A22H165 Datasheet, PDF (23/36 Pages) STMicroelectronics – High-performance class-G stereo headphone amplifier

A22H165
Application information
Figure 65. Efficiency comparison
100
Both channels enabled
RL = 32 Ω, F = 1 KHz
Vcc = 3.6 V, Ta = 25°C
Crest Factor = 3dB
10
Class G
1
Class AB
0. 1
0. 1
1
10
Total Output Power (mW)
Most audio signals have a crest factor higher than 6 dB (10 dB on average), which means
that most of the time the music level is low. In this case, the setting of the internal DC-DC
converters is low (1.2 V) and in this way, helps to minimize the power dissipation.
When the audio signal amplitude increases due to a peak or louder music, the setting of the
internal DC-DC converters increases to 1.9 V, automatically increasing the output dynamic
range. This 1.9 V value remains until the end of the decay time.
Figure 66 shows a music sample played at high levels.
Figure 66. Class-G operating with a music sample
HPVDD
High 1.9V
HPVDD
Low 1.2V
Music
Sample
Note:
PVSS
Low -1.2V
PVSS
High -1.9V
HPVDD/PVSS voltages are created internally by DC-DC converters. To avoid destruction of
the A22H165 power amplifier, do not connect any external power supply on these pins.
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