SI-3011ZD Allegro Microsystems Inc, SI-3011ZD Datasheet - Page 5

• Manufacturer Part Number: SI-3011ZD
• Description: Regulator IC - Low Dropout Voltage (Surface Mount)
• Manufacturer: Allegro Microsystems Inc

Input Capacitor (C
either when the input line includes inductance or when the
wiring is long.
Output Capacitor (C
designed for a use with a very low ESR output capacitor
such as a ceramic capacitor. Output oscillation may occur
with that kind of capacitor.
Output Voltage Adjustable Resistors (R1 and R2).
The output voltage is adjusted by R1 and R2. 10 k or
11 k for R2 is recommended.
For an output voltage of 1.8 V or less, add a 10 k resistor
between ADJ and the junction of R1 and R2.
Determination of DC Input Voltage. The minimum
input voltage V
fixed output voltage and the maximum rated dropout
voltage. If setting the output voltage lower than 2.0 V, the
minimum input voltage should be more than 2.4 V.
Overcurrent Protection. The SI-3000ZD 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.
www.allegromicro.com
I
R1 = (V
(min) should be higher than the sum of the
I
, 0.1 µF to 10 µF). This is necessary
O
O
, > 47 µF). This device is not
– V
ref
)/(V
ref
/R2)
APPLICATIONS INFORMATION
Heat Radiation and Reliability. The reliability of the
IC is directly related to the junction temperature (T
operation. Accordingly, careful consideration should be
given to heat dissipation.
The inner frame on which the integrated circuit is mounted
is connected to the GND terminal (pin 3). Therefore, it is
very effective for heat radiation to enlarge the copper area
that is connected to the GND terminal. The graph illus-
trates the effect of the copper area on the junction-to-
ambient thermal resistance (R
The junction temperature (T
either of the following equations:
or
where P
Parallel Operation. Parallel operation to increase load
current is not permitted.
R
D
JT
= I
= 3°C/W.
O
× (V
T
T
J
I
J
– V
= (P
= (P
O
D
D
) and
× R
J
× R
) can be determined from
1.1~5 V Regulator
JA
).
JA
JT
) + T
) + T
High-Current,
Low-Dropout,
SI-3011ZD
A
T
J
) in its
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