MAX9722AETE+G Maxim Integrated Products, MAX9722AETE+G Datasheet - Page 8

• Manufacturer Part Number: MAX9722AETE+G
• Description: IC AMP AUDIO .13W STER AB 16TQFN
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive™r
• Type: Class ABr

Specifications of MAX9722AETE+G

• Output Type: Headphones, 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 130mW x 2 @ 32 Ohm
• Voltage - Supply: 2.4 V ~ 5.5 V
• Features: Depop, Differential Inputs, Short-Circuit and Thermal Protection, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 16-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MAX9722AETE+G47; MAX9722AETE+G47

5V, Differential Input, DirectDrive, 130mW
Stereo Headphone Amplifiers with Shutdown
The MAX9722A/MAX9722B stereo headphone amplifiers
feature Maxim’s DirectDrive architecture, eliminating the
large output-coupling capacitors required by conven-
tional single-supply headphone amplifiers. The devices
consist of two class AB headphone amplifiers, undervolt-
age lockout (UVLO)/shutdown control, charge pump,
and comprehensive click-and-pop suppression circuitry
(see Typical Application Circuit). The charge pump
inverts the positive supply (PV
supply (PV
these bipolar supplies with their outputs biased about
GND (Figure 1). The benefit of this GND bias is that the
amplifier outputs do not have a DC component, typically
V
conventional headphone amplifiers are unnecessary,
thus conserving board space, reducing system cost,
and improving frequency response. The device features
an undervoltage lockout that prevents operation from an
insufficient power supply and click-and-pop suppression
that eliminates audible transients on startup and shut-
down. Additionally, the MAX9722A/MAX9722B feature
thermal-overload and short-circuit protection and can
withstand ±8kV ESD strikes at the output pins.
The MAX9722 can be configured as a differential input
amplifier (Figure 2), making it compatible with many
CODECs. A differential input offers improved noise
immunity over a single-ended input. In devices such as
cellular phones, high-frequency signals from the RF
transmitter can couple into the amplifier’s input traces.
The signals appear at the amplifier’s inputs as com-
mon-mode noise. A differential input amplifier amplifies
the difference of the two inputs, and signals common to
both inputs are cancelled. Configured differentially, the
gain of the MAX9722 is set by:
R
R
The common-mode rejection ratio (CMRR) is limited by
the external resistor matching. For example, the worst-
case variation of 1% tolerant resistors results in 40dB
CMRR, while 0.1% resistors result in 60dB CMRR. For
best matching, use resistor arrays.
The R
R
results, use the MAX9722A.
8
DD
IN1
F2
IN2
_______________________________________________________________________________________
.
/2. The large DC-blocking capacitors required with
must be equal to R
= 15kΩ and R
IN1
and R
SS
). The headphone amplifiers operate from
F1
of the MAX9722B are internal, set
A
V
F2
Detailed Description
= R
IN2
= 30kΩ. However, for best
F1
, and R
/R
DD
IN1
Differential Input
), creating a negative
F1
must be equal to
Figure 1. Conventional Driver Output Waveform vs. MAX9722A/
MAX9722B Output Waveform
Figure 2. Differential Input Configuration
V
V
OUT
OUT
*R
IN+
IN-
R
IN1
IN1
CONVENTIONAL DRIVER-BIASING SCHEME
AND R
= R
IN2
R
R
, R
F1
DirectDrive BIASING SCHEME
IN1
IN2
F1
ARE INTERNAL FOR MAX9722B.
*
= R
F2
R
F2
R
F1
*
V
V
GND
+V
GND
-V
DD
DD
DD
DD
/2
OR -3V
OR 3V
OUT