r
ea tors
in la
L u
eg
R
Input Capacitor
(C
I
, 0.1 µF to 10 µF). This is necessary
either when the input line includes inductance or when the
wiring is long.
Output Capacitor
(C
O
,
≥
47 µF). This device is de-
signed for use with a very low ESR output capacitor such
as a ceramic capacitor. Output oscillation may occur with
an ESR greater than 500 mΩ.
Output Voltage Adjustable Resistors
(R1 and R2).
The output voltage can be adjusted by R1 and R2. 10 kΩ
or 11 kΩ for R2 is recommended.
R1 = (V
O
– V
ref
)/(V
ref
/R2)
Soft-Start Capacitor
(C
SS
). This capacitor between V
O
and ADJ will set up starting time.
ENABLE Input.
The ENABLE (control) input features
an internal pull-down resistor. Leaving this input open
causes the output to turn off.
Determination of DC Input Voltage.
The minimum
input voltage V
I
(min) should be higher than the sum of the
fixed output voltage and the maximum rated dropout
voltage.
Overcurrent Protection.
The SI-3000LLSL series has
a built-in fold-back type overcurrent protection circuit,
which limits the output current at a start-up mode. It thus
cannot be used in applications that require current at the
start-up mode such as:
(1) constant-current load,
(2) power supply with positive and negative outputs to
common load (a center-tap type power supply), or
(3) raising the output voltage by putting a diode or a
resistor between the device ground and system ground.
Thermal Protection.
Circuitry turns off the pass
transistor when the junction temperature rises above 135°C.
It is intended only to protect the device from failures due to
excessive junction temperatures and should not imply that
output short circuits or continuous overloads are permitted.
SI-3010LLSL
1.5 A, Ultra-Low-Dropout,
1~3.3 V Regulator
APPLICATIONS INFORMATION
Heat Radiation and Reliability.
The reliability of the
device is directly related to the junction temperature (T
J
) in
its operation. Accordingly, careful consideration should be
given to heat dissipation.
The inner frame on which the pass transistor is mounted is
connected to terminals 7 and 8. Therefore, it is very
effective for heat radiation to enlarge the copper area that is
connected to these terminals. The graph illustrates the
effect of the copper area on the junction-to-ambient thermal
resistance (R
θJA
).
The junction temperature (T
J
) can be determined from
either of the following equations:
T
J
= (P
D
× R
θJA
) + T
A
or
T
J
= (P
D
× R
θJL
) + T
L
where P
D
= I
O
× (V
I
– V
O
),
T
L
is the temperature of lead 8, and
R
θJL
= 36°C/W.
Parallel Operation.
Parallel operation to increase load
current is not permitted.
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