max9723aebe Maxim Integrated Products, Inc., max9723aebe Datasheet - Page 19

• Manufacturer Part Number: max9723aebe
• Description: Max9723 Stereo Directdrive Headphone Amplifier With Bassmax, Volume Control, And I?c
• Manufacturer: Maxim Integrated Products, Inc.

Figure 12. Using BassMax to Increase MAX9723’s Maximum
Gain
Table 12. BassMax Gain Examples
(R1 = 47kΩ)
Table 13. BassMax Pole and Zero
Examples for a Gain Boost of 8.8dB
(R1 = 47kΩ, R2 = 22kΩ)
C3 (nF)
100
AUDIO
82
68
56
47
22
10
INPUT
R2 (kΩ)
39
33
27
22
15
10
MAX9723
BassMax
R
ENABLE
______________________________________________________________________________________
Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I
f
POLE
174
384
38
47
56
68
81
(Hz)
R
A
OUT_
BB_
V
GAIN (dB)
20.6
15.1
11.3
8.8
5.7
3.7
f
ZERO
1060
106
130
156
190
230
490
CA
RA
RB
(Hz)
interest are not attenuated. For a typical application, set
f
Figure 13 shows the frequency response of the circuit
in Figure 12. With RA = 47kΩ, RB = 22kΩ, and CA =
0.33µF, the passband gain is set to 8.8dB.
Proper layout and grounding are essential for optimum
performance. Connect PGND and SGND together at a
single point on the PC board. Connect PV
and bypass with a 1µF capacitor to PGND. Bypass V
to PGND with a 1µF capacitor. Place the power-supply
bypass capacitor and the charge-pump capacitors as
close to the MAX9723 as possible. Route PGND and all
traces that carry switching transients away from SGND
and the audio signal path. Route digital signal traces
away from the audio signal path. Make traces perpen-
dicular to each other when routing digital signals over
or under audio signals.
The thin QFN package features an exposed paddle
that improves thermal efficiency. Ensure that the
exposed paddle is electrically isolated from PGND,
SGND, and V
SV
exposed paddle cannot be left floating.
Figure 13. Increasing the Maximum Gain Using BassMax
POLE
SS
equal to or below 20Hz.
when the board layout dictates that the
10
9
8
7
6
5
4
3
2
1
0
CA
0.1
FREQUENCY RESPONSE OF FIGURE 12
DD
=
. Connect the exposed paddle to
1
2 π
FREQUENCY (Hz)
f
POLE
10
Layout and Grounding
1
100
×
MAX9723A
CMD REGISTER
CODE = 0xFF
RA = 47kΩ
RB = 22kΩ
CA = 0.33µF
(
RA RB
1k
−
)
10k
SS
to SV
2
C
DD
19
SS