CS4228 Datasheet, PDF (27/30 Pages) Cirrus Logic – 24-Bit, 96 kHz Surround Sound Codec

CS4228
Mute Control - MUTEC
Pin 15, Output
Function:
The Mute Control pin goes low during the following conditions: power-up initialization, power-down, reset,
no master clock present, or if the master clock to left/right clock frequency ratio is incorrect. The Mute Con-
trol pin can also be user controlled by the MUTEC bit in the DAC Mute2 Control register. Mute Control can
be automatically asserted when 512 consecutive zeros are detected on all six DAC inputs, and automat-
ically deasserted when a single non-zero value is sent to any of the six DACs. The mute on zero function
is controlled by the MUTCZ bit in the DAC Mute2 Control register. The MUTEC pin is intended to be used
as a control for an external mute circuit to achieve a very low noise floor during periods when no audio is
present on the DAC outputs, and to prevent the clicks and pops that can occur in any single supply sys-
tem. Use of the Mute Control pin is not mandatory but recommended.
Differential Analog Inputs — AINR+, AINR- and AINL+, AINL-
Pins 16, 17 and 19, 20, Inputs
Function:
The analog signal inputs are presented deferentially to the modulators via the AINR+/- and AINL+/- pins.
The + and - input signals are 180° out of phase resulting in a nominal differential input voltage of twice the
input pin voltage. These pins are biased to the internal reference voltage of approximately 2.3 V. A pas-
sive anti-aliasing filter is required for best performance, as shown in Figure 5. The inputs can be driven at
-1dB FS single-ended if the unused input is connected to ground through a large value capacitor. A single
ended to differential converter circuit can also be used for slightly better performance.
Internal Voltage Filter - FILT
Pin 18, Output
Function:
Filter for internal circuits. An external capacitor is required from FILT to analog ground, as shown in Figure
5. FILT is not intended to supply external current. FILT+ has a typical source impedance of 250 kΩ and
any current drawn from this pin will alter device performance. Care should be taken during board layout
to keep dynamic signal traces away from this pin.
Analog Power - VA
Pin 21, Input
Function:
Power for the analog and reference circuits. Typically 5.0 VDC.
Analog Ground - AGND
Pin 22, Input
Function:
Analog ground reference.
Analog Output - AOUT1, AOUT2, AOUT3, AOUT4, AOUT5 and AOUT6
Pins 23, 24, 25, 26, 27, 28, Outputs
Function:
Analog outputs from the DACs. The full scale analog output level is specified in the Analog Characteristics
specifications table. The amplitude of the outputs is controlled by the Digital Volume Control registers
VOL6 - VOL1.
DS307PP1
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