WM8974GEFL/V Wolfson Microelectronics, WM8974GEFL/V Datasheet - Page 36

• Manufacturer Part Number: WM8974GEFL/V
• Description: Audio CODECs Mono Codec with Spkr
• Manufacturer: Wolfson Microelectronics

Specifications of WM8974GEFL/V

• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-24
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8974
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DIGITAL HI-FI DAC VOLUME CONTROL
Table 23 DAC Volume
HI-FI DIGITAL TO ANALOGUE CONVERTER (DAC)
Table 24 De-Emphasis
Table 25 DAC Enable
Table 26 DAC Control Register
The analogue output from the DAC can then be mixed with the AUX analogue input and the ADC
analogue input. The mix is fed to the output drivers, SPKOUTP/N, and MONOOUT.
MONOOUT: can drive a 16Ω or 32Ω headphone or line output or can be a buffered version of VMID
(When MONOMUTE=1).
SPKOUTP/N: can drive a 16Ω or 32Ω stereo headphone or stereo line output, or an 8Ω BTL mono
speaker.
The signal volume from each Hi-Fi DAC can be controlled digitally. The gain and attenuation range
is –127dB to 0dB in 0.5dB steps. The level of attenuation for an eight-bit code X is given by:
0.5 × (X-255) dB for 1 ≤ X ≤ 255;
After passing through the graph uxiliaryser filters, digital ‘de-emphasis’ can be applied to the audio
data if necessary (e.g. when the data comes from a CD with pre-emphasis used in the recording).
De-emphasis filtering is available for sample rates of 48kHz, 44.1kHz and 32kHz.
The DAC is enabled by the DACEN register bit.
The WM8974 also has a Soft Mute function, which gradually attenuates the volume of the digital
signal to zero. When removed, the gain will ramp back up to the digital gain setting. This function is
enabled by default. To play back an audio signal, it must first be disabled by setting the DACMU bit
to zero.
R10
DAC Control
R11
DAC Digital
Volume
R10
DAC Control
R3
Power Management
3
REGISTER
ADDRESS
REGISTER
ADDRESS
REGISTER
REGISTER
ADDRESS
ADDRESS
7:0
BIT
BIT
5:4
0
6
BIT
BIT
DACVOL
[7:0]
DACMU
DEEMPH
DACEN
LABEL
LABEL
LABEL
LABEL
MUTE for X = 0
00
0
DEFAULT
DEFAULT
0
11111111
( 0dB )
DEFAULT
DEFAULT
De-Emphasis Control
00 = No de-emphasis
01 = 32kHz sample rate
10 = 44.1kHz sample rate
11 = 48kHz sample rate
DAC enable
0 = DAC disabled
1 = DAC enabled
DAC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -127dB
0000 0010 = -126.5dB
... 0.5dB steps up to
1111 1111 = 0dB
DAC soft mute enable
0 = DACMU disabled
1 = DACMU enabled
PD, Rev 4.5, September 2008
DESCRIPTION
DESCRIPTION
DESCRIPTION
DESCRIPTION
Production Data
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