Datasheet
V
HYS
=
lV
REF1
-
V
REF2
l
V
REF
x 10
6
ppm
-40
o
C
V
REF1
Time
V
REF2
25
o
C
125
o
C
LM4030
SNVS552B –MARCH 2008–REVISED APRIL 2013
www.ti.com
Figure 23. Reverse Dynamic Impedance vs C
OUT
As with other regulators, an external capacitor reduces the amplitude of the V
REF
transient when a sudden
change in loading takes place. The capacitor should be placed as close to the part as possible to reduce the
effects of unwanted board parasitics.
THERMAL HYSTERESIS
Thermal hysteresis is the defined as the change in output voltage at 25°C after some deviation from 25°C. This
is to say that thermal hysteresis is the difference in output voltage between two points in a given temperature
profile. An illustrative temperature profile is shown in Figure 24.
Figure 24. Illustrative Temperature Profile
This may be expressed analytically as the following:
where
• V
HYS
= Thermal hysteresis expressed in ppm
• V
REF
= Nominal preset output voltage
• V
REF1
= V
REF
before temperature fluctuation
• V
REF2
= V
REF
after temperature fluctuation (2)
The LM4030 features a low thermal hysteresis of 75 ppm (typical) from -40°C to 125°C after 8 temperature
cycles.
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