MAX97002 Evaluation Kit
(unchecked), the ZCD forces all volume adjustment to
be made when the output signal is crossing zero, thus
reducing audio clicks during volume changes.
Software Startup
Upon starting the program, the MAX97002 EV kit software
automatically searches for the USB interface circuit and
then for the MAX97002 device address. The MAX97002
EV kit enters the normal operating mode when the
USB connection is detected and has found the device
address. If the USB connection is not detected, the soft-
ware prompts the user to retry or enter the demo mode.
Input Gain
The MAX97002 EV kit software’s Input Gain group box
selects the input channel preamp gain for the MAX97002.
The MAX97002 input channel preamp gain is selectable
among -6dB, -3dB, 0dB, +3dB, +6dB, +9dB, and +18dB.
Demo Mode
The MAX97002 EV kit software enters the demo mode
when the USB connection is not detected, or by select-
ing the Options | Demo Mode menu item in the main
window. When in demo mode, all software communica-
tion to the EV kit circuit is disabled; however, most of the
software GUI is functional. Demo mode allows the user
to evaluate the software without hardware connectivity.
If the USB cable is connected to the EV kit, but power
is not applied to PVDD, the EV kit GUI acts like it is in
demo mode. In such a case, the EV kit is connected to
the PC through USB and I2C commands can be sent to
the MAX97002, but without power, the MAX97002 does
not acknowledge the I2C commands. When power is
applied, press the Reset button to detect the presence
of the MAX97002.
Charge Pump
The MAX97002 features an internal charge pump for
Maxim’s Class H DirectDrive architecture. The charge
pump can operate in two modes, fixed mode and high-
efficiency mode. By default, the MAX97002 charge pump
operates in high-efficiency mode. High-efficiency mode
on the charge pump dynamically changes the internal
supply rails. To have fixed internal supply rails, check the
Fixed Mode checkbox in the Charge Pump group box.
Within fixed mode, there are two options for the supply
rails shown in the drop-down list, 1.8V and 0.9V.
Distortion Limiter
The distortion limiter limits distortion based on the defined
THD level and has programmable release time.
Switch Enable
The MAX97002 features an internal switch that can bypass
the Class D amplifier and allow an external amplifier to
power the same speaker connected to the MAX97002 EV
kit without requiring external switches. Connect the exter-
nal amplifier output to COM1 and COM2, and enable in
the software by checking the Switch Closed checkbox
in the Analog Switch group box.
Write All/Read All/Reset
The Write All button writes the current settings to all of
the registers on the GUI. The EV kit software GUI per-
forms I2C write commands as changes occur on the GUI.
The Read All button changes the GUI settings to match
the MAX97002 register settings. To change settings one
time, enter demo mode by selecting the Options | Demo
Mode menu item, change the GUI to the required settings,
exit demo mode by selecting Options | Demo Mode, and
then press the Write All button. If further changes are not
required, enter demo mode to disable communication to
the MAX97002. To obtain the MAX97002 settings, exit
demo mode and press the Read All button. The Reset
button clears the EV kit software GUI and reprograms the
MAX97002 to default values.
Low-Power Mode
The MAX97002’s low-power mode minimizes current con-
sumption when only using the headphone amplifier. Low-
power mode transmits a single-ended audio signal to the
headphone amplifier from either INA or INB, or a differ-
ential signal from INA and INB. Low-power mode can be
enabled by selecting LP Mode from the drop-down list.
The volume control and mixer are bypassed in this mode.
MAX97002 Master Controls
The EV kit software’s MAX97002 Master Controls group
box contains ENABLE, Volume Slew Disable, and Zero
Crossing Detection Disable checkboxes. The ENABLE
checkbox, which is also called the software shutdown,
enables or disables the MAX97002. The Volume Slew
Disable checkbox, when checked, disables the volume
slewing. The Zero Crossing Detection Disable check-
box disables the zero-crossing detection (ZCD) during a
volume change operation when checked. When enabled
Mixer
The speaker, left headphone, and right headphone
each have an independent mixer. The MAX97002 EV kit
accepts a pair of single-ended audio inputs for stereo
operation, or a pair of differential audio inputs for mono
operation. The single-ended input signals for the speaker
and headphones are defined as IN_1 (left) and IN_2
(right). In the Input Configuration group box, select
Stereo (S/E) for single-ended stereo operation or Mono
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