9

LTC1090

1090fc

TYPICAL PERFOR A CE CHARACTERISTICS

Digital Input Logic Threshold vs

Supply Voltage

Input Channel Leakage Current

vs Temperature

Noise Error vs Reference Voltage

The LTC1090 is a data acquisition component which

contains the following functional blocks:

1. 10-bit successive approximation capacitive

A/D converter

2. Analog multiplexer (MUX)

3. Sample and hold (S/H)

4. Synchronous, full duplex serial interface

5. Control and timing logic

DIGITAL CONSIDERATIONS

1. Serial Interface

The LTC1090 communicates with microprocessors and

other external circuitry via a synchronous, full duplex,

four wire serial interface (see Operating Sequence). The

shift clock (SCLK) synchronizes the data transfer with

each bit being transmitted on the falling SCLK edge

and captured on the rising SCLK edge in both transmit-

ting and receiving systems. The data is transmitted and

received simultaneously (full duplex).

Operating Sequence

(Example: Differential Inputs (CH3 to CH2), Bipolar, MSB First and 10-Bit Word Length)

0.2

0.5

1.0

2.0

15

LTC1090 • TPC21

1.5

0.25

0.75

1.75

1.25

LTC1090 NOISE = 200µV PEAK-TO-PEAK

APPLICATIO S I FOR ATIO

4

0

1

2

3

4

56

7

8

LTC1090 • TPC19

910

–50

100

300

400

500

1000

700

0

50

75

LTC1090 • TPC20

200

800

900

600

–25

25

100

125

GUARANTEED

ON CHANNEL

OFF CHANNELS

LTC1090 • AI01

B9

(SB)

SHIFT A/D RESULT OUT AND

NEW CONFIGURATION WORD IN

B8

B7

B6

B5

B4

B3

B2

B1

B0

SHIFT CONFIGURATION

WORD IN

ODD/

SIGN

SGL/

DIFF

SEL1

CS

15

8

10

SCLK

SEL0 UNI MSBF WL1 WL0

DON’T CARE

DON’T CARE