MAX98400AETX+ Maxim Integrated Products, MAX98400AETX+ Datasheet - Page 16

• Manufacturer Part Number: MAX98400AETX+
• Description: Audio Amplifiers Stereo, High Power, r, Class D Amplifier
• Manufacturer: Maxim Integrated Products

Specifications of MAX98400AETX+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX98400A/MAX98400B are available in 36-pin
and 24-pin TQFN packages, respectively, and are
specified over the -40NC to +85NC temperature range.
The high efficiency of a Class D amplifier is due to the
switching operation of the output stage transistors. In a
Class D amplifier, the output transistors act as switches
and consume negligible power. Power loss associated
with the Class D output stage is due to the I
MOSFET on-resistance, various switching losses, and
quiescent current overhead.
The theoretical best efficiency of a linear amplifier is 78%
at peak output power. Under typical music reproduction
levels, the efficiency falls below 30%, whereas these
ICs exhibit > 85% efficiency under the same conditions
(Figure 2).
The ICs feature a shutdown mode that reduces power
consumption and extends battery life in portable appli-
cations. The shutdown mode reduces supply current to
8FA (typ). Drive SHDN high for normal operation. Drive
SHDN low to place the device in low-power shutdown
mode. In shutdown mode, the outputs are high imped-
ance and the common-mode voltage at the output
decays to zero. The shutdown mode serves as a mute
function.
Stereo, High-Power, Class D Amplifiers
16
Figure 1. MAX98400B EMI Performance
-10
40
30
20
10
0
30
FREQUENCY (MHz)
100
2
Efficiency
Shutdown
1000
R loss of the
The ICs feature comprehensive click-and-pop suppres-
sion that minimizes audible transients on startup and
shutdown. While in shutdown, the H-bridge is in a high-
impedance state.
The MAX98400A features a mono mode that allows the
right and left channels to operate in parallel, achieving
up to 40W of output power. Apply a logic-high (V
MONO to enable mono mode. In mono mode, an audio
signal applied to the left channel (INL) is routed to the
H-bridges of both channels. Connect OUTL+ to OUTR+
and OUTL- to OUTR- using heavy PCB traces as close
as possible to the device. Driving MONO low (stereo
mode) while the outputs are wired together in mono
mode can trigger the short-circuit or thermal-overload
protection, or both.
The ICs feature a programmable clipping limiter to pre-
vent output clipping distortion and excessive power dis-
sipation and to protect small speakers. All limiter func-
tionality is controlled by two pins: LIM_TH and RELEASE.
The voltage applied at the LIM_TH pin controls the
threshold when the limiter acts, and the capacitor at the
RELEASE pin controls the release time of the limiter. The
limiter controls both left and right channels together.
Figure 2. MAX98400A Efficiency vs. Class AB Efficiency
100
90
80
70
60
50
40
30
20
10
0
0
EFFICIENCY vs. OUTPUT POWER
Click-and-Pop Suppression
TOTAL OUTPUT POWER (W)
5
MAX98400A
10
Mono Configuration
CLASS AB
Clipping Limiter
15
20
S
) to