MAX9776ETJ+ Maxim Integrated Products, MAX9776ETJ+ Datasheet - Page 23

• Manufacturer Part Number: MAX9776ETJ+
• Description: IC AMP AUDIO PWR 1.5W D 32TQFN
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive™r
• Type: Class Dr

Specifications of MAX9776ETJ+

• Output Type: 1-Channel (Mono) with Stereo Headphones
• Max Output Power X Channels @ Load: 1.5W x 1 @ 4 Ohm; 60mW x 2 @ 16 Ohm
• Voltage - Supply: 2.7 V ~ 5.5 V
• Features: Depop, Differential Inputs, I²C, Mute, Short-Circuit and Thermal Protection, Shutdown, Volume Control
• Mounting Type: Surface Mount
• Package / Case: 32-TQFN Exposed Pad
• Product: Class-D
• Output Power: 1.5 W
• Common Mode Rejection Ratio (min): 45 dB
• Thd Plus Noise: 0.04 %
• Operating Supply Voltage: 2.7 V to 5.5 V
• Supply Current: 9.5 mA
• Maximum Power Dissipation: 1360 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Amplifier Class: D
• No. Of Channels: 3
• Supply Voltage Range: 2.7V To 5.5V
• Load Impedance: 4ohm
• Operating Temperature Range: -40°C To +85°C
• Amplifier Case Style: TQFN
• Rohs Compliant: Yes
• For Use With: MAX9776EVKIT+ - EVALUATION KIT FOR MAX9776
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 5. Traditional Amplifier Output vs. MAX9775/MAX9776
DirectDrive Output
The MAX9775/MAX9776 feature a low-noise charge
pump. The switching frequency of the charge pump is
half the switching frequency of the Class D amplifier,
regardless of the operating mode. The nominal switch-
ing frequency is well beyond the audio range, and thus
does not interfere with the audio signals, resulting in an
SNR of 93dB. Although not typically required, addition-
al high-frequency noise attenuation can be achieved by
increasing the size of C2 (see the Typical Application
Circuits ). The charge pump is active in both speaker
and headphone modes.
The MAX9775 features a 3D stereo enhancement func-
tion, allowing the MAX9775 to widen the stereo sound field
and immerse the listener in a cleaner, richer sound experi-
ence. Note the MAX9776, mono Class D speaker amplifier
does not feature 3D stereo enhancement.
As stereo speaker applications become more compact,
the quality of stereophonic sound is jeopardized.
V
V
OUT
OUT
2 x 1.5W, Stereo Class D Audio Subsystem
CONVENTIONAL DRIVER-BIASING SCHEME
______________________________________________________________________________________
DirectDrive BIASING SCHEME
with DirectDrive Headphone Amplifier
3D Enhancement
GND
V
V
GND
+V
-V
Charge Pump
DD
DD
DD
DD
/ 2
With Maxim’s 3D stereo enhancement, it is possible to
emulate stereo sound in situations where the speakers
must be positioned close together. As shown in Figure
6, wave interference can be used to cancel the left
channel in the vicinity of the listener’s right ear and vice
versa. This technique can yield an apparent separation
between the speakers that is a factor of four or greater
than the actual physical separation.
The external capacitors CL_L, CL_H, CR_L, and CR_H
set the starting and stopping range of the 3D effect.
CL_H and CR_H are for the lower limit (in the MAX9775
Typical Application Circuit , it is 1kHz), CR_L and CL_L
are for the higher limit (10kHz). The internal resistor is
typically 7kΩ and the frequencies are calculated as:
where R = 7kΩ and C = CR_H and CL_H.
where R = 7kΩ and C = CR_L and CL_L.
For example, with CR_L = CL_L = 2.2nF and CR_H =
CL_H = 22nF, the 3D start frequency is 1kHz and the
3D stop frequency is 10kHz.
Enabling the 3D sound effect results in an apparent 6dB
gain because the internal left and right signals are mixed
together. This gain can be nulled by volume adjusting
the left and right signals. The volume control can be pro-
grammed through the I
pensate for the extra 6dB increase in gain. For example,
Figure 6. MAX9775 3D Stereo Enhancement
RIGHT
LEFT
3
3
I
I
L
R
D START
D STOP
Q
Q
_
_
R
L
+
+
2
C-compatible interface to com-
=
=
d
2
2
π
1
π
RC
1
RC
LISTENER
RIGHT
LEFT
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