SPECIFIC FUNCTION
CS
R/C
BUSY EXT/INT DATACLK PWRD SB/BTC
OPERATION
Initiate Conversion and
Output Data Using
Internal Clock
1>0
0
1
0
Output
0
x
Initiates conversion “n”. Data from conversion “n–1”
clocked out on DATA synchronized to 16 clock
pulses ouput on DATACLK.
0
1>0
1
0
Output
0
x
Initiates conversion “n”. Data from conversion “n–1”
clocked out on DATA synchronized to 16 clock
pulses output on DATACLK.
Initiate Conversion and
Output Data Using External
Clock
1>0
0
0
1>0
1
1
1
1
1
1
1
Input
Input
Input
0
0
x
x
x
x
Initiates conversion “n”.
Initiates conversion “n”.
1>0
Outputs a pulse on SYNC followed by data from
conversion “n” clocked out synchronized to external
DATACLK.
1>0
0
1
0>1
0
0
0
1
1
x
Input
Input
x
0
0
0
x
x
x
Outputs a pulse on SYNC followed by data from
conversion “n–1” clocked out synchronized to
external DATACLK.(1) Conversion “n” in process.
Outputs a pulse on SYNC followed by data from
conversion “n–1” clocked out synchronized to
external DATACLK .(1) Conversion “n” in process.
Incorrect Conversions
Power Down
0
0>1
CS or R/C must be HIGH or a new conversion will
be initiated without time for acquisition.
x
x
x
x
x
x
x
x
x
x
0
1
x
x
Analog circuitry powered. Conversion can proceed.
Analog circuitry disabled. Data from previous
conversion maintained in output registers.
x
x
x
x
x
x
x
x
x
x
x
x
0
1
Serial data is output in Binary Two’s Complement
format.
Selecting Output Format
Serial data is output in Straight Binary format.
NOTE: (1) See Figure 3b for constraints on previous data valid during conversion.
TABLE III. Control Truth Table.
DIGITAL OUTPUT
BINARY TWO’S COMPLEMENT
(SB/BTC LOW)
STRAIGHT BINARY
(SB/BTC HIGH)
HEX
CODE
HEX
CODE
ANALOG INPUT
±3.33V
DESCRIPTION
BINARY CODE
BINARY CODE
Full-Scale Range
±10
±5
0V to 10V 0V to 5V
153µV 76µV
0V to 4V
Least Significant Bit (LSB)
+Full Scale (FS – 1LSB)
Midscale
305µV
153µV
102µV
61µV
9.999695V 4.999847V 3.333231V 9.999847V 4.999924V 3.999939V 0111 1111 1111 1111
7FFF 1111 1111 1111 1111 FFFF
0000 1000 0000 0000 0000 8000
FFFF 0111 1111 1111 1111 7FFF
8000 0000 0000 0000 0000 0000
0V
0V
–153µV
–5V
0V
5V
4.999847V 2.499924V 1.999939V 1111 1111 1111 1111
0V 0V 0V 1000 0000 0000 0000
2.5V
2V
0000 0000 0000 0000
One LSB Below Midscale
–Full Scale
–305µV
–10V
–102µV
–3.333333V
TABLE IV. Output Codes and Ideal Input Voltages.
®
6
ADS7809
BB [ BURR-BROWN CORPORATION ]
