Datasheet

ADR121/ADR125/ADR127
Rev. B | Page 15 of 20
TERMINOLOGY
Temperature Coefficient
The change in output voltage with respect to operating
temperature change normalized by the output voltage at 25°C.
This parameter is expressed in ppm/°C and can be determined
as follows:
[]
() ()
()( )
6
10
C25
Cppm/ ×
−×°
−
=°
12OUT
1OUT2
UT
O
OUT
TTV
TVTV
TCV
(1)
where:
V
OUT
(25°C) = V
OUT
at 25°C.
V
OUT
(T
1
) = V
OUT
at Temperature 1.
V
OUT
(T
2
) = V
OUT
at Temperature 2.
Line Regulation
The change in the output voltage due to a specified change
in input voltage. This parameter accounts for the effects of
self-heating. Line regulation is expressed in percent per volt,
parts-per-million per volt, or microvolts per voltage 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 microvolts per milliampere,
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 1000 hours at 25°C.
(
)()
[]
() ()
()
6
10ppm ×
−
=Δ
−
Δ
0OUT
1OUT0OUT
OUT
1
UT
O0OUT
UT
O
tV
tVtV
V
tVtVV
(2)
where:
V
OUT
(t
0
) = V
OUT
at 25°C at Time 0.
V
OUT
(t
1
) = V
OUT
at 25°C after 1000 hours operating at 25°C.
Thermal Hysteresis
The change in 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.
(
)
TCOUTOUTHYSOUT
VVV
__
C25 −°
=
(3)
[]
()
()
6
_
_
10
C25
C25
ppm ×
°
−°
=
OU
T
TCOUT
UT
O
HYSOUT
V
VV
V
where:
V
OUT
(25°C) = V
OUT
at 25°C.
V
OUT_TC
= V
OUT
at 25°C after temperature cycle at +25°C to
−40°C to +125°C and back to +25°C.