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)

305

µV

153

µV

102

µV

153

µV76µV61µV

+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

–305

µV

–153

µV

–102

µV

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