ADR390/ADR391/ADR392/ADR395

Rev. F | Page 8 of 20

TERMINOLOGY

Temperature Coefficient

The change of output voltage with respect to operating temp-

erature changes normalized by the output voltage at 25°C. This

parameter is expressed in ppm/°C and can be determined by the

following equation:

[]

()

( )

()

()

6

10

–

25

–

×

×

°

=

°

1

2

O

1

O

2

O

O

T

T

C

V

T

V

T

V

C

/

ppm

TCV

where:

Line Regulation

The change in output voltage due to a specified change in input

voltage. This parameter accounts for the effects of self-heating.

Line regulation is expressed in either percent per volt, parts-

per-million per volt, or microvolts per volt change in input

voltage.

Load Regulation

The change in output voltage due to a specified change in load

current. This parameter accounts for the effects of self-heating.

Load regulation is expressed in either microvolts per milli-

ampere, parts-per-million per milliampere, or ohms of dc

output resistance.

Long-Term Stability

Typical shift of output voltage at 25°C on a sample of parts

subjected to a test of 1,000 hours at 25°C.

∆

[]

()

()

()

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

×

=

∆

6

10

–

0

O

1

O

0

O

O

t

V

t

V

t

V

ppm

V

where:

Thermal Hysteresis

The change of output voltage after the device is cycled through

temperatures from +25°C to –40°C to +125°C and back to

+25°C. This is a typical value from a sample of parts put

through such a cycle.

[]

(

)

()

6

10

25

–

25

×

°

°

=

C

V

V

C

V

ppm

V

O

O_TC

O

O_HYS

where:

to –40°C to +125°C and back to +25°C

NOTES

Input Capacitor

Input capacitors are not required on the ADR39x. There is no

limit for the value of the capacitor used on the input, but a

1 µF to 10 µF capacitor on the input improves transient

response in applications where the supply suddenly changes.

An additional 0.1 µF in parallel also helps reduce noise

from the supply.

Output Capacitor

The ADR39x does not require output capacitors for stability

under any load condition. An output capacitor, typically 0.1 µF,

filters out any low level noise voltage and does not affect the

operation of the part. On the other hand, the load transient

response can improve with the addition of a 1 µF to 10 µF

output capacitor in parallel. A capacitor here acts as a source of

stored energy for a sudden increase in load current. The only

parameter that degrades by adding an output capacitor is the

turn-on time, and it depends on the size of the capacitor

chosen.

–150

150

TIME (Hours)

0

–100

–50

0

50

100

100

200

300

400

500

600

700

1000

900

800

Figure 2. ADR391 Typical Long-Term Drift over 1,000 Hours