Cirrus Logic CS42L42 Manual page 42

Table 4-3 shows the nominal signal- and volume-level ranges if the amplifier is set to the adapt-to-signal mode explained
in Section 4.6.1. In addition to adapting to the input signal, the Class H control is capable of monitoring the internal
headphone amplifier supply to allow more efficient, load-dependent, automatic Smart Class H Mode selection. In fixed
modes, if the signal level exceeds the maximum value of the indicated range, clipping can occur.
Load
Resistance Capacitance
15 
30 
1 or 10 nF
3 k 1 or 10 nF
1.In Adapt-to-Signal Mode, volume level ranges are approximations but are within –0.5 dB from the values shown.
2.Relative to digital full scale with FULL_SCALE_VOL set to 0 dB.
3.In fixed modes, clipping occurs if the signal level exceeds the maximum of this range due to setting the amplifier's supply too low.
4.To optimize efficiency, smart Class H thresholds automatically vary based on load conditions.
4.6.1 Power Control Options
This section describes the supported types of operation: standard Class AB and adapt to signal. The set of rail voltages
supplied to the amplifier output stages depends on the ADPTPWR setting, as described in
4.6.1.1 Standard Class AB Operation (ADPTPWR = 001, 010, 011, or 100)
If ADPTPWR is set to 001, 010, 011, or 100, the rail voltages supplied to the amplifiers are held to ±2.5, ±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. In these settings, the CS42L42 amplifiers operate in a traditional Class AB configuration.
4.6.1.2 Adapt-to-Output Signal (ADPTPWR = 111)
If ADPTPWR = 111, the rail voltage sent to the amplifiers is based only on whether the signal sent to the amplifiers would
cause the amplifiers to clip when operating on the lower set of rail voltages at certain threshold values.
• If clipping can occur, the control logic instructs the charge pump to provide the next higher set of rail voltages.
• If clipping could not occur, the control logic instructs the charge pump to provide the lower set of rail voltages,
eliminating the need to advise the CS42L42 of volume settings external to the device.
DS1083F2
Table 4-3. Class H Supply Modes
Mode
1 nF 0
1
2
3
10 nF 0
1
2
3
0
1
2
3
0
1
2
3
Class-H Supply Voltage
±2.5 V
± VCP
± VCP/2
± VCP/3
±2.5 V
± VCP
± VCP/2
± VCP/3
±2.5 V
± VCP
± VCP/2
± VCP/3
±2.5 V
± VCP
± VCP/2
± VCP/3
CS42L42
4.6 Class H Amplifier
1 , 2 , 3 , 4
Signal-Level Range
≥ –8 dB
–9 to –14 dB
–15 to –20 dB
≤ –21 dB
≥ –9 dB
–10 to –14 dB
–15 to –19 dB
≤ –20 dB
≥ –4 dB
–5 to –11 dB
–12 to –16 dB
≤ –17 dB
≥ –1 dB
–2 to –8 dB
–9 to –13 dB
≤ –14 dB
Section 7.14.1.
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