Diodes AP1520 - Manual

AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1520 Rev. 5 1 of 9 JULY 2009
DS31174 www.diodes.com © Diodes Incorporated
• Input Voltage: 3.6V to 23V
• Output Voltage: 0.8V to V
CC
• Duty Ratio: 0% to 100% PWM Control
• Oscillation Frequency: 300kHz typ.
• Current Limit, Enable Function
• Thermal Shutdown Function
• Built-in Internal SW P-Channel MOS
• SOP-8L Pb-Free Package
• SOP-8L: Available in “Green” Molding Compound
(No Br, Sb)
• Lead Free Finish/ RoHS Compliant (Note 1)
AP1520 consists of step-down switching regulator with PWM
control. These devices include a reference voltage source,
oscillation circuit, error amplifier and internal PMOS.
AP1520 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 100%. This converter also
contains an error amplifier circuit. An enable function, an over
current protection and a short circuit protection are built inside,
and when OCP or SCP happens, the operation frequency will be
reduced from 300kHz to 30kHz. Also, an internal compensation
block is built in to 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 portable devices when coupled with the
SOP- 8L package, providing such outstanding features as low
current consumption. Since this converter can accommodate an
input voltage up to 23V, it is also suitable for the operation via an
AC adapter.
• PC Motherboard
• LCD Monitor
• Graphic Card
• DVD-Video Player
• Telecom Equipment
• ADSL Modem
• Printer and other Peripheral Equipment
• Microprocessor Core Supply
• Networking Power Supply
Typical Application Circuit
AP1520
+
- V
SS
EN
C
C
R
A
R
B D1
FB
V cc Output
CVcc
V
OUT
V
IN
R
OCSET
OCSET C
OUT
C
IN
Optional
C
OCSET
C
EN
R
EN
Option
100K
Note: V
OUT
= V
FB
x (1+R
A
/R
B
)
R
B
=0.7K~5K ohm
L1
22uH
6.8K
1.3K
3K
0.1uF
+
-
C
0.1uF 470uF 680uF
0.1uF
Features General Description
Applications