CS5397 datasheet(19/40 Pages) CIRRUS

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CS5396 CS5397

DS229PP2

formats include: inverted output, psychoacoustic

output (16-bit, 18-bit, 20-bit), and low group delay

output.

Psychoacoustic Filter

The CS5396/97 includes a programmable 10 tap

digital filter which can be used to perform psycho-

acoustic noise-shaping of the audio spectrum if

desired. The filter can implement a variety of 16-

bit, 18-bit, or 20-bit noise-shaped responses by

setting the digital filter coefficients. Further dis-

cussion of the psychoacoustic filter can be found

in Appendix C.

Appendix B discusses an application using the psy-

choacoustic filter independently of the A/D con-

verter function. In this mode, SDATA2 becomes an

input to the psychoacoustic filter stage and

SDATA1 is the digital audio output.

Low Group Delay Filter

The characteristics of the low group delay filter are

shown in Figures 17 - 24.

µC Interface Formats

The device supports either SPI or I2C interface for-

mats. The CS5396/97 monitors the state of CS dur-

ing power-up and will configure to an SPI interface

if the pin is held low. Conversely, if the pin is held

high, the port will configure to a I2C interface.

SPI Mode

In SPI mode, CS is the chip select signal, CCLK is

the µC bit clock and CDIN is the input data line

from the microcontroller. Notice that it is not pos-

sible to read the CS5396/97 registers in SPI mode

due to the lack of a data output pin.

To write to a register, bring CS low. The first 7 bits

on CDIN are the chip address, and must be zero.

The eighth bit is a read/write indicator (R/W)

which must be low.

The next 8 bits form the Memory Address Pointer

(MAP), which is set to the address of the register

that is to be updated. The next 8 bits are the data

which will be placed into the register designated by

the MAP.

The CS5396/97 has a MAP auto increment, which

will increment the MAP after each byte is written,

allowing block writes of successive registers.

I2C Mode

In I2C mode, CDIN is a bidirectional data line.

Data is clocked into and out of the part by CCLK.

The eighth bit of the address byte is the R/W bit

(high for a read, low for a write). If the operation is

a write, the next byte is the Memory Address Point-

er which selects the register to be read or written. If

the operation is a read, the contents of the register

pointed to by the Memory Address Pointer will be

output. MAP allows successive reads or writes of

consecutive registers. Each byte is separated by an

acknowledge bit. Use of the I2C bus compatible in-

terface requires a license from Philips. I2C bus in a

registered trademark of Philips Semiconductors.

Establishing the Chip Address in I

2C Mode

Connecting SDATA1 pin and CS to 5 volts during

power-up will set the device to the Control Port and

I2C mode. However, the control port will not re-

spond to CCLK and CDATA until the hold on the

SDATA1 pin is released. The chip address can be

set by:

1) Release the hold on the SDATA1 pin of the de-

vice to be addressed.

2) Program the chip address and set the Address

Enable bit, addren, which will prevent further

communication to this device without the cor-

rect address.

3) Repeat steps 1 and 2 for the remaining devices

on the bus.

ANALOG CONNECTIONS - ALL MODES

Figure 1 shows the analog input connections. The

analog inputs are presented differentially to the

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