Class h operation – Rainbow Electronics MAX98088 User Manual
Page 104
Stereo Audio Codec
with FLEXSOUND Technology
MAX98088
104
Class H Operation
A Class H amplifier uses a Class AB output stage with
power supplies that are modulated by the output signal.
In the case of the ICs, two nominal power-supply differ-
entials of 1.8V (+0.9V to -0.9V) and 3.6V (+1.8V to -1.8V)
are available from the charge pump. Figure 29 shows the
operation of the output-voltage-dependent power supply
Figure 28. Traditional Amplifier Output vs. DirectDrive Output
Figure 30. Headphone Amplifier Block Diagram
Figure 29. Class H Operation
V
DD
V
DD
/2
GND
CONVENTIONAL AMPLIFIER BIASING SCHEME
DirectDrive AMPLIFIER BIASING SCHEME
+V
DD
GND
-V
DD
(V
SS
)
DALEN
DACL
DAREN
DACR
MIXHPR
MIX
MIXHPL
MIX
MIXHPL_
PATH SEL
MIXHPR_
PATH SEL
HPVOLL:
+3dB TO -67dB
HPL
HPSNS
HPLEN
HPVOLR:
+3dB TO -67dB
HPR
HPREN
TBD
TBD
1.8V
0.9V
V
TH_H
V
TH_L
-0.9V
-1.8V
HPVDD
HPVSS
OUTPUT
VOLTAGE