Fujitsu EVB JADE--D, Руководство пользователя

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Preliminary
34(45)
Prepared Document Number
Manfred Ortmann
Approved Checked Date Revision Storage
2009­10­05 PA 4.2 Mycable01
2.2.8 Audio CODEC
Pic. 2­10: Audio connectors
A 104 dB, 24­Bit, 192 kHz Stereo Audio CODEC CS4245 ( U701 ) from Cirrus Logic is
populated.
The CS4245 is a highly integrated stereo audio CODEC. The CS4245 performs stereo analog­
to­digital ( A / D ) and digital­to­analog ( D / A ) conversion of up to 24­bit serial values at
sample rates up to 192 kHz. A 6:1 stereo input multiplexer is included for selecting between
line­level or microphone­level inputs. The microphone input path includes a +32 dB gain stage
and a low­noise bias voltage supply. The PGA is available for line or microphone inputs and
provides gain / attenuation of ±12 dB in 0.5 dB steps. The output of the PGA is followed by an
advanced 5th order, multi­bit delta sigma modulator and digital filtering / decimation. Sampled
data is transmitted by the serial audio interface at rates from 4 kHz to 192 kHz in either Slave or
Master Mode. The D/A converter is based on a 4th­order multi­bit delta sigma modulator with
an ultra­linear low­pass filter and offers a volume control that operates with a 0.5 dB step size. It
incorporates selectable soft ramp and zero crossing transition functions to eliminate clicks and
pops. Standard 50 / 15 μs de­emphasis is available for a 44.1 kHz sample rate for compatibility
with digital audio programs mastered using the 50 / 15 μs pre­emphasis technique.
The analog input of the CODEC is available at audio connector X701. The microphone input is
available at connector X703. The auxiliary output is available at connector X702. And the DAC
output is available at audio connector X704.
The interrupt output from the CODEC is connected to the JADE­D interrupt A1 over 0 Ohm
resistor R735, A2 over 0 Ohm resistor R736 and A3 over 0 Ohm resistor R737. Remove the
corresponding resistor to disconnect the connection which shall not be used !