AIC1731
DETAILED DESCRIPTIONS OF TECHNICAL TERMS
DROPOUT VOLTAGE (V
DROP
)
The dropout voltage is defined as the difference
between the input voltage and output voltage at
which the output voltage drops 100mV. Below
this value, the output voltage will fall as the input
voltage reduces. It depends on the load current
and junction temperature.
LINE REGULATION
Line regulation is the ability of the regulator to
maintain a constant output voltage as the input
voltage changes. The line regulation is specified
as the input voltage changes from V
IN
= V
OUT
+
1V to V
IN
= 7V and I
OUT
= 1mA.
LOAD REGULATION
Load regulation is the ability of the regulator to
maintain a constant output voltage as the load
current changes. A pulsed measurement with an
input voltage set to V
IN
= V
OUT
+ V
DROP
can
minimize temperature effects. The load regulation
is specified by the output current ranging from
0.1mA to 300mA.
CURRENT LIMIT (I
IL
)
AIC1731 includes a current limiting, which
monitors and controls the maximum output
current if the output is shorted to ground. This
can protect the device from being damaged.
THERMAL PROTECTION
Thermal sensor protects device when the
junction temperature exceeds T
J
= +155ºC. It
signals shutdown logic, turning off pass transistor
and allowing IC to cool down. After the IC’s
junction temperature cools by 15ºC, the thermal
sensor will turn the pass transistor back on.
Thermal protection is designed to protect the
device in the event of fault conditions. For a
continuous operation, do not exceed the absolute
maximum junction-temperature rating of T
J
=
150ºC, or damage may occur to the device.
APPLICATION INFORMATION
INPUT-OUTPUT CAPACITORS
Linear regulators require input and output
capacitors to maintain stability. Input capacitor at
1µF with a 1uF aluminum electrolytic output
capacitor is recommended. To avoid oscillation,
ceramic capacitor is rejected.
NOISE BYPASS CAPACITOR
0.1µF bypass capacitor at BP pin reduces output
voltage noise. And the BP pin has to connect a
capacitor to GND.
POWER DISSIPATION
The maximum power dissipation of AIC1731
depends on the thermal resistance of its case
and circuit board, the temperature difference
between the die junction and ambient air, and
the rate of airflow. The rate of temperature rise is
greatly affected by the mounting pad
configuration on the PCB, the board material,
and the ambient temperature. When the IC
mounting with good thermal conductivity is used,
the junction temperature will be low even when
large power dissipation applies.
The power dissipation across the device is
P = I
OUT
(V
IN
-V
OUT
).
The maximum power dissipation is:
P
MAX
=
(T
J
−
T
A
)
(Rθ
JB
+
Rθ
BA
)
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AIC [ ANALOG INTERGRATIONS CORPORATION ]
