CS43131 datasheet(33/156 Pages) CIRRUS

33 / 156 page

DS1155F1

CS43131

4.3 Class H Amplifier Output

HV_EN setting, as shown in Fig. 4-3, determines the VP_LDO voltage as shown in Table 4-1. HV_EN = 1 setting is

required to support the 1.7-V full-scale voltage for a 600-

 load and above. In this setting, minimum VP is required to be

higher than 3.3 V, and any load below 600

 is not supported. When HV_EN = 0, the max output voltage is 1.4-V RMS

full-scale voltage. In this setting, minimum VP is required to be higher than 3 V, and the full headphone load range is

supported.

Figure 4-3. Internal LDO Configuration

Table 4-2 shows the nominal signal and volume level ranges when the output is set to the adapt modes explained in

Section 4.3.1. If the signal level is greater than the maximum value of this range, then clipping can occur.

4.3.1

Power Supply Control Options

This section describes the two types of operation: standard Class AB and adapt-to-output signal. The set of rail voltages

supplied to the amplifier output stages depends on the ADPT_PWR (see p. 131) setting.

4.3.1.1 Standard Class AB Operation (ADPT_PWR = 001 or 010)

If ADPT_PWR is set to 001 or 010, the rail voltages supplied to the amplifiers are held to ±VP_LDO or ±VCP, respectively.

The rail voltages supplied to the output stages are held constant, regardless of the output signal level. The CS43131

amplifiers simply operate in a traditional Class AB configuration.

4.3.1.2 Adapt-to-Output Signal (ADPT_PWR = 111)

If ADPT_PWR is set to 111, the rail voltage sent to the amplifiers is based solely 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 it would cause clipping, the control logic instructs the charge pump to provide the next higher set of rail voltages

to the amplifiers.

• If it would not cause clipping, the control logic instructs the charge pump to provide the lower set of rail voltages to

the amplifiers, eliminating the need to advise the CS43131 of volume settings external to the device.

Table 4-1. VP_LDO Voltage Per HV_EN Setting

HV_EN

VP_LDO Voltage

02.6 V

13.0 V

Table 4-2. Class H Supply Modes

Mode

Class H Supply Level

Signal 1 or Volume Level Range 2,3,4

1.In adapt-to-signal, the volume level ranges are approximations but are within –0.5 dB from the values shown.

2.Relative to digital full scale with output gain set to 0 dB.

3.In fixed modes, clipping can occur if the signal level exceeds the maximum of this range due to setting the

amplifier’s supply too low.

4.Thresholds shown are nominal for a 16-Ω stereo load.

±VP_LDO V, internally regulated from VP

 –11 dB

±VCP

< –11 dB

VP_LDO

Internal

LDO

HV_EN p. 131

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