MAX4411ETP+ Maxim Integrated Products, MAX4411ETP+ Datasheet - Page 10

• Manufacturer Part Number: MAX4411ETP+
• Description: IC AMP AUDIO .08W STER AB 20TQFN
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive™r
• Type: Class ABr

Specifications of MAX4411ETP+

• Output Type: Headphones, 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 80mW x 2 @ 16 Ohm
• Voltage - Supply: 1.8 V ~ 3.6 V
• Features: Depop, Short-Circuit and Thermal Protection, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 20-TQFN Exposed Pad
• Product: General Purpose Audio Amplifiers
• Output Power: 80 mW
• Thd Plus Noise: 0.007 %
• Operating Supply Voltage: 1.8 V to 3.6 V
• Supply Current: 3.2 mA
• Maximum Power Dissipation: 1349 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 1.8 V
• Amplifier Class: AB
• No. Of Channels: 2
• Supply Voltage Range: 1.8V To 3.6V
• Load Impedance: 16ohm
• Operating Temperature Range: -40°C To +85°C
• Amplifier Case Style: TQFN
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
method raises some issues:
•
•
•
•
In addition to the cost and size disadvantages of the DC-
blocking capacitors required by conventional head-
phone amplifiers, these capacitors limit the amplifier’s
low-frequency response and can distort the audio signal:
1) The impedance of the headphone load and the DC-
10
Figure 2. Earbud Speaker/Microphone Combination Headset
Configuration
blocking capacitor forms a highpass filter with the
-3dB point set by:
MICROPHONE
The sleeve is typically grounded to the chassis.
Using this biasing approach, the sleeve must be
isolated from system ground, complicating product
design.
During an ESD strike, the driver’s ESD structures
are the only path to system ground. Thus, the driver
must be able to withstand the full ESD strike.
When using the headphone jack as a line out to other
equipment, the bias voltage on the sleeve may con-
flict with the ground potential from other equipment,
resulting in possible damage to the drivers.
When using a combination microphone and speaker
headset, the microphone typically requires a GND
reference. The driver DC bias on the sleeve conflicts
with the microphone requirements (Figure 2).
______________________________________________________________________________________
AMPLIFIER
OUTPUT
AUDIO
AUDIO
INPUT
INPUT
HEADPHONE DRIVER
MICROPHONE
AMPLIFIER
MAX4411
Low-Frequency Response
MICROPHONE
BIAS
2) The voltage coefficient of the DC-blocking capacitor
Figure 3. Low-Frequency Attenuation for Common DC-Blocking
Capacitor Values
where R
C
The highpass filter is required by conventional sin-
gle-ended, single power-supply headphone drivers
to block the midrail DC-bias component of the audio
signal from the headphones. The drawback to the
filter is that it can attenuate low-frequency signals.
Larger values of C
in physically larger, more expensive capacitors.
Figure 3 shows the relationship between the size of
C
Note that the -3dB point for a 16Ω headphone with a
100µF blocking capacitor is 100Hz, well within the nor-
mal audio band, resulting in low-frequency attenuation
of the reproduced signal.
contributes distortion to the reproduced audio signal
as the capacitance value varies as the function of
the voltage across the capacitor changes. At low
frequencies, the reactance of the capacitor domi-
nates at frequencies below the -3dB point and the
voltage coefficient appears as frequency-depen-
dent distortion. Figure 4 shows the THD+N intro-
OUT
OUT
is the value of the DC-blocking capacitor.
and the resulting low-frequency attenuation.
-12
-15
-18
-21
-24
-27
-30
-3
-6
-9
L
0
10
is the impedance of the headphone and
f
−
LOW-FREQUENCY ROLLOFF
3
dB
100
OUT
FREQUENCY (Hz)
=
33μF
(R
100μF
L
2π
220μF
reduce this effect but result
= 16Ω)
1k
330μF
R C
DirectDrive
L OUT
1
10k
100k