WM8978 Wolfson Microelectronics Ltd., WM8978 Datasheet - Page 45

no-image

WM8978

Manufacturer Part Number
WM8978
Description
The WM8978 is a low power, high quality stereo codec designed for portable applications such as Digital still camera or Digital Camcorde
Manufacturer
Wolfson Microelectronics Ltd.
Datasheet

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
WM8978CGEFL/RV
Manufacturer:
WOLFSON
Quantity:
10 000
Part Number:
WM8978G
Manufacturer:
SANYO
Quantity:
87 018
Company:
Part Number:
WM8978G
Manufacturer:
WM
Quantity:
115
Company:
Part Number:
WM8978GEFL,,7500,QFN32,WOLFSON,,,,16+
0
Part Number:
WM8978GEFL/RV
Manufacturer:
WOLFSON
Quantity:
9 870
Part Number:
WM8978GEFL/RV
Manufacturer:
WM
Quantity:
1 000
Preliminary Technical Data
w
Figure 22 DAC Digital Limiter Operation
VOLUME BOOST
The limiter has a programmable upper threshold which is close to 0dB. Referring to Figure 22, in
normal operation (LIMBOOST=000 => limit only) signals below this threshold are unaffected by the
limiter.
LIMATK register bits) until the signal falls below the threshold. The limiter also has a lower threshold
1dB below the upper threshold. When the signal falls below the lower threshold the signal is
amplified at a specific decay rate (controlled by LIMDCY register bits) until a gain of 0dB is reached.
Both threshold levels are controlled by the LIMLVL register bits. The upper threshold is 0.5dB above
the value programmed by LIMLVL and the lower threshold is 0.5dB below the LIMLVL value.
The limiter has programmable upper gain which boosts signals below the threshold to compress the
dynamic range of the signal and increase its perceived loudness. This operates as an ALC function
with limited boost capability. The volume boost is from 0dB to +12dB in 1dB steps, controlled by the
LIMBOOST register bits.
The output limiter volume boost can also be used as a stand alone digital gain boost when the limiter
is disabled.
Signals above the upper threshold are attenuated at a specific attack rate (set by the
PTD Rev 2.6 November 2005
WM8978
45