®

ADC76

8

FIGURE 10. Two Methods of Connecting Optional Offset

Adjust.

FIGURE 11. Connecting Optional Gain Adjust.

Adjust the Offset potentiometer until the actual end point

transition voltage occurs at E

voltage values of the input are given in Table I.

Gain—Connect the Gain adjust potentiometer as shown in

Figure 11. Sweep the input through the end point transition

voltage; that should cause an output transition to all bits on

E

point transition voltage occurs at E

Table I details the transition voltage levels required.

CONVERT COMMAND CONSIDERATIONS

Convert command resets the converter whenever taken high.

This insures a valid conversion on the first conversion after

power-up.

Convert command must stay low during a conversion unless

it is desired to reset the converter during a conversion.

OPTIONAL CONVERSION TIME ADJUSTMENT

The ADC76 may be operated with faster conversion times

for resolutions less than 14 bits by connecting the Short

Cycle (pin 32) as shown in Table III. Typical conversion

times for the resolution and connections are indicated.

Resolution (Bits)

16

15

14

13

12

Connect Pin 32 to

Open

Pin 16

Pin 15

Pin 14

Pin 13

Typical Conversion Time

17

µs16µs15µs13µs12µs

TABLE III. Short Cycle Connections for 12- to 16-Bit

Resolutions.

Clock Rate Control may be connected to an external multi-

turn trim potentiometer with a TCR of

±10ppm/°C or less as

shown in Figure 12. The typical conversion time versus the

Clock Rate Control voltage is shown in Figure 13. The effect

of varying the conversion time and the resolution on Linear-

ity Error and Differential Linearity Error is shown in Figure

6.

FIGURE 12. Clock Rate Control, Optional Fine Adjust.

Control Voltage on Pin 23 (V)

0

2

4

6

8

20

15

10

Typical

14-Bit Operation

16-Bit Operation

FIGURE 13. Conversion Time vs Clock Rate Control

Voltage.

180k

Ω

+15VDC

–15VDC

10k

to 100k

Offset Adjust

Ω

Ω

22k

Ω

(b)

1.8M

Ω

27

+15VDC

–15VDC

10k

to 100k

Offset Adjust

Ω

Ω

(a)

Comparator In

27

Comparator In

180k

Ω

R1

R1

270k

Ω

22

+15VDC

–15VDC

10k

to 100k

Gain Adjust

Ω

Ω

Gain Adjust

0.01µF

29

Analog Common

Clock Rate Control

+15VDC

5k

Ω

Internal Clock

Frequency Adjust

23