Datasheet

ADR3525/ADR3530/ADR3533/ADR3540/ADR3550 Data Sheet
Rev. 0 | Page 16 of 20
TERMINOLOGY
Dropout Voltage (V
DO
)
Dropout voltage, sometimes referred to as supply voltage
headroom 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 upon the current passing
through the device, it is always specified for a given load current.
In series-mode devices, dropout voltage typically increases
proportionally to load current (see Figure 9 and Figure 10).
Temperature Coefficient (TCV
OUT
)
The temperature coefficient relates the change in output voltage
to the change in ambient temperature of the device, as normalized
by the output voltage at 25°C. This parameter is expressed in
ppm/°C and can be determined by the following equations:
]/[10
)()(
)},(min{)},(max{
6
Cppm
TTTV
TTVTTV
TCV
122
OUT
21
OUT
21
OUT
1
OUT
°
×
−×
−
=
]/[10
)()(
)},(min{)},(max{
6
Cppm
TTTV
TTVTTV
TCV
232
OUT
32
OUT
32
OUT
2
OUT
°
×
−×
−
=
},max{
2OUTOUT1OUT
TCVTCVTCV =
(1)
where:
V
OUT
(T) is the output voltage at Temperature T.
T
1
= −40°C.
T
2
= +25°C.
T
3
= +125°C.
This three-point method ensures that TCV
OUT
accurately
portrays the maximum difference between any of the three
temperatures at which the output voltage of the part is
measured.
Thermally Induced Output Voltage Hysteresis (ΔV
OUT_HYS
)
Thermally induced output voltage hysteresis represents the
change in output voltage after the device is exposed to a
specified temperature cycle. This is expressed as either a shift in
voltage or a difference in ppm from the nominal output.
TCOUTOUTHYSOUT
VCVV
__
)25( −°=Δ
[V]
6
_
_
10
)25(
)25(
×
°
−°
=Δ
CV
VCV
V
OUT
TCOUTOUT
HYSOUT
[ppm]
where:
V
OUT
(25°C) is the output voltage at 25°C.
V
OUT_TC
is the output voltage after temperature cycling.
Long-Term Output Voltage Drift (ΔV
OUT_LTD
)
Long-term output voltage drift refers to the shift in output
voltage after 1000 hours of operation in a constant 50°C
environment. This is expressed as either a shift in voltage or a
difference in ppm from the nominal output.
)()(
_
0
OUT
1
OUTLTDOUT
tVtVV −=Δ
[V]
6
_
10
)(
)()(
×
−
=Δ
0
OUT
0
OUT
1
OUT
LTDOUT
tV
tVtV
V
[ppm]
where:
V
OUT
(t
0
) is the V
OUT
at 50°C at Time 0.
V
OUT
(t
1
) is the V
OUT
at 50°C after 1000 hours of operation
at 50°C.
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 microvolts 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
microvolts per mA, ppm per mA, or ohms of dc output
resistance. This parameter accounts for the effects of self-
heating.
Solder Heat Resistance (SHR) Drift
SHR drift refers to the permanent shift in output voltage
induced by exposure to reflow soldering, expressed in units of
ppm. This is caused by changes in the stress exhibited upon the
die by the package materials when exposed to high tempera-
tures. This effect is more pronounced in lead-free soldering
processes due to higher reflow temperatures.