Datasheet

ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550 Data Sheet
Rev. B | Page 30 of 37
TERMINOLOGY
Dropout Voltage (V
DO
)
Dropout voltage, sometimes referred to as supply voltage head-
room or supply output voltage differential, is defined as the
minimum voltage differential between the input and output such
that the output voltage is maintained to within 0.1% accuracy.
V
DO
= (V
IN
− V
OUT
)
min
|I
L
= constant
Because the dropout voltage depends on the current passing
through the device, it is always specified for a given load current.
In series mode devices, the dropout voltage typically increases
proportionally to the load current (see Figure 5, Figure 18,
Figure 32, Figure 45, Figure 58, and Figure 71).
Line Regulation
Line regulation refers to the change in output voltage in response
to a given change in input voltage and is expressed in percent
per volt, ppm per volt, or μV per volt change in input voltage.
This parameter accounts for the effects of self heating.
Load Regulation
Load regulation refers to the change in output voltage in response
to a given change in load current and is expressed in μV per mA,
ppm per mA, or ohms of dc output resistance. This parameter
accounts for the effects of self heating.
Solder Heat Resistance (SHR) Shift
SHR shift refers to the permanent shift in output voltage that is
induced by exposure to reflow soldering and is expressed as a
percentage of the output voltage. This shift is caused by changes
in the stress exhibited on the die by the package materials when
these materials are exposed to high temperatures. This effect is
more pronounced in lead-free soldering processes due to higher
reflow temperatures. SHR is calculated after three solder reflow
cycles to simulate the worst case conditions when assembling a
two-sided PCB with surface mount components with one addi-
tional rework cycle. The reflow cycles use the JEDEC standard
reflow temperature profile.
Temperature Coefficient (TCV
OUT
)
The temperature coefficient relates the change in the output
voltage to the change in the ambient temperature of the device, as
normalized by the output voltage at 25°C. The TCV
OUT
for the
ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550
A grade and B grade is fully tested over three temperatures: −40°C,
+25°C, and +125°C. The TCV
OUT
for the C grade is fully tested
over three temperatures: 0°C, +25°C, and +70°C. This parameter
is specified using two methods. The box method is the most
common method and accounts for the temperature coefficient
over the full temperature range, whereas the bowtie method
calculates the worst case slope from +25°C and is therefore
more useful for systems which are calibrated at +25°C.
Box Method
The box method is represented by the following equation:
6
10
)()(
)},,({)},,({
×
−×
−
=
132
OUT
321
OUT
321
OUT
OUT
TTTV
TTTVminTTTVmax
TCV
where:
TCV
OUT
is expressed in ppm/°C.
V
OUT
(T
X
) is the output voltage at Temperature T
X
.
T
1
= −40°C.
T
2
= +25°C.
T
3
= +125°C.
This box method ensures that TCV
OUT
accurately portrays the
maximum difference between any of the three temperatures at
which the output voltage of the device is measured.
Bowtie Method
The bowtie method is represented by the following equation:
}
,{
2
1 OUTOUT
OUT
TCVTCV
maxTCV
=
where:
6
23
3232
2
6
2
1
10
)()(
)},({)},({
10
)()(
)},({)},({
×
−×
−
=
×
−×
−
=
TTTV
TTVminTTVmax
TCV
TTTV
TTVminTTVmax
TCV
2OUT
OUTOUT
OUT
12OUT
21OUT21OUT
OUT
TCV
OUT
is expressed in ppm/°C.
V
OUT
(T
X
) is the output voltage at Temperature T
X
.
T
1
= 0°C.
T
2
= +25°C.
T
3
= +70°C.
Thermally Induced Output Voltage Hysteresis (ΔV
OUT_HYS
)
Thermally induced output voltage hysteresis represents the
change in the output voltage after the device is exposed to a
specified temperature cycle. This is expressed as a difference in
ppm from the nominal output.
6
25_
25_225_1
_
10×
−
=∆
°
°°
COUT
COUTCOUT
HYSOUT
V
VV
V
[ppm]
where:
V
OUT1_25°C
is the output voltage at 25°C.
V
OUT2_25°C
is the output voltage after temperature cycling.
Long-Term Stability (ΔV
OUT_LTD
)
Long-term stability refers to the shift in the output voltage versus
time. This is expressed as a difference in ppm from the nominal
output.
6
_
10
)(
)()(
×
−
=∆
0
OUT
0
OUT
1
OUT
LTDOUT
tV
tVtV
V
[ppm]
where:
V
OUT
(t
0
) is the V
OUT
at the starting time of the measurement.
V
OUT
(t
1
) is the V
OUT
at the end time of the measurement.
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