SPI-8001TW-TL ALLEGRO [Allegro MicroSystems], SPI-8001TW-TL Datasheet - Page 7

• Manufacturer Part Number: SPI-8001TW-TL
• Description: Dual 1.5 A, DC/DC Step-Down Converter
• Manufacturer: ALLEGRO [Allegro MicroSystems]

Overcurrent Protection. The SPI-8000TW 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.
Determination of DC Input Voltage. The minimum
value of dc input voltage is V
maximum value is 20 V when the output value is more than
2 V, derated linearly to 10 V when the output is 1 V.
Parallel Operation. Parallel operation to increase load
current is not permitted.
Thermal Protection. Circuitry turns off the device
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
O
+ 3 V. The recommended
APPLICATIONS INFORMATION (cont.)
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 exposed pad. Therefore, it is very
effective for heat radiation to enlarge the copper area that is
connected to the pad. The graph on page 2 illustrates 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
and
where V
is the output current ηx is efficiency (%) and V
diode forward voltage SFPB-66 (0.45 V, I
P
D
=
.
O
V
is the output voltage, V
O
θJA
).
I
O
Layout Guideline
T
T
J
J
100
= (P
= (P
ηx
R
Step-Down Converter
θJL
D
D
–
Dual 1.5 A, DC/DC
= 9°C/W
× R
J
× R
) can be determined from
1
θJA
θJL
SPI-8001TW
–
IN
) + T
) + T
V
is the input voltage, I
F
A
L
I
O
O
= 1A).
1
F
–
is the
V
J
V
) in its
IN
O
O
7