AIC1993 Datasheet, PDF (7/8 Pages) Analog Intergrations Corporation – Linear Fan Control Driver IC

AIC1993
APPLICATION INFORMATIONS
INPUT-OUTPUT CAPACITORS
Linear regulators require input and output ca-
pacitors to maintain stability. Input ceramic ca-
pacitor at 2.2µF with a 2.2uF output ceramic ca-
pacitor is recommended.
EN
EN is used to make system enable and disable. It
supply to output voltage in shutdown logic mode of
fan control.
VSET
The output voltage control pin has 1.6 Time be-
come the output voltage. Voltage limilt form 0V
to 3.125 V like to feedback control resistance in
internal R1 and R2 modulation.
POWER DISSIPATION
The maximum power dissipation of AIC1993
depends on the thermal resistance of its case
and circuit board, the temperature difference be-
tween the die junction and ambient air, and the
rate of airflow. The rate of temperature rise is
greatly affected by the mounting pad configura-
tion on the PCB, the board material, and the
ambient temperature. When the IC mounting
with good thermal conductivity is used, the junc-
tion 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:
PMAX = ^{(TJ − TA)}
(RθJB + RθBA)
Where T_J-T_A is the temperature difference be-
tween the die junction and the surrounding air,
Rθ_JB is the thermal resistance of the package,
and Rθ_BA is the thermal resistance through the
PCB, copper traces, and other materials to the
surrounding air.
As a general rule, the lower temperature is, the
better reliability of the device is. So the PCB
mounting pad should provide maximum thermal
conductivity to maintain low device temperature.
GND pin performs a dual function of providing an
electrical connection to ground and channeling
heat away. Therefore, connecting the GND pin to
ground with a large pad or ground plane would
increase the power dissipation and reduce the
device temperature.
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