CS5542 CS5543

18

DS109PP2

Conversion Coding

Each of the channels of the CS5543 outputs a 24-

bit conversion data word. The word includes a sign

bit along with 21 additional data bits, an Oscillation

Detect flag (OD), and an odd parity bit. The format

of the data conversion word is shown in Figure 6.

The OD bit is set whenever the modulator in the

CS5542 is overranged to the point of making it lose

stability. Under this condition the output data can

be erroneous. The OD bit can be set whenever the

input magnitude exceeds the full scale point by

greater than 5%. The OD bit will be cleared when-

ever the modulator input comes back into proper

range.

Table 5 illustrates the output coding for the

CS5542/CS5543 chip set. Positive current means

that current is flowing into the INL (INR) pin and

produces a positive output code.

CS5543 Serial Data Interface

The serial data interface on the CS5543 has four in-

put signals and four output signals. Data read from

the CS5543 is output from the DATAOUT[3:0]

pins. DATAOUT[0] outputs data from channels 0

and 4; DATAOUT[1] outputs data from channels 1

and 5; DATAOUT[2] outputs data from channels 2

and 6; and DATAOUT[3] outputs data from chan-

nels 3 and 7. Information from DATAOUT[0] is

output beginning with the sign bit of channel 0 and

ends with the parity (odd) bit of channel 4. Data

out of the other DATAOUT pins follows the same

convention.

In a system, multiple CS5543s are connected with

the DATAOUT pins of one CS5543 connected to

the

DATAIN

pins

of

the

next

CS5543.

DATAOUT[3:0] lines will change immediately af-

ter the rising edge of DATACLK, and be latched

into the DATAIN[3:0] pins on the next rising edge

of DATACLK.

A timing diagram which shows eight channels of

data transfer from one CS5543 to another is shown

in Figure 5.

The data which is transmitted either to or from the

series-connected CS5543s is synchronized by the

FRAME signal. FRAME should be a pulse, one

CLKIN cycle wide, generated by falling edges of

2

23

2

22

2

1

2

0

Sign

2

21

2

20

MSB

LSB OD Parity

2

2

Figure 6. Data Conversion Word Format

Note 1 Positive Full Scale is current going into the modulator.

is always positive in magnitude and will be the absolute value of the current going into either INL/INR or ICAL

Table 5. Output Coding for CS5542/CS5543.

Bipolar Input Current

Output Code (Sign and 21 Data Bits)

1

0

0000

0000

0000

0000

0000

Zero Input

0

0

0000

0000

0000

0000

0000

Negative Full Scale

1

1

1111

1111

1111

1111

1111