between devices due to
the SYNC connection (Figures 8 and 9). U2 locks onto
only the frequency present at SYNC, not the pulse
width. The internal feedback loop of device U2 ensures
that the audio component of U1’s output is rejected.
UCSP Applications Information
For the latest application details on UCSP construction,
dimensions, tape carrier information, printed circuit
board techniques, bump-pad layout, and recommend-
ed reflow temperature profile, as well as the latest
information on reliability testing results, refer to the
Application Note: UCSP—A Wafer-Level Chip-Scale
Package available on Maxim’s website at www.maxim-
ic.com/ucsp.
Chip Information
TRANSISTOR COUNT: 3595
PROCESS: BiCMOS
Figure 7. Master-Slave Stereo Configuration
IN+
IN-
OUT+
OUT-
SYNC
1 µF
RIGHT-CHANNEL
DIFFERENTIAL
AUDIO INPUT
MAX9712
V DD
V DD PV DD
IN+
IN-
OUT+
OUT-
SYNC
1 µF
LEFT-CHANNEL
DIFFERENTIAL
AUDIO INPUT
MAX9712
V DD PV DD
Figure 8. Master-Slave THD
100
0 0.1 0.2 0.3 0.4 0.5
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
OUTPUT POWER (W)
THD+N (%)
V DD = 3.3V
f = 1kHz
R
L = 8 Ω
SLAVE DEVICE
Figure 9. Master-Slave Crosstalk
0
-120
-100
10 100 1k 10k 100k
CROSSTALK vs. FREQUENCY
-80
FREQUENCY (Hz)
CROSSTALK (dB)
-60
-40
-20
MASTER-TO-SLAVE
SLAVE-TO-MASTER
V DD = 3.3V
R L = 8 Ω
f = 1kHz
V
IN = 500mV P-P