6

LTC1090

1090fc

PI FU CTIO S

#

PIN

FUNCTION

DESCRIPTION

1-8

CH0 to CH7

Analog Inputs

The analog inputs must be free of noise with respect to AGND.

9

COM

Common

The common pin defines the zero reference point for all single ended inputs. It must be free

of noise and is usually tied to the analog ground plane.

10

DGND

Digital Ground

This is the ground for the internal logic. Tie to the ground plane.

11

AGND

Analog Ground

AGND should be tied directly to the analog ground plane.

12

Negative Supply

13,14

Reference Inputs

The reference inputs must be kept free of noise with respect to AGND.

15

CS

Chip Select Input

A logic low on this input enables data transfer.

16

Digital Data Output

The A/D conversion result is shifted out of this output.

17

Data Input

The A/D configuration word is shifted into this input.

18

SCLK

Shift Clock

This clock synchronizes the serial data transfer.

19

ACLK

A/D Conversion Clock

This clock controls the A/D conversion process.

20

Positive Supply

This supply must be kept free of noise and ripple by bypassing directly to the analog ground

plane.

BLOCK DIAGRA

17

16

SCLK

18

LTC1090 • BD01

CH0

1

CH1

2

CH2

3

CH3

4

CH4

5

CH5

6

CH6

7

CH7

8

COM

9

20

INPUT SHIFT

REGISTER

OUTPUT

SHIFT

REGISTER

CS

15

ACLK

19

CONTROL

AND

TIMING

10-BIT

SAR

SAMPLE

AND HOLD

ANALOG

INPUT

MUX

COMP

REF –

13

10-BIT

CAPACITIVE

DAC

REF+

V–

12

AGND

11

DGND

10

14