CS43131 datasheet(32/156 Pages) CIRRUS

32 / 156 page

DS1155F1

CS43131

4.3 Class H Amplifier Output

The CS43131 has an independent set of controls for the DSD processor path as shown in Fig. 4-1. The DSD processor

also offers the control bit SIGCTL_DSDEQPCM, which maps the PCM_x setting to DSD_x setting, once enabled. As a

result, some of the DSD_x register settings are ignored. The registers affected are DSD_RAMP_UP, DSD_VOL_BEQA,

DSD_SZC, DSD_AMUTE, DSD_AMUTE_BEQA, DSD_MUTE_A, DSD_MUTE_B, DSD_INV_A, DSD_INV_B, DSD_

SWAP_CHAN, and DSD_COPY_CHAN. Refer to Section 7.4.1–Section 7.4.7 for control register details.

4.2.2

Wideband Flatness Mode

The CS43131 specifically optimizes for wideband flatness playback, which is enabled by PCM_WBF_EN bit. This mode

should only be enabled when PCM plays back at 192 kHz. When operating in other speeds or modes, this bit should be

properly disabled. If wideband flatness mode enabled, the filter spec complies to Table 3-10. There is no option for filter

roll-off or phase response in this mode. NOS filter mode should be disabled for proper operation. Note that wideband

flatness mode can only be enabled or disabled when PDN_HP is set.

4.2.3

Mono Mode

The CS43131 supports mono (differential) mode playback. Mono mode allows driving a differential interconnect such as

a XLR connector or implementing a stereo differential headphone utilizing two CS43131 devices. Fig. 2-2 shows a typical

connection of the CS43131 to a XLR connector in mono mode.

4.3 Class H Amplifier Output

Fig. 4-2 shows the Class H operation.

Figure 4-2. Class H Operation

The CS43131 headphone output amplifiers use Cirrus Logic two-mode Class H technology. This technology maximizes

operating efficiency of the typical Class AB amplifier while maintaining high performance. In a Class H amplifier design,

the rail voltages supplied to the amplifier vary with the needs of the music passage that is being amplified. This prevents

unnecessarily wasting energy during low power passages of program material or when the program material is played

back at a low volume level.

The internal charge pump, which creates the rail voltages for the headphone amplifiers, is the central component of the

two-mode Class H technology implemented in the CS43131. The charge pump receives its input voltage from the voltage

present on the VCP or VP pin. From this input voltage, the charge pump creates the differential rail voltages supplied to

the amplifier output stages. The charge pump can supply two sets of differential rail voltages: ±VCP and ±VP_LDO.

VCP

Class H Control

VCP_FILT–

–VCP

–VP_LDO V

VCP_FILT+

+VCP

+VP_LDO V

ADPT_PWR p. 131

CS43131 Datasheet(PDF) 32 Page - Cirrus Logic