DF1704

9

SBAS099A

RESET

SOFTWARE

HARDWARE

DEFAULT

FUNCTION

(MODE = H)

(MODE = L)

(Software Mode)

Input Data Format Selection

O

O

Standard Format

Input Word Length Selection

O

O

16 Bits

Output Word Length Selection

O

O

16 Bits

LRCIN Polarity Selection

O

O

Left/Right = High/Low

Digital De-Emphasis

O

O

OFF

Soft Mute

O

O

OFF

Digital Attenuation

O

X

0dB, Independent L/R

Sample Rate for

De-Emphasis Function

O

O

44.1 kHz

Filter Roll-Off Selection

O

O

Sharp Roll-Off Selected

CLKO Output Frequency Selection

O

O

Same As XTI Input

Legend: O = User Programmable, X = Not Available.

TABLE III. User-Programmable Functions for Software and

Hardware Mode.

Programmable Functions

The DF1704 includes a number of programmable features,

with most being accessible from either Hardware or Soft-

ware mode. Table III summarizes the user programmable

functions for both modes of operation.

Hardware Mode Controls

With MODE = L, the DF1704 may be configured by

utilizing several user-programmable pins. The following is a

brief summary of the pin functions. Table IV provides more

details on setting the hardware mode controls.

input format and word length.

Pins OW0 and OW1 are used to select the output data word

length.

The DEM pin is used to enable and disable the digital de-

emphasis function. De-emphasis is only available for 32kHz,

44.1kHz, and 48kHz sample rates.

Pins SF0 and SF1 are used to select the sample rate for the

de-emphasis function.

The SRO pin is used to select the digital filter response,

either sharp or slow roll-off.

The MUTE pin is used to enable or disable the soft mute

function.

The CKO pin is used to select the clock frequency seen at

the CLKO pin, either XTI or XTI

÷ 2.

The LRIP pin is used to select the polarity used for the audio

input left/right clock, LRCIN.

Finally, the RESV pin is not used by the current DF1704

design, but is reserved for future use.

Software Mode Controls

With MODE = H, the DF1704 may be configured by

programming four internal registers in software mode. ML

(pin 13), MC (pin 12), and MD (pin 11) make up the 3-wire

software control port, and may be controlled using DSP or

microcontroller general purpose I/O pins, or a serial port.

Table V provides an overview of the internal registers,

labeled MODE0 through MODE3.

t

BCKH

0.5V

DD

0.5V

DD

BCKO

DOL, R

t

BCKL

t

CKWK

t

WCKP

t

BCKP

t

CKDO

0.5V

DD

WCKO

BCKO Period

Delay Time BCKO Falling Edge to WCKO Valid

WCKO Period

Delay Time BCKO Falling Edge to DOL, R Valid

Rising Time of All Signals

Falling Time of All Signals

t

BCKP

t

BCKH

t

BCKL

t

CKWK

t

WCKP

t

CKDO

t

R

t

F

min

typ

1/8 f

S

20ns

20ns

–5ns

–5ns

100ns

100ns

5ns

5ns

7ns

7ns

max

1/256 f

NOTES: (1) Timing measurement reference level is (V

measured from 10% to 90% of IN/OUT signals’ swing. (3) Load capacitance of all signals

are 20pF. (4) Exceptions: f

t

FIGURE 7. Audio Output Data Format.