8205 Datasheet, PDF (4/8 Pages) Allegro MicroSystems – LOW-DROPOUT REGULATORS . HIGH EFFICIENCY

8205
LOW-DROPOUT
REGULATORS
APPLICATIONS INFORMATION
Linear regulators require input and output capacitors in order to
maintain over-all loop stability. The recommended minimum
value for the input capacitor is 0.1 µF. The output capacitor is
the dominant pole that provides the high-frequency compensa-
tion required for over-all regulator loop stability. These devices
are stable with as little as 1 µF. However, to ensure stable
operation under all conditions and capacitor types, the recom-
mended minimum value is 4.7 µF. The output capacitor may be
partially distributed through the load circuits. However, at least
1 µF should be connected at the regulator using the shortest and
widest foil pattern possible.
The A8205SLH-ADJ requires an external voltage divider to set
up the desired regulated output voltage between 2.0 V and 6.8 V
(V_I ≤ 7 V). The two resistors are chosen such that
V_O = 1.26 (R1 + R2)/R2.
The resistor values are usually as high as possible to maintain
high circuit efficiency, but R2 should be less than 300 kΩ.
INPUT
(7.0 V MAX)
0.1 µF
(MIN)
OUTPUT (2.0 V TO 6.8 V)
1 µF
VR
(MIN)
R1
ENABLE
(ACTIVE HIGH)
R2
(300 kΩ MAX)
Thermal Considerations
These devices are intended to provide more than 150 mA of
continuous current in a very small package. The table on page 2
of this data sheet gives the maximum allowable average output
current for a worst-case printed circuit design (R_θJA = 220°C/W
with a minimum footprint). Performance improvement is easily
accomplished with the addition of 1 square inch of copper at
terminal 2 (R_θJA = 170°C/W).
Dwg. ES-015
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