adr391 Analog Devices, Inc., adr391 Datasheet - Page 8

• Manufacturer Part Number: adr391
• Description: Micropower, Low Noise Precision Voltage References With Shutdown
• Manufacturer: Analog Devices, Inc.

ADR390/ADR391/ADR392/ADR395
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:
where:
V
V
V
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.
where:
V
V
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.
O
O
O
O
O
(25°C) = V
( T
( T
(T
(T
∆V
V
TCV
∆
1
2
0
1
) = V
) = V
) = V
) = V
O_HYS
V
O
O
= V
O
[
ppm
[
= V
O
O
O
O
ppm
at Temperature 1
at Temperature 2
at 25°C at Time 0
at 25°C after 1,000 hours operation at 25°C
O
O
( t
O
]
at 25°C
0
(25°C) – V
=
) – V
/
°
⎛
⎜
⎜
⎝
C
V
]
=
O
O
( t
( )
V
t
V
1
0
)
O
O
V
(
–
O_TC
( )
25
O
t
V
0
( )
T
°
O
C
2
( )
t
)
1
×
–
V
(
×
T
O
10
2
( )
–
T
6
1
T
⎞
⎟
⎟
⎠
1
)
×
10
6
Rev. F | Page 8 of 20
where:
V
V
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.
O
O_TC
(25°C) = V
V
–100
–150
= V
–50
150
100
O_HYS
50
0
Figure 2. ADR391 Typical Long-Term Drift over 1,000 Hours
to –40°C to +125°C and back to +25°C
0
O
at 25°C after a temperature cycle from + 25°C
[
100
ppm
O
at 25°C
]
200
=
V
O
300
(
V
25
O
°
400
(
C
TIME (Hours)
25
)
–
°
500
C
V
)
O_TC
600
×
10
700
6
800
900
1000