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| AP1533_09 Datasheet, PDF (1/9 Pages) Diodes Incorporated – PWM CONTROL 1.8A STEP-DOWN CONVERTER | |||
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AP1533
PWM CONTROL 1.8A STEP-DOWN CONVERTER
Features
General Description
⢠Input voltage: 4V to 23V
⢠Output voltage: 0.8V to VCC
⢠Output current: 1.8A up to peak 2A
⢠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: Available in âGreenâ 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
Typical Application Circuit
AP1533 consists of step-down switching regulator with PWM
control. These devices include a reference voltage source,
oscillation circuit, error amplifier, internal PMOS.
AP1533 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 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 mini-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.
VIN
Vcc
Output
ROCSET COCSET
3.3K Option
AP1533
C IN
OCSET
FB
470uF
EN
CVcc
R EN
100K
VSS
0.1uF
C EN
0.1uF
L1
33uH
CC
Optional
D1*
VOUT=5V/1.8A
RA
6.8K
+C +
- 0.1uF-
RB
1.3K
COUT
470uF
VOUT= V FB x (1+ RA/RB)
RB= 0.7K~5K ohm
* Suggested DIODES Power Schottky P/N: B340 series or PDS340.
AP1533 Rev. 4
DS31192
1 of 9
www.diodes.com
JULY 2009
© Diodes Incorporated
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