MAX4295EEE+ Maxim Integrated Products, MAX4295EEE+ Datasheet - Page 8

• Manufacturer Part Number: MAX4295EEE+
• Description: IC AMP AUDIO PWR 2W MONO 16QSOP
• Manufacturer: Maxim Integrated Products
• Type: Class Dr

Specifications of MAX4295EEE+

• Output Type: 1-Channel (Mono)
• Max Output Power X Channels @ Load: 2W x 1 @ 4 Ohm
• Voltage - Supply: 2.7 V ~ 5.5 V
• Features: Depop, Short-Circuit and Thermal Protection, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX4295 switch-mode, Class D audio power
amplifier is intended for portable multimedia and gener-
al-purpose audio applications. Linear amplifiers in the
1W to 2W output range are inefficient; they overheat
when operated near rated output power levels. The effi-
ciency of linear amplifiers is <50% when the output
voltage is equal to 1/2 the supply. The MAX4295 Class
D amplifier achieves efficiencies of 87% or greater and
is capable of delivering up to 2W of continuous maxi-
mum power to a 4Ω load. The lost power is due mainly
to the on-resistance of the power switches and ripple
current in the output.
In a Class D amplifier, a PWM controller converts the
analog input to a variable pulse-width signal. The pulse
width is proportional to the input voltage, ideally 0% for
a 0V input signal and 100% for full-scale input voltages.
A passive lowpass LC network filters the PWM output
waveform to reconstruct the analog signal. The switch-
ing frequency is selected much higher than the maxi-
Mono, 2W, Switch-Mode (Class D)
Audio Power Amplifier
8
Figure 1. Functional Diagram
_______________________________________________________________________________________
IN
AOUT
CSS
0.3
FS2
FS1
(VCM)
✕
V
SS
CC
Detailed Description
POWER MANAGEMENT
AND PROTECTION
PWM
OSC
GND
V
CC
MAX4295
mum input frequencies so that intermodulation products
are outside the input signal bandwidth. Higher switching
frequencies also simplify the filtering requirements.
The MAX4295 consists of an inverting input operational
amplifier, a PWM ramp oscillator, a controller that con-
verts the analog input to a variable pulse-width signal,
and a MOSFET H-bridge power stage (Figure 1). The
control signal is generated by the PWM comparator; its
pulse width is proportional to the input voltage. Ideally
the pulse width varies linearly between 0% for a 0V
input signal and 100% for full-scale input voltages
(Figure 2). This signal controls the H-bridge. The
switches work in pairs to reverse the polarity of the sig-
nal in the load. Break-before-make switching of the H-
bridge MOSFETs by the driver circuit keeps supply
current glitches and crowbar current in the MOSFETs at
a low level. The output swing of the H-bridge is a direct
function of the supply voltage. Varying the oscillator
swing in proportion to the supply voltage maintains
constant gain with varying supply voltage.
DRIVE
DRIVE
GATE
GATE
PGND
PGND
PV
PV
CC
CC
OUT-
OUT+