User Manual

Amplifier Gain
The gain of the MAX9820 is set externally using input
and feedback resistors (see the Functional Diagram/
Typical Operating Circuit ). The gain is:
Choose feedback resistor values in the tens of kΩ
range.
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Connect EP and GND together at a single
point on the PCB. Ensure ground return resistance is
minimized for optimum crosstalk performance. Place
the power-supply bypass capacitor, the charge-pump
hold capacitor, and the charge-pump flying capacitor
as close as possible to the MAX9820. Route all traces
that carry switching transients away from the audio sig-
nal path.
A
R
R
VV
V
FB
IN
=− (/ )
MAX9820
DirectDrive Headphone Amplifier
with External Gain
______________________________________________________________________________________ 11
Chip Information
PROCESS: BiCMOS
CHARGE
PUMP
CLICK-AND-POP
SUPPRESSION
C
IN
1.0µF
R
IN
40.2kΩ
R
FB
40.2kΩ
INR
INL
SHDN
GND
TO V
DD
TO V
DD
TO V
SS
OUTL
OUTR
UVLO/SHUTDOWN
CONTROL
C1P
C1N
2.7V TO 5.5V
C3
10µF
C2
1.0µF
C1
1.0µF
V
DD
V
SS
OFF
ON
1
2
8
10
9
3
6
7
4
5
HEADPHONE
JACK
C
IN
1.0µF
R
IN
40.2kΩ
R
FB
40.2kΩ
-1
-1
Functional Diagram/Typical Operating Circuit