AD586

REV. C

–6–

Centigrade; i.e., ppm/

°C. However, because of nonlinearities in

temperature characteristics which originated in standard Zener

references (such as “S” type characteristics), most manufactur-

ers have begun to use a maximum limit error band approach to

specify devices. This technique involves the measurement of the

output at three or more different temperatures to specify an out-

put voltage error band.

Figure 9 shows the typical output voltage drift for the AD586L

and illustrates the test methodology. The box in Figure 9 is

bounded on the sides by the operating temperature extremes,

and on the top and the bottom by the maximum and minimum

output voltages measured over the operating temperature range.

The slope of the diagonal drawn from the lower left to the upper

right corner of the box determines the performance grade of the

device.

Figure 9. Typical AD586L Temperature Drift

Each AD586J, K and L grade unit is tested at 0

°C, +25°C and

+70

°C. Each AD586SQ and TQ grade unit is tested at –55°C,

+25

°C and +125°C. This approach ensures that the variations

of output voltage that occur as the temperature changes within

the specified range will be contained within a box whose diago-

nal has a slope equal to the maximum specified drift. The posi-

tion of the box on the vertical scale will change from device to

device as initial error and the shape of the curve vary. The maxi-

mum height of the box for the appropriate temperature range

and device grade is shown in Figure 10. Duplication of these

results requires a combination of high accuracy and stable tem-

perature control in a test system. Evaluation of the AD586 will

produce a curve similar to that in Figure 9, but output readings

may vary depending on the test methods and equipment utilized.

DEVICE

MAXIMUM OUTPUT CHANGE

GRADE

(mV)

0 C TO +70 C

–40 C TO +85 C

–55 C TO +125 C

AD586J

8.75

AD586K

5.25

AD586L

1.75

AD586M

0.70

AD586A

3.12

AD586B

9.37

AD586S

18.00

AD586T

9.00

Figure 10. Maximum Output Change in mV

In some applications, a varying load may be both resistive and

capacitive in nature, or the load may be connected to the

AD586 by a long capacitive cable.

Figure 7 displays the output amplifier characteristics driving a

1000 pF, 0 to 10 mA load.

Figure 7a. Capacitive Load Transient Response Test Circuit

Figure 7b. Output Response with Capacitive Load

LOAD REGULATION

The AD586 has excellent load regulation characteristics. Figure

8 shows that varying the load several mA changes the output by

a few

µV. The AD586 has somewhat better load regulation per-

formance sourcing current than sinking current.

Figure 8. Typical Load Regulation Characteristics

TEMPERATURE PERFORMANCE

The AD586 is designed for precision reference applications

where temperature performance is critical. Extensive tempera-

ture testing ensures that the device’s high level of performance is

maintained over the operating temperature range.

Some confusion exists in the area of defining and specifying ref-

erence voltage error over temperature. Historically, references

have been characterized using a maximum deviation per degree