MAX4410EUD Maxim Integrated Products, MAX4410EUD Datasheet - Page 12

• Manufacturer Part Number: MAX4410EUD
• Description: Audio Amplifiers
• Manufacturer: Maxim Integrated Products

Specifications of MAX4410EUD

• Product: Audio Line Drivers / Receivers
• Output Power: 80 mW
• Thd Plus Noise: 0.00%
• Supply Current: 7 mA
• Maximum Power Dissipation: 727 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-14
• Audio Load Resistance: 16 Ohms
• Input Offset Voltage: 0.5 mV
• Minimum Operating Temperature: - 40 C
• Lead Free Status / Rohs Status: No

80mW, DirectDrive Stereo Headphone Driver
with Shutdown
The MAX4410 stereo headphone driver features Maxim’s
DirectDrive architecture, eliminating the large output-
coupling capacitors required by traditional single-supply
headphone drivers. The device consists of two 80mW
Class AB headphone drivers, undervoltage lockout
(UVLO)/shutdown control, charge-pump, and compre-
hensive click-and-pop suppression circuitry (see Typical
Application Circuit). The charge pump inverts the posi-
tive supply (PV
The headphone drivers operate from these bipolar sup-
plies with their outputs biased about GND (Figure 1). The
drivers have almost twice the supply range compared to
other 3V single-supply drivers, increasing the available
output power. The benefit of this GND bias is that the dri-
ver outputs do not have a DC component typically
V
unnecessary, improving frequency response while con-
serving board space and system cost.
Each channel has independent left/right, active-low
shutdown controls, making it possible to optimize
power savings in mixed-mode, mono/stereo operation.
The device features an undervoltage lockout that pre-
vents operation from an insufficient power supply and
click-and-pop suppression that eliminates audible tran-
sients on startup and shutdown. Additionally, the
MAX4410 features thermal overload and short-circuit
protection and can withstand ±8kV ESD strikes on the
output pins.
Traditional single-supply headphone drivers have their
outputs biased about a nominal DC voltage (typically
half the supply) for maximum dynamic range. Large
coupling capacitors are needed to block this DC bias
from the headphone. Without these capacitors, a signif-
icant amount of DC current flows to the headphone,
resulting in unnecessary power dissipation and possi-
ble damage to both headphone and headphone driver.
Maxim’s DirectDrive architecture uses a charge pump
to create an internal negative supply voltage. This
allows the outputs of the MAX4410 to be biased about
GND, almost doubling dynamic range while operating
from a single supply. With no DC component, there is
no need for the large DC-blocking capacitors. Instead
of two large (220µF, typ) tantalum capacitors, the
MAX4410 charge pump requires two small ceramic
capacitors, conserving board space, reducing cost,
and improving the frequency response of the head-
phone driver. See the Output Power vs. Charge-Pump
Capacitance and Load Resistance graph in the Typical
Operating Characteristics for details of the possible
12
DD
/2. Thus, the large DC-blocking capacitors are
______________________________________________________________________________________
DD
), creating a negative supply (PV
Detailed Description
DirectDrive
SS
).
capacitor sizes. There is a low DC voltage on the driver
outputs due to amplifier offset. However, the offset of
the MAX4410 is typically 0.5mV, which, when com-
bined with a 32Ω load, results in less than 16µA of DC
current flow to the headphones.
Previous attempts to eliminate the output-coupling capac-
itors involved biasing the headphone return (sleeve) to
the DC-bias voltage of the headphone amplifiers. This
method raises some issues:
1) When combining a microphone and headphone on
2) The sleeve is typically grounded to the chassis.
3) During an ESD strike, the driver’s ESD structures
Figure 1. Traditional Driver Output Waveform vs. MAX4410
Output Waveform
a single connector, the microphone bias scheme
typically requires a 0V reference.
Using this biasing approach, the sleeve must be
isolated from system ground, complicating product
design.
are the only path to system ground. Thus, the driver
must be able to withstand the full ESD strike.
V
V
OUT
OUT
CONVENTIONAL DRIVER-BIASING SCHEME
DirectDrive BIASING SCHEME
GND
V
V
GND
+V
-V
DD
DD
DD
DD
/2