MAX9722AETE Maxim Integrated, MAX9722AETE Datasheet - Page 13
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MAX9722AETE
Manufacturer Part Number
MAX9722AETE
Description
Audio Amplifiers
Manufacturer
Maxim Integrated
Datasheet
1.MAX9722BETE.pdf
(21 pages)
Specifications of MAX9722AETE
Product
General Purpose Audio Amplifiers
Output Power
130 mW
Thd Plus Noise
0.01%
Supply Current
5.5 mA
Maximum Power Dissipation
1176 mW
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Package / Case
TQFN-16
Audio Load Resistance
16 Ohms
Common Mode Rejection Ratio (min)
- 70 dB
Input Offset Voltage
0.5 mV
Minimum Operating Temperature
- 40 C
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Figure 8. Common-Mode Sense Input Eliminates Ground-Loop
Noise
Figure 9. Common-Mode Noise Rejection
AUDIO
AUDIO
INPUT
RIGHT
INPUT
LEFT
Stereo Headphone Amplifiers with Shutdown
SHDN
5V, Differential Input, DirectDrive, 130mW
______________________________________________________________________________________
MAX9722A
EXAMPLE CONNECTION:
IMPROVEMENT FROM
ADDING MAX9722 WITH
SERIES RESISTANCE
V
AUDIO
V
AUDIO
R
2
R
1
RESISTOR IS
INSERTED
BETWEEN THE
JACK SLEEVE
AND
GND = 9.8Ω
MAX9722A
9.8Ω
•
•
•
9.8Ω RESISTOR ADDS TO HP CROSSTALK, BUT DIFFERENTIAL
SENSING AT THE JACK SLEEVE CORRECTS FOR THIS (ONE CHANNEL
ONLY SHOWN).
CURRENT FLOW (IN SIGNAL CABLE SCREEN) DUE TO V
IS GREATLY REDUCED.
NOISE COMPONENT IN THE RECEIVER OUTPUT IS REDUCED BY 34dB
OVER THE PREVIOUS EXAMPLE WITH THE VALUES SHOWN.
•
•
•
V
0.10Ω RESISTANCE FROM CABLE SCREEN.
0.10Ω RESISTANCE DUE TO GND CABLING AT RECEIVER.
V
THE TWO GNDS.
V
0.1Ω
0.1Ω
NOISE
NOISE
NOISE
When the headphone jack is used as a line out to inter-
face between other equipment (notebooks, desktops,
and stereo receivers), potential differences between
the equipment grounds can create ground loops and
excessive ground-current flow. The MAX9722A’s INR+
and INL+ inputs are connected together to form a com-
mon-mode input that senses and corrects for the differ-
ence between the headphone return and device
ground (see Figure 8). Connect INR+ and INL+ through
a resistive voltage-divider between the headphone jack
return and SGND of the device. For optimum common-
mode rejection, use the same value resistors for R
R
and R
capacitor between SGND and R
Application Circuit). If ground sensing is not required,
connect INR+ and INL+ directly to SGND.
Figure 9 shows a theoretical connection between two
devices, for example, a notebook computer (transmit-
ter, on the left) and an amplifier (receiver, on the right),
REPRESENTS THE POTENTIAL DIFFERENCE BETWEEN
F
, and R
F
0.1Ω
0.1Ω
= 30kΩ. Improve DC CMRR by adding a
2
V
V
V
V
and R
REF_IN
REF_IN
IN
IN
= V
= V
Common-Mode Noise Rejection
GND NOISE COMPONENT IN
OUTPUT = V
GND NOISE COMPONENT IN
OUTPUT = V
AUDIO
AUDIO
= V
= (V
NOISE
IN
NOISE
+ (V
. For the MAX9722B, R
/2
NOISE
x 0.99)
NOISE
NOISE
x 0.98)
/2
/100
NOISE
Common-Mode Sense
2
(see the Typical
IN
= 15kΩ
1
and
13