MAX9752BETI+ Maxim Integrated Products, MAX9752BETI+ Datasheet - Page 13

• Manufacturer Part Number: MAX9752BETI+
• Description: IC AMP AUDIO PWR 2.2W D 28TQFN
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive™r
• Type: Class Dr

Specifications of MAX9752BETI+

• Output Type: 2-Channel (Stereo) with Stereo Headphones
• Max Output Power X Channels @ Load: 2.2W x 2 @ 4 Ohm; 62mW x 2 @ 16 Ohm
• Voltage - Supply: 4.5 V ~ 5.5 V
• Features: Depop, Short-Circuit and Thermal Protection, Shutdown, Volume Control
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 3. MAX9752/MAX9753/MAX9754 Radiated Emissions with 76mm of Speaker Cable
Figure 4. Second-Generation Class D Output Waveform with
No Signal
The MAX9752/MAX9753/MAX9754 use Maxim’s unique
modulation scheme that eliminates the LC filter required
by traditional Class D amplifiers, improving efficiency,
reducing component count, and conserving board
space and system cost (Figure 4). With no input signal,
the outputs are two low-duty-cycle pulses that are in-
phase. This lowers the high-frequency energy and spec-
tral content. In comparison, conventional Class D
amplifiers output a 50% duty cycle when no input signal
is present. For most applications with short speaker
cables, no filtering is required.
V
OUT_
2.2W, Low-EMI, Stereo, Class D Power Amplifiers
+ - V
V IN_ = 0V
OUT_
OUT_+
OUT_-
- = 0V
Filterless Modulation/Common-Mode Idle
50
45
40
35
30
25
20
15
10
5
0
30
______________________________________________________________________________________
60
with DirectDrive Headphone Amplifiers
80
100
120
140
FREQUENCY (MHz)
160
Efficiency of a Class D amplifier is attributed to the
region of operation of the output stage transistors. In a
Class D amplifier, the output transistors act as switches
and consume negligible power. Any power loss associ-
ated with the Class D output stage is mostly due to the
I
current overhead.
The theoretical best efficiency of a linear amplifier is 78%,
however, that efficiency is only exhibited at peak output
powers. Under normal operating levels (typical music
reproduction levels), efficiency falls below 30%, whereas
the MAX9752/MAX9753/MAX9754 still exhibit > 80%
efficiencies under the same conditions (Figure 5).
Figure 5. MAX9752/MAX9753/MAX9754 Class D Efficiency vs.
MAX9750/MAX9751/MAX9755 Class AB Efficiency
2
R loss of the MOSFET on-resistance, and quiescent
180
200
100
90
80
70
60
50
40
30
20
10
0
0
MAX9752
MAX9753
MAX9754
220
EFFICIENCY vs. OUTPUT POWER
0.5
240
CLASS AB
OUTPUT POWER (W)
1.0
260
280
1.5
R
L
= 8Ω
300
2.0
Efficiency
13