MAX9729 Maxim Integrated Products, MAX9729 Datasheet - Page 10

• Manufacturer Part Number: MAX9729
• Description: Stereo Headphone Amplifier
• Manufacturer: Maxim Integrated Products

The MAX9729 stereo headphone amplifier features
Maxim’s patented DirectDrive architecture, eliminating
the large output-coupling capacitors required by con-
ventional single-supply headphone amplifiers. The
MAX9729 consists of two 52mW Class AB headphone
amplifiers, 3:1 stereo input multiplexer/mixer, two
adjustable gain preamplifiers, a dedicated beep ampli-
fier with independent gain control, hardware/software
shutdown control, inverting charge pump, integrated
32-level volume control, BassMax circuitry, comprehen-
sive click-and-pop suppression circuitry, and an
I
Diagram/Typical Operating Circuit ). A negative power
supply (PV
tive supply (PV
and PV
to almost twice that of other single-supply amplifiers,
increasing the total available output power.
An I
munication between the MAX9729 and a microcon-
Stereo Headphone Amplifier with BassMax,
Volume Control, and Input Mux
10
2
C/SMBus-compatible interface (see the Functional
PIN
2
16
17
18
19
20
21
23
24
25
26
27
28
EP
______________________________________________________________________________________
C/SMBus-compatible interface allows serial com-
SS
increases the dynamic range of the amplifiers
SS
BEEP_EN
) is created internally by inverting the posi-
NAME
SHDN
OUTR
OUTL
BEEP
BMR
INR1
BML
INL1
INL2
INL3
V
DD
EP
DD
). Powering the amplifiers from V
Detailed Description
Right BassMax Input. Connect an external passive network between OUTR and BMR to apply bass
boost to the right-channel output. See the BassMax Gain-Setting Components section. Connect BMR to
SGND if BassMax is not used.
Right Headphone Output
Left Headphone Output
Left BassMax Input. Connect an external passive network between OUTL and BML to apply bass boost
to the left-channel output. See the BassMax Gain-Setting Components section. Connect BML to SGND,
if BassMax is not used.
Beep Enable Input. Connect BEEP_EN to PV
beep amplifier.
Active-Low Shutdown Input. Drive SHDN low to disable the MAX9729. Connect SHDN to V
in command register 0x00 is equal to 1 for normal operation (see Command Registers section).
Power-Supply Input. Bypass V
are internally connected and should each have a 1µF bypass capacitor located as to close to the
device as possible.
Beep Input
Left-Channel Input 1
Left-Channel Input 2
Left-Channel Input 3
Right-Channel Input 1
Exposed Paddle. Connect EP to SV
DD
to PGND with a 1µF capacitor and connect to PV
DD
SS
or leave unconnected.
troller. The MAX9729’s slave address is programmed to
one of two different values using the ADD input allowing
two MAX9729 ICs to share the same bus (see Table 1).
The internal command registers control the shutdown
mode of the MAX9729, select/mix input signal sources,
enable the BassMax circuitry, headphone and beep
amplifier gains, and set the volume level (see Table 2).
The MAX9729’s BassMax circuitry improves audio
reproduction by boosting the bass response of the
amplifier, compensating for any low-frequency attenua-
tion introduced by the headphone. External compo-
nents set the MAX9729’s overall gain allowing for
custom gain settings (see the BassMax Gain-Setting
Components section).
Traditional single-supply headphone amplifiers have
their outputs biased about a nominal DC voltage, typi-
cally half the supply, for maximum dynamic range.
Large coupling capacitors are needed to block this DC
bias from the headphone. Without these capacitors, a
significant amount of DC current flows to the head-
DD
FUNCTION
to enable the beep amplifier or to PGND to disable the
Pin Description (continued)
DD
. V
DD
DD
DirectDrive
and PV
while B7
DD