LTC1863/LTC1867

7

18637f

PI FU CTIO S

CHO-CH7/COM (Pins 1-8): Analog Input Pins. Analog

inputs must be free of noise with respect to GND. CH7/

COM can be either a separate channel or the common

minus input for the other channels.

REFCOMP (Pin 9): Reference Buffer Output Pin. Bypass to

GND with 10

µF tantalum capacitor in parallel with 0.1µF

ceramic capacitor (4.096V Nominal). To overdrive

used as an external reference buffer input for improved

accuracy and drift. Bypass to GND with 2.2

µF tantalum

capacitor in parallel with 0.1

µF ceramic capacitor.

CS/CONV (Pin 11): This input provides the dual function

of initiating conversions on the ADC and also frames the

serial data transfer.

SCK (Pin 12): Shift Clock. This clock synchronizes the

serial data transfer.

SDO (Pin 13): Digital Data Output. The A/D conversion

result is shifted out of this output. Straight binary format

for unipolar mode and two’s complement format for

bipolar mode.

SDI (Pin 14): Digital Data Input Pin. The A/D configuration

word is shifted into this input.

GND (Pin 15): Analog and Digital GND.

GND with 10

µF tantalum capacitor in parallel with 0.1µF

ceramic capacitor.

TEST CIRCUITS

TYPICAL CO

ECTIO

DIAGRA

CH0

CH1

CH2

CH3

CH4

CH5

CH6

CH7/COM

GND

SDI

SDO

SCK

CS/CONV

REFCOMP

LTC1863/

LTC1867

–

+

+

DIGITAL

I/O

5V

4.096V

10

µF

2.2

µF

2.5V

±2.048V

DIFFERENTIAL

INPUTS

4.096V

SINGLE-ENDED

INPUT

18637 TCD

3k

(A) Hi-Z TO VOH AND VOL TO VOH

3k

5V

DN

DN

(B) Hi-Z TO VOL AND VOH TO VOL

18637 TC01

3k

(A) VOH TO Hi-Z

3k

5V

DN

DN

(B) VOL TO Hi-Z

18637 TC02

Load Circuits for Access Timing

Load Circuits for Output Float Delay