AP1501A-33K5G-U Diodes Inc, AP1501A-33K5G-U Datasheet - Page 10
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AP1501A-33K5G-U
Manufacturer Part Number
AP1501A-33K5G-U
Description
Switching Converters, Regulators & Controllers PWM SYN 150KHz 5A 4.5-40V 3.3V
Manufacturer
Diodes Inc
Datasheet
1.AP1501A-50K5L-13.pdf
(14 pages)
Specifications of AP1501A-33K5G-U
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Functional Description
Pin Functions
+V
This is the positive input supply for the IC switching regulator. A suitable
input bypass capacitor must be present at this pin to minimize voltage
transients and to supply the switching currents needed by the regulator.
Ground
Circuit ground.
Output
Internal switch. The voltage at this pin switches between (+V
and approximately – 0.5V, with a duty cycle of approximately
V
copper area connected to this pin should be kept a minimum.
Feedback
Senses the regulated output voltage to complete the feedback loop.
ON/OFF
Allows the switching regulator circuit to be shutdown using logic level
signals thus dropping the total input supply current to approximately
150uA. Pulling this pin below a threshold voltage of approximately
1.3V turns the regulator on, and pulling this pin above 1.3V (up to a
maximum of 40V) shuts the regulator down. If this shutdown feature is
not needed, the ON/OFF pin can be wired to the ground pin or it can be
left open, in either case the regulator will be in the ON condition.
Thermal Considerations
The AP1501A is available in two packages, a 5-pin surface mount
TO-263 and TO-220.
The TO-220 package needs a heat sink under most conditions. The size
of the heat sink depends on the input voltage, the output voltage, the
load current and the ambient temperature. The AP1501A junction
temperature rises above ambient temperature for a 5A load and different
input and output voltages. The data for these curves was taken with the
AP1501A (TO-220 package) operating as a buck switching regulator in
an ambient temperature of 25
numbers are all approximate and there are many factors that can affect
these temperatures. Higher ambient temperatures require more heat
sinking.
The TO-263 surface mount package tab is designed to be soldered to
the copper on a printed circuit board. The copper and the board are the
heat sink for this package and the other heat producing components,
such as the catch diode and inductor. The PC board copper area that
the package is soldered to should be at least 0.8 in
have 2 or more square inches of 2 oz. Additional copper area improves
the thermal characteristics, but with copper areas greater than
approximately 6 in
realized. If further thermal improvements are needed, double sided,
multilayer PC boards with large copper areas and/or airflow are
recommended.
AP1501A Rev. 10
DS31191
OUT
IN
/ V
IN
. To minimize coupling to sensitive circuitry, the PC board
2
, only small improvements in heat dissipation are
o
C (still air). These temperature rise
2
, and ideally should
www.diodes.com
IN
– V
10 of 14
SAT
150KHz, 5A PWM BUCK DC/DC CONVERTER
)
The AP1501A (TO-263 package) junction temperature rise above
ambient temperature with a 2A load for various input and output voltages.
This data was taken with the circuit operating as a buck switching
regulator with all components mounted on a PC board to simulate the
junction temperature under actual operating conditions. This curve can
be used for a quick check for the approximate junction temperature for
various conditions, but be aware that there are many factors that can
affect the junction temperature. When load currents higher than 3A are
used, double sided or multilayer PC boards with large copper areas
and/or airflow might be needed, especially for high ambient temperatures
and high output voltages.
For the best thermal performance, wide copper traces and generous
amounts of printed circuit board copper should be used in the board
layout. (Once exception to this is the output (switch) pin, which should not
have large areas of copper.) Large areas of copper provide the best
transfer of heat (lower thermal resistance) to the surrounding air, and
moving air lowers the thermal resistance even further.
Package thermal resistance and junction temperature rise numbers are
all approximate, and there are many factors that will affect these
numbers. Some of these factors include board size, shape, thickness,
position, location, and even board temperature. Other factors are, trace
width, total printed circuit copper area, copper thickness, single or
double-sided, multilayer board and the amount of solder on the board.
The effectiveness of the PC board to dissipate heat also depends on the
size, quantity and spacing of other components on the board, as well as
whether the surrounding air is still or moving.
Furthermore, some of these components such as the catch diode will
add heat to the PC board and the heat can vary as the input voltage
changes. For the inductor, depending on the physical size, type of core
material and the DC resistance, it could either act as a heat sink taking
heat away from the board, or it could add heat to the board.
AP1501A
SEPTEMBER 2009
©
Diodes Incorporated