AD581

Rev. C | Page 7 of 12

The error band which is guaranteed with the AD581 is the

maximum deviation from the initial value at +25°C; this error

band is of more use to a designer than one which simply guarantees

the maximum total change over the entire range (that is, in the

latter definition, all of the changes could occur in the positive

direction). Thus, with a given grade of the AD581, the designer

can easily determine the maximum total error from initial toler-

ance plus temperature variation (for example, for the AD581T, the

initial tolerance is ±10 mV, the temperature error band is ±15 mV,

thus the unit is guaranteed to be 10.000 V ±25 mV from −55°C

to +125°C).

OUTPUT CURRENT CHARACTERISTICS

The AD581 has the capability to either source or sink current

and provide good load regulation in either direction, although

it has better characteristics in the source mode (positive current

into the load). The circuit is protected for shorts to either positive

supply or ground. The output voltage vs. output current charac-

teristics of the device are shown in Figure 6. Source current

is displayed as negative current in the figure; sink current is

positive. Note that the short-circuit current (that is, 0 V output)

is about 28 mA; when shorted to +15 V, the sink current goes to

about 20 mA.

–20

–15

–10

–5

0

5

10

15

20

14

12

10

8

6

4

2

0

OUTPUT CURRENT (mA)

SOURCE

SINK

Figure 6. Output Voltage vs. Sink and Source Current

DYNAMIC PERFORMANCE

Many low power instrument manufacturers have been in-

creasingly concerned with the turn-on characteristics of the

components used in their systems. Fast turn-on components often

enable the end user to keep power off when not needed, and yet

respond quickly when the power is turned on for operation.

Figure 7 displays the turn-on characteristic of the AD581. This

characteristic is generated from a cold start operation and repre-

sents the true turn-on waveform after an extended period with

the supplies off. The figure shows both the coarse and fine transient

characteristics of the device; the total settling time to within

±10 mV is about 180 μs, and there is no long thermal tail

appearing after the point.

0

50

100 150 200 250

12V

11V

10V

20V

10V

0V

10.03V

10.02V

10.01V

10.00V

SETTLING TIME (µs)

Figure 7. Output Settling Characteristic

1000

1

10

1M

FREQUENCY (Hz)

100

1k

10k

100k

10

100

NOISE SPECTRAL DENSITY (nV/ Hz)

TOTAL NOISE (µV rms) UP

TO SPECIFIED FREQUENCY

Figure 8. Spectral Noise Density and Total rms Noise vs. Frequency

1000

500

TEMPERATURE (°C)

–50

–55

–40 –30 –20 –10 0

10 20 30 40 50 60 70 80 90 100 110 120 125

900

800

700

600

1.5µA/°C

Figure 9. Quiescent Current vs. Temperature