AD1582/AD1583/AD1584/AD1585

–12–

REV. D

TURN-ON TIME

Many low power instrument manufacturers are becoming increas-

ingly concerned with the turn-on characteristics of the components

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

the end user to save power by keeping power off when it is not

needed. Turn-on settling time is defined as the time required, after

the application of power (cold start), for the output voltage to

reach its final value within a specified error. The two major factors

affecting this are the active circuit settling time and the time

required for the thermal gradients on the chip to stabilize.

Figure 12a shows the turn-on settling and transient response test

circuit. Figure 12b shows the turn-on characteristic of the

AD1582. This characteristic is generated from cold-start operation

and represents the true turn-on waveform after power-up.

Figure 12c shows the fine settling characteristics of the AD1582.

Typically, the reference settles to within 0.1% of its final value

in about 100

µs.

The device can momentarily draw excessive supply current

Power supply resistance must be low enough to ensure reliable

turn-on. Fast power supply edges minimize this effect.

0V OR 10V

0V TO 10V

5V OR 10V

0V OR 5V

0.22 F

DUT

0.22 F

10k

10k

1

Figure 12a. Turn-On/Transient Response Test Circuit

10

0%

100

90

20 s

5V

20 s

1V

Figure 12b. Turn-On Characteristics

10

0%

100

90

20 s

5V

20 s

1mV

Figure 12c. Turn-On Settling

DYNAMIC PERFORMANCE

Many A/D and D/A converters present transient current loads

to the reference, and poor reference response can degrade the

converter’s performance. The AD1582/AD1583/AD1584/AD1585

family of references provides superior static and dynamic line

and load regulation. Since these series references are capable of

both sourcing and sinking large current loads, they exhibit

excellent settling characteristics.

Figure 13 displays the line transient response for the AD1582.

The circuit used to perform such a measurement is shown in

Figure 12a, where the input supply voltage is toggled from 5 V

to 10 V and the input and output capacitors are each 0.22

µF.

Figures 14 and 15 show the load transient settling characteristics

for the AD1582 when load current steps of 0 mA to +5 mA

and 0 mA to –1 mA are applied. The input supply voltage

remains constant at 5 V, the input decoupling and output load

capacitors are 4.7

µF and 1 µF, respectively, and the output current

is toggled. For both positive and negative current loads, the

reference responses settle very quickly and exhibit initial voltage

spikes less than 10 mV.

10

0%

100

90

50 s

5V

50 s

200mV

Figure 13. Line Transient Response

10

0%

100

90

20 s

5V

20 s

5mV

Figure 14. Load Transient Response (0 mA to 5 mA Load)

10

0%

100

90

20 s

5V

20 s

5mV

Figure 15. Load Transient Response (0 mA to –1 mA Load)