Diodes AP1534 User Manual
Ap1534, Pwm control 2a step-down converter, Description
AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534
Document number: DS31314 Rev. 6 - 2
1 of 9
April 2011
© Diodes Incorporated
Description
AP1534 consists of step-down switching regulator with PWM
control. These devices include a reference voltage source,
oscillation circuit, error amplifier, internal PMOS.
AP1534 provides low-ripple 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 overshoot 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
built in to minimize 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 portable devices when
coupled with the SO-8 mini-packages, providing such
outstanding features as low current consumption. Since this
converter can accommodate an input voltage up to 18V, it is
also suitable for the operation via an AC adapter.
Pin Assignments
SO-8
(Top View)
1
2
3
4
5
6
7
8
AP1534
V
SS
V
CC
V
SS
Output
Output
OCSET
EN
FB
Features
•
Input voltage: 3.6V to 18V
•
Output voltage: 0.8V to V
CC
•
Duty ratio: 0% to 99% PWM control
•
Oscillation frequency: 300KHz typical
•
Current limit, Enable function
•
Thermal Shutdown function
•
Built-in internal SW P-channel MOS
•
SO-8: Available in “Green” Molding Compound
(No Br, Sb)
•
Lead Free Finish/RoHS Compliant (Note 1)
Applications
•
PC Motherboard
•
LCD Monitor
•
Graphic Card
•
DVD-Video Player
•
Telecom Equipment
•
ADSL Modem
•
Printer and other Peripheral Equipment
•
Microprocessor Core Supply
Notes:
1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
Typical Application Circuit
AP1534
+
-
V
SS
EN
C
C
R
A
R
B
B240A
FB
Vcc
Output
CVcc
V
OUT
=5V/2A
V
IN
R
OCSET
OCSET
C
OUT
C
IN
Optional
C
OCSET
C
EN
R
EN
Option
100K
L1
22uH
6.8K
1.3K
5.6K
0.1uF
+
-
C
0.1uF
470uF
470uF
0.1uF
(Note 2)
D1
Note: V
= V x (1+R /R )
R = 0.7K~5K
OUT
FB
A
B
B
Ω
Notes:
2. Suggested DIODES Power Schottky P/N: B240/B340 series.