Datasheet
ADS7809
7
SBAS017C
www.ti.com
ANALOG INPUT
SPECIFIC FUNCTION CS R/C BUSY EXT/INT DATACLK PWRD SB/BTC OPERATION
Initiate Conversion and 1 > 0 0 1 0 Output 0 x Initiates conversion “n”. Data from conversion “n – 1”
Output Data Using clocked out on DATA synchronized to 16 clock
Internal Clock pulses output 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.
1 > 0 0 1 1 Input 0 x Initiates conversion “n”.
0 1 > 0 1 1 Input 0 x Initiates conversion “n”.
1 > 0 1 1 1 Input x x Outputs a pulse on SYNC followed by data from
conversion “n” clocked out synchronized to external
DATACLK.
1 > 0 1 0 1 Input 0 x Outputs a pulse on SYNC followed by data from
conversion “n – 1” clocked out synchronized to
external DATACLK.
(1)
Conversion “n” in process.
0 0 > 1 0 1 Input 0 x 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 0 0 0 > 1 x x 0 x
CS
or
R/C
must be HIGH or a new conversion will
be initiated without time for acquisition.
Power-Down x x x x x 0 x Analog circuitry powered. Conversion can proceed.
x x x x x 1 x Analog circuitry disabled. Data from previous
conversion maintained in output registers.
Selecting Output Format x x x x x x 0
Serial data is output in Binary Two’s Complement format.
x x x x x x 1 Serial data is output in Straight Binary format.
NOTE: (1) See Figure 3b for constraints on previous data valid during conversion.
Initiate Conversion and
Output Data Using External
Clock
TABLE III. Control Truth Table.
BINARY TWO’S COMPLEMENT STRAIGHT BINARY
(SB/BTC LOW) (SB/BTC HIGH)
DIGITAL OUTPUT
TABLE IV. Output Codes and Ideal Input Voltages.
HEX HEX
DESCRIPTION BINARY CODE CODE BINARY CODE CODE
Full-Scale Range ±10 ±5 ±3.33V 0V to 10V 0V to 5V 0V to 4V
Least Significant Bit (LSB)
305µV 153µV 102µV 153µV76µV61µV
+Full Scale (FS – 1LSB)
9.999695V 4.999847V 3.333231V 9.999847V 4.999924V 3.999939V 0111 1111 1111 1111 7FFF 1111 1111 1111 1111 FFFF
Midscale 0V 0V 0V 5V 2.5V 2V 0000 0000 0000 0000 0000 1000 0000 0000 0000 8000
One LSB Below Midscale
–305µV –153µV –102µV 4.999847V 2.499924V 1.999939V 1111 1111 1111 1111 FFFF 0111 1111 1111 1111 7FFF
–Full Scale –10V –5V –3.333333V 0V 0V 0V 1000 0000 0000 0000 8000 0000 0000 0000 0000 0000