AP1501

150Khz, 3A PWM Buck DC/DC Converter

Anachip Corp.

www.anachip.com.tw

Rev.A7 Feb. 10, 2004

8/11

The

AP1501

(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 2A 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.

Marking Information

(1) TO263-5L

AC

1501-XX

Output Type:

1501: ADJ

1501-33: 3.3V

1501-50: 5.0V

1501-12: 12V

Logo

ID code

Year:

( Top view )

"02" = 2002

"01" = 2001

YY WW X X

Xth week: 01~52

Blank: normal

L: Lead Free Package

(2) TO220-5L

AC

1501-XX

Output Type:

1501: ADJ

1501-33: 3.3V

1501-50: 5.0V

1501-12: 12V

Logo

ID code

Year:

( Top view )

"02" = 2002

"01" = 2001

YY WW X X

Xth week: 01~52

Blank: normal

L: Lead Free Package