CS4385(2004) View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS4385
(Rev.:2004)

114 dB, 192 kHz 8-Channel D/A Converter

Cirrus Logic 

CS4385

3.3.5 TDM

The TDM serial audio interface format operates in single, double, or quad-speed mode

and will slave to SCLK at 256 Fs. Data is received most significant bit first on the first

SCLK after an LRCK transition and is valid on the rising edge of SCLK. LRCK identifies

the start of a new frame and is equal to the sample rate, Fs. LRCK is sampled as valid on

the rising SCLK edge preceding the most significant bit of the first data sample and must

be held valid for one SCLK period. Each time slot is 32 bits wide, with the valid data sam-

ple left justified within the time slot with the remaining bits being zero padded.

LRCK

256 clks

SCLK

SDIN1

LSB MSB

LSB MSB

LSB MSB

LSB MSB

LSB MSB

LSB MSB

LSB MSB

LSB MSB

LSB

DAC_A1

DAC_A2

DAC_A3

DAC_A4

DAC_B1

DAC_B2

DAC_B3

DAC_B4

32 clks

32 clks

32 clks

32 clks

32 clks

32 clks

32 clks

32 clks

Data

MSB

LSB

zero

Figure 19. Format 12 - TDM Mode

3.4 Oversampling Modes

The CS4385 operates in one of three oversampling modes based on the input sample rate. Mode

selection is determined by the M4, M3 and M2 pins in hardware mode or the FM bits in software

mode. Single-Speed mode supports input sample rates up to 50 kHz and uses a 128x oversam-

pling ratio. Double-Speed mode supports input sample rates up to 100 kHz and uses an over-

sampling ratio of 64x. Quad-speed mode supports input sample rates up to 200 kHz and uses

an oversampling ratio of 32x.

The auto-speed mode detect feature allows for the automatic selection of speed mode based off

of the incoming sample rate. This allows the CS4385 to accept a wide range of sample rates

with no external intervention necessary. The auto-speed mode detect feature is available in both

hardware and software mode.

3.5 Interpolation Filter

To accommodate the increasingly complex requirements of digital audio systems, the CS4385

incorporates selectable interpolation filters for each mode of operation. A “fast” and a “slow” roll-

off filter is available in each of Single, Double, and Quad Speed modes. These filters have been

designed to accommodate a variety of musical tastes and styles. The FILT_SEL bit is used to

select which filter is used (see the Register Description section for more details).

When in hardware mode, only the “fast” roll-off filter is available.

Filter specifications can be found in Section 2, and filter response plots can be found in Figures

28 to 51.

DS671A1

23

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