max97200 Maxim Integrated Products, Inc., max97200 Datasheet - Page 8

• Manufacturer Part Number: max97200
• Description: Low-power, Low-offset, Dual Mode, Class H Directdrive Headphone Amplifier
• Manufacturer: Maxim Integrated Products, Inc.

Low-Power, Low-Offset, Dual Mode, Class H
DirectDrive Headphone Amplifier
The MAX97200 is a 45mW Class H headphone ampli-
fier that runs from a single low 1.8V supply voltage
and employs Maxim’s second-generation DirectDrive
technology.
Maxim’s patented DirectDrive architecture uses an
inverting charge pump to derive a negative voltage sup-
ply. The headphone amplifier is powered between the
positive supply and the generated negative rail. This
scheme allows the audio output signal to be biased
about ground, eliminating the need for large DC block-
ing capacitors between the amplifier output and the
headphone load.
Second-generation DirectDrive technology improves
power consumption when compared to first-generation
DirectDrive amplifiers. The MAX97200 can be powered
from a regulated 1.8V supply and have similar power
consumption to a traditional DirectDrive amplifier that is
powered from 0.9V.
The MAX97200 features a dual-mode internal charge
pump to generate the power rails for the DirectDrive
amplifier. The charge-pump output can be QPVIN/2 or
QPVIN depending on the amplitude of the output signal.
When the output voltage is low the power-supply volt-
age is QPVIN/2. When the output signal demands larger
output voltage, the charge pump switches modes so
that a greater power-supply voltage is realized and more
output power can be delivered to the load.
Traditional single-supply headphone amplifiers have
outputs biased at a nominal DC voltage (typically half
the supply). Large coupling capacitors are needed to
block this DC bias from the headphone. Without these
capacitors, a significant amount of DC current flows to
the headphone, resulting in unnecessary power dis-
sipation and possible damage to both headphone and
headphone amplifier.
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DirectDrive Headphone Amplifier
Detailed Description
Maxim’s second-generation DirectDrive architecture
uses a charge pump to create an internal negative sup-
ply voltage. This allows the headphone outputs of the
MAX97200 to be biased at GND while operating from a
single supply (Figure 1). Without a DC component, there
is no need for the large DC-blocking capacitors. Instead
of two large (220FF typ) capacitors, the MAX97200
charge pump requires 3 small ceramic capacitors, con-
serving board space, reducing cost, and improving the
frequency response of the headphone amplifier.
Figure 1. Traditional Amplifier vs. MAX97200 DirectDrive
Output
V
DD
+V
-V
GND
GND
V
DD
DD
DD
/ 2
V
V
OUT
OUT
CONVENTIONAL DRIVER BIASING SCHEME
DirectDrive BIASING SCHEME
2V
V
DD
DD