For the left channel, capacitor C9 creates a pole and a

zero according to the following equations:

longer affects the transfer function and the volume-control

gain dominates. Table 4 lists capacitor values and the

corresponding poles and zeros for a given DC gain.

See Figure 7 for an example of a gain profile using

BassMax. Set the right-channel frequency response by

adjusting R4, R3, and C10.

MAX9723D EV System

The MAX9723D EV system (MAX9723DEVCMODU+ or

MAX9723DEVCMOD2+) is a complete stereo

DirectDrive headphone amplifier system consisting of

the MAX9723D EV kit and Maxim’s system command

module (CMODUSB+ or CMOD232+).

The MAX9723D EV kit provides a proven layout for

evaluating the MAX9723 and comes with the

MAX9723DETE+ installed.

CMODUSB+ and CMOD232+

Command Module

The CMODUSB+ and CMOD232+ use a proprietary

demonstrate various Maxim devices. Maxim reserves

the right to change the implementation of this module at

any time with no advance notice.

CMODUSB+ Power Supply

The CMODUSB+ board uses a MAX1658 linear regula-

tor. Jumper J1 selects between the 5VDC voltage that

comes from the USB connector and the MAX1658’s

regulated 3.3V output voltage. Set the CMODUSB+

jumper J1 at position 2-3 to have 3.3V output voltage to

evaluate the MAX9723D EV kit.

CMOD232+ Power Supply

The CMOD232+ board uses a MAX1659 linear regula-

tor. Jumper J1 selects either the MAX1659’s 5V default

output voltage or 3.3V output voltage. Set the

CMOD232+ jumper J1 at position 1-2 to have 3.3V out-

put voltage to evaluate the MAX9723D EV kit.

MAX9723D EV Kit Stand-Alone Operation

The MAX9723D EV kit operates without the system

command module, but the functions are limited to

power-on reset-default settings listed below:

•

BassMax enabled

•

Maximum gain range:

0dB for MAX9723A/MAX9723B or +6dB for

MAX9723C/MAX9723D

•

Maximum gain setting

•

Device enabled

Input Mode

The audio input terminals on the MAX9723D EV kit

accept stereo single-ended inputs (INR and INL).

write only. Versions A and C have a fixed slave address

of 1001100X, and versions B and D have a fixed slave

address of 1001101X. See Table 1 for details.

f

RR

CR

R

f

RR

CR

R

POLE

ZERO

=

××

×

=

+

××

×

−

56

2

956

56

2

956

π

π

MAX9723D Evaluation Kit/Evaluation System

6

_______________________________________________________________________________________

C9 (C10) (nF)

100

38

106

82

47

130

68

56

156

56

68

190

47

81

230

22

174

490

10

384

1060

Note: Reference designators in parenthesis indicate right-

channel components. Simply substitute R4 for R5, R3 for R6,

and C10 for C9 for right-channel equations.

Table 4. BassMax Pole and Zero

Examples for a Gain Boost of 8.8dB—R5

(R4) = 47kΩ and R6 (R3) = 22kΩ

SMBus is a trademark of Intel Corp.