MAX9879EVKIT+ Maxim Integrated, MAX9879EVKIT+ Datasheet - Page 6

• Manufacturer Part Number: MAX9879EVKIT+
• Description: Audio Amplifiers Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier
• Manufacturer: Maxim Integrated

Specifications of MAX9879EVKIT+

• Product: Class-D
• Output Power: 58 mW, 715 mW
• Thd Plus Noise: 0.04 %
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Power Dissipation: 1250 mW
• Common Mode Rejection Ratio (min): 43 dB
• Input Signal Type: Differential, Single
• Supply Voltage - Max: 5.5 V
• Supply Voltage - Min: 2.7 V

bypass is selected, the left speaker outputs (OUTL+
and OUTL-) are disconnected from the left speaker
amplifier in the MAX9879 and connected to the RXIN+
and RXIN- pins of the MAX9879. This feature allows an
external amplifier connection to the RXIN+ and RXIN-
PCB pads to drive the speaker connected to the
OUTL+ and OUTL- PCB pads of the MAX9879 EV kit.
Check only Right or Left checkboxes to enable just
one speaker amplifier. When only one speaker amplifier
is enabled, stereo input signals are summed to mono
for output on the enabled speaker amplifier.
The Speaker Volume track bar sets the speaker vol-
ume between -99dB (mute) to 0dB (max). Similarly, the
Speaker Volume edit box accepts a numerical value
from -99dB (mute) to 0dB (max) to control the speaker
amplifier volume.
The MAX9879 EV kit software’s Headphone Amplifier
group box contains the Headphone Output group box,
the Left Headphone Volume track bar, Right
Headphone Volume track bar, and the Lock L&R HP
Vol checkbox. The Headphone Output group box
enables or disables headphone outputs. The Left
Headphone Volume and Right Headphone Volume
track bars also have an associated edit box to set the
headphone volume.
Select the Enabled or Disabled radio buttons to enable
or disable the headphone amplifier on the MAX9879 EV
kit.
The Left Headphone Volume and Right Headphone
Volume track bars set the left and right headphone vol-
ume, respectively, to between -99dB (mute) to 0dB
(max). Similarly, the Left Headphone Volume and
Right Headphone Volume edit boxes accept numeri-
cal values from -99dB (mute) to 0dB (max) to control
the left and right headphone volume, respectively.
Check the Lock L&R HP Vol checkbox to lock the Left
Headphone Volume and Right Headphone Volume
track bar. When the Lock L&R HP Vol checkbox is
checked, both Left Headphone Volume and Right
Headphone Volume track bars move simultaneously
when either track bar position is changed.
The MAX9879 EV kit software Registers tab sheet
(Figure 2) displays the data bit logic-level status for
each individual register. A data bit shown in bold indi-
MAX9879 Evaluation Kit
SMBus is a trademark of Intel Corp.
6
_______________________________________________________________________________________
Headphone Amplifier
Registers
cates a logic-high, while nonbolded data bits indicate a
logic-low. Refer to the MAX9879 IC data sheet for
detailed information on the registers and data bits.
There are two methods for communicating with the
MAX9879: through the normal user-interface main win-
dow or through the I
ing Options | Interface (Advanced Users). A display
pops up that allows the SMBus™/I
cols, such as read byte and write byte, to be executed.
The only SMBus/I
MAX9879 are:
• 1: SMBusWriteByte(addr,cmd,data8)
• 4: SMBusReadByte(addr,cmd) → → data8
The combo and edit boxes accept numeric data in
hexadecimal and should be prefixed by 0x. See Figure
3 for an example of this tool.
In this example, the software is writing 0x2F to device
address 1001101(r/w) binary, and register address
0x02.
The MAX9879 EV kit evaluates the MAX9879 stereo
Class D audio subsystem with DirectDrive headphone
amplifiers communicating over a 2-wire I
The Class D audio power amplifier is capable of driving
715mW into an 8Ω speaker. The stereo headphone
amplifier is capable of driving 58mW per channel into a
pair of 16Ω stereo headphones. The EV kit demon-
strates the MAX9879 features such as user-defined
input configuration, input gain, input source, output
enable, and volume control.
The Class D audio power amplifier can be bypassed,
allowing an external amplifier to power the same speak-
er connected to the MAX9879 EV kit without requiring
external switches. Connect the external amplifier output
to the RXIN+, RXIN-, and GND PCB pads on the
MAX9879 EV kit.
The MAX9879 EV kit’s filterless outputs (OUT_+ and
OUT_-) can be connected directly to a speaker load
without any filtering. Use the OUT_+ and OUT_- test
points to connect speaker directly to the MAX9879 out-
puts using twisted-pair cable. Do not install inductors
L1–L4 when operating the EV kit in filterless mode.
Detailed Description of Hardware
2
C-compatible protocols used by the
2
C commands available by select-
Advanced User Interface
External Amplifier
Filterless Output
2
C-compatible proto-
2
C interface.