Cirrus Logic CS42L73 - Manual (Page 45)

DS882F1 45
CS42L73
4.5.1.1 Standard Class AB Operation (Mode 001, 010, and 011)
When the ADPTPWR is set to 001, 010, or 011, the rail voltages supplied to the amplifiers will be held to
±VCP, ±VCP/2, or ±VCP/3, respectively. For these settings, the rail voltages supplied to the output stages
are held constant, regardless of the signal level, internal volume settings, or the settings of the advisory
volume registers. In these settings, the amplifiers in the CS42L73 simply operate in a traditional Class AB
configuration.
Note: In the 010 or 011 setting, clipping can occur if the input signal level exceeds the headroom of the
output amplifier.
4.5.1.2 Adapt-to-Volume Settings (Mode 000)
If the Adaptive Power bits are set to 000, the CS42L73 determines which set of rail voltages to send to
the amplifiers based upon the gain and attenuation levels of all active internal processing blocks. To adjust
for digital (DSP) input volume settings, it also takes into account the settings of the advisory volume reg-
isters. The combined effect of all volume settings is shown in
Figure 18 .
If the total gain and attenuation set in the volume control registers would cause the amplifiers to clip the
signal with the lowest voltage setting (±VCP/3), the control logic instructs the charge pump to provide the
next higher set of the rail voltages (±VCP/2, then ±VCP) to the amplifiers until the signal is no longer
clipped or the charge pump is in its highest mode (±VCP).
Note that the A and B channels of each respective volume control must both cross the threshold to trigger
a change to a lower VCP mode. If either channel crossed the threshold in an upward direction, the charge
pump will switch to a higher VCP mode. The control logic also monitors various functions (listed in the
following table) that may affect the total gain and attenuation of the signal applied to the amplifiers.
HL_PLYBCKB =A
HLxDMUTE
HLxDVOL
Charge Pump
Headphone
Amplifiers
Lineout
Amplifiers
ASPINV
VSPINV
XSPINV
PDN_HP
HPxAVOL
HPxAMUTE
PDN_LO
LOxAVOL
LOxAMUTE
PDN_ADCx
PDN _DMICx
IPB=A
PGAB =A
PGAxMUX
Headphone
Volume Settings :
Lineout
Volume Settings :
Analog Input
Volume Settings :
ASP/VSP/XSP
Advisory
Volume Settings :
DAC
Volume Settings :

DAC Limiter
ALC
DAC Mixer
HLx_IPx
HLx_XSPx
HLx_ASPx
HLx_VSPM
STRINV
Stereo Input
Advisory
Volume Settings :
BOOSTx
IPxMUTE
MIC_PREAMPx
PGAxVOL
IPxDVOL
Figure 18. Class H Control - Adapt-to-Volume Mode