wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 92

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

WM8400
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SPEAKER MIXER
ANALOGUE OUTPUTS
Figure 34 Speaker Boost Operation
DCGAIN[2:0] or ACGAIN[2:0]
000 = 1.00x
001 = 1.27x
010 = 1.40x
011 = 1.52x
100 = 1.67x
101 = 1.80x
AVDD
AGND
The speaker, headphone and line outputs are highly configurable and may be used in many different
ways.
SPEAKER OUTPUT CONFIGURATIONS
The speaker outputs SPKP and SPKN are driven by the speaker mixer SPKMIX, which can output a
mix that is any combination of the following signals:
The speaker mixer is controlled as described under “Output Signal Path”. The speaker mixer output
can be attenuated to avoid clipping when mixing multiple signal inputs.
The speaker outputs SPKP and SPKN operate in a BTL configuration in Class AB and Class D
amplifier modes. The mode is selected by register bit CDMODE. The outputs are capable of driving
1W into an 8Ω BTL load (or 500mW in class AB mode for thermal reasons) at room temperature. For
performance at higher temperatures, see Figure 1 in the “Recommended Operating Conditions”
section. Ultra-low leakage and high PSRR allow the speaker supply SPKVDD to be directly
connected to a lithium battery.
Six levels of AC and DC signal boost are provided in order to deliver maximum output power for
many commonly-used SPKVDD/AVDD combinations. These boost options are available in both
Class AB and Class D modes. The AC and DC gain levels from 1.0x to 1.8x are selected using
register bits ACGAIN and DCGAIN. To prevent pop noise, DCGAIN and ACGAIN should not be
modified while the speaker outputs are enabled.
Note that an appropriate SPKVDD supply voltage must be provided to prevent waveform clipping
when speaker boost is used.
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Left DAC and Right DAC outputs
LOMIX and ROMIX outputs via volume controls LOPGA and ROPGA
Line inputs LIN2 and RIN2
Output from left and right input mixers (AINLMUX and AINRMUX)
SPKATTN[1:0]
AGND
VMID
AVDD
DCGAIN[2:0]
SPKGND
SPKVDD
VMID x DCGAIN
ACGAIN[2:0]
PP, April 2009, Rev 3.0
BTL Connection
provides an
additional 6dB gain
SPKP
SPKN
Pre-Production
Signal x ACGAIN
VMID x DCGAIN
SPKGND
SPKVDD
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