18V 4A 300KHz BUCK CONVERTER
Description
AP1539 consists of step-
down switching regulator with PWM control.
These devices include a reference voltage source, oscillation circuit,
error amplifier, internal PMOS.
AP1539 provides low-rippl
e power, high efficiency, and excellent
transient characteristics. The PWM control circuit is able to vary the
duty ratio linearly from 0 up to 99
%. This converter also contains an
error amplifier circuit as well as a soft-
start circuit that prevents
overs
hoot at startup. An enable function, an over current protect
function and a short circuit protect function are built inside, and when
OCP or SCP happens, the operation frequency will be reduced from
300KHz to 50KHz. Also, an internal compensation block is
minimum external component count. With the addition of an internal P-
channel Power MOS, a coil, capacitors, and a diode connected
externally, these ICs can function as step-
down switching regulators.
They serve as ideal power supply units for p
coupled with the SOP-8L-DEP mini-
package, providing such
outstanding features as low current consumption. Since this converter
can accommodate an input voltage up to 18
V, it is also suitable for the
operation via an AC adapter.
Features
• Input voltage: 3.6V to 18V
• Output voltage: 0.8V to VCC
• Output current: up to 4A
• Duty ratio: 0% to 99% PWM control
• Oscillation frequency: 300KHz typ.
• Soft-start like, Current limit and Enable function
• Thermal Shutdown function
• Built-in internal SW P-channel MOS
• SOP-8L-DEP: Available in “Green” Molding Compound (No Br, Sb)
• Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
• Halogen and Antimony Free. “Green” Device (Note 3)
•
For automotive applications requiring specific change control
(i.e. parts qualified to AEC-
Q100/101/200, PPAP capable, and
manufactured in IATF 16949 certified facilities), please
us or your local Diodes representative.
https://www.diodes.com/quality/product-definitions/
Pin Assignments
1
2
3
4
8
7
6
5
FB
Output
OCSET
Output
EN
Vss
Vss
VCC
1
2
( Top View )
(Note 4 )
SOP-8L-DEP (Dual Exposed Pads)
Note: 4. Exposed pad 1 is connected to VSS and exposed pad 2 is connected to
Output. The board layout for exposed pads needs to be considered to
avoid short circuit.
Applications
• PC Motherboard
• LCD Monitor
• Graphic Card
• DVD-Video Player
• Telecom Equipment
• ADSL Modem
• Printer and other Peripheral Equipment
• Microprocessor core supply
Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant.
2. See https://www.diodes.com/quality/lead-free/ for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and
Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
NOT RECOMMENDED FOR NEW DESIGN
CONTACT US
AP1539
Document number: DS31477 Rev. 6 - 3
1 of 12
www.diodes.com
February 2020
© Diodes Incorporated