AP1512 ANACHIP [Anachip Corp], AP1512 Datasheet - Page 8

• Manufacturer Part Number: AP1512
• Description: 50KHz, 2A/3A PWM Buck DC/DC Converter
• Manufacturer: ANACHIP [Anachip Corp]

50KHz, 2A/3A PWM Buck DC/DC Converter
+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
with a duty cycle of approximately V
minimize coupling to sensitive circuitry, the PC
board copper area connected to this pin should be
kept a minimum.
Feedback
Senses the regulated output voltage to complete
the feedback loop.
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 SD 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.
Anachip Corp.
www.anachip.com.tw
ON /OFF
IN
Typical Application Circuit (Continued)
B. Vin=10V~60V, Vout=3.3V, Iout=0.7A~2A, Iout below 0.7A DCM
Function Description
220uF/100V
Vin
C1
IN
– V
SAT
3.3u
C2
) and approximately – 0.5V,
ON/OFF
1
5
OUT
Vin
SD
/ V
AP1512/A
GND
IN
3
. To
OUTPUT
FB
8/12
2
4
Thermal Considerations
The AP1512/A is available in two packages, a 5-pin
TO-220 and a 5-pin surface mount TO-263.
The TO-220 package needs a heat sink under most
conditions. The size of the heatsink depends on the
input voltage, the output voltage, the load current
and the ambient temperature. The AP1512/A
junction
temperature for a 2A load and different input and
output voltages. The data for these curves was
taken with the AP1512/A (TO-220 package)
operating as a buck
switching regulator in an ambient temperature of
25
all approximate and there are many factors that can
affect
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 0.4 in
and ideally should 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
heat dissipation are realized. If further thermal
improvements are needed, double sided, multilayer
PC board with large copper areas and/or airflow are
recommended.
o
C (still air). These temperature rise numbers are
these
1
D1
SR360
temperature
33uH
L1
temperatures.
2
2
, only small improvements in
rises
C7
3.3u
AP1512/A
Higher
above
Rev.1.1 Oct. 14, 2005
1500uF/16V
C3
Vout
ambient
ambient
2
,