MAX98090AETL+ Maxim Integrated, MAX98090AETL+ Datasheet - Page 134

• Manufacturer Part Number: MAX98090AETL+
• Description: Interface - CODECs 5V 130mW Stereo Headphone Amp
• Manufacturer: Maxim Integrated

Specifications of MAX98090AETL+

• Rohs: yes

MAX98090
Efficient Class D Speaker Output Driver
A Class D amplifier offers much higher efficiency than
a Class AB amplifier. The high efficiency is due to the
switching operation of the output stage transistors. In a
Class D amplifier, the output transistors act as current
steering switches and consume negligible additional
power. Any power loss associated with a Class D output
stage is primarily due to the loss in the MOSFET on-
resistance, and the baseline quiescent current overhead.
For comparison, the theoretical best-case efficiency of a
linear amplifier is 78%. However, that efficiency is only
possible at peak output power conditions. Under normal
operating levels (typical music reproduction levels), effi-
ciency often falls below 30%. Under the same conditions,
the device’s differential Class D speaker output amplifier
still exhibits 80% efficiency.
By default, the Class D output switching clocks are inde-
pendently generated for the left and right channels. With
slave mode enabled, the right channel becomes a slave
to the left channel and uses the same clock (Table 65).
In slave mode, the switching scheme is synchronous. As
Figure 36. DirectDrive Headphone Output Functional Diagram
www.maximintegrated.com
DACLEN
DRIVERS
ANALOG
INPUT
LEFT
DAC
MAX98090
TECHNOLOGY
FLEXSOUND
PERFMODE
DACHP
DSP
RIGHT
DAC
DACREN
SPEAKER/RECEIVER/
LINE OUT
LINE A
LINE B
LINE A
LINE B
DACR
DACR
DACL
MIC 1
MIC 2
DACL
MIC 1
MIC 2
MIXER
MIXER
RIGHT
LEFT
HP
HP
a result, slave mode operation eliminates potential beat
tones that can occur with asynchronous stereo Class D
switching.
Traditional Class D amplifiers often require the use of
external LC filters and/or shielding to meet EN55022B
and FCC electromagnetic-interference (EMI) regulation
standards. Maxim’s patented active emissions limiting
edge-rate control circuitry reduces EMI emissions. This
allows the device to drive both 4Ω and 8Ω without any
additional output filtering. The filterless Class D outputs
are designed for typical applications where the trace
length to the speakers is short and has a low series
resistance. See the
section for application level details.
Analog Class-H Headphone Output
The stereo headphone output driver has a flexible input
mixer, programmable gain stage, an integrated charge
pump, and a ground referenced DirectDrive Class H
output amplifier (Figure 36). The headphone output
amplifier is capable of driving both 16Ω and 32Ω ground-
referenced headphone loads.
-12dB TO 0dB
-12dB TO 0dB
Ultra-Low Power Stereo Audio Codec
MIXHPLG[1:0]
MIXHPRG[1:0]
MIXHPL[5:0]
MIXHPR[5:0]
MIXHPRSEL
MIXHPLSEL
RIGHT
LEFT
MUX
MUX
HP
HP
Filterless Class D Speaker Operation
HEADPHONE
HEADPHONE
HPVOLL[4:0]
HPVOLR[4:0]
RIGHT PGA
LEFT PGA
HPLEN
HPREN
VS2EN
HPLM
ZDEN
ZSEN
HPRM
-67dB TO 3dB
-67dB TO 3dB
C1P C1N CPVDD CPVSS
CHARGE PUMP
DIRECT DRIVE
HEADPHONE
Maxim Integrated │ 134
HPL
HPSNS
HPR
HPVDD
HPGND