AD7769

–16–

REV. A

Figure 31. Multichannel Inputs

Multichannel Expansion

In some applications, more than two analog input channels are

required to be converted by the ADC. Figure 31 shows a circuit

configuration for such an application. The ADG528A is a

latched, B-channel analog multiplexer that is ideally suited for

this application since it is specified for single supply operation

(+12 V

±10%).

The

CS, ADC/DAC and WR inputs of the AD7769 are gated to

drive the

WR input of the ADG528A. The multiplexer input

signal is selected on the falling edge of the

WR pulse while the

signal is latched on the rising edge. Also, on the rising edge of

WR, the AD7769 ADC starts conversion. Therefore, the output

signal of the multiplexer must have settled to within 8-bits over

the duration of the

WR pulse (see ADC Conversion Cycle sec-

ADG528A thus determines the width of the

WR pulse.

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

28-Lead Plastic DIP

(N-28)

28-Lead Plastic Leaded Chip Carrier

(P-28A)