AS1333
Data Sheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
The AS1333 is a simple, step-down DC-DC converter optimized for powering portable applications that require low
dropout voltages such as mobile phones, portable communicators, and similar battery powered RFIC devices. Besides
being packed with numerous features like current overload protection, thermal overload shutdown and soft start,
AS1333 displays the following characteristics:
!
!
Its operation is based on current-mode buck architecture with synchronous rectification for high efficiency.
Allows the application to operate at maximum efficiency over a wide range of power levels from a single Li-Ion bat-
tery cell.
Provides for a maximum load capability of 650mA in PWM mode, wherein the maximum load range may vary
depending on input voltage, output voltage and the selected inductor.
Is ranked at an efficiency of around 96% for a 400mA load with a 3.6V input and a fixed output voltage of 3.09V.
!
!
Figure 22. Functional Block Diagram
VDD
PV
IN
Oscillator
Current
Sense
PWM
COMP
Error
Amplifier
FB
NC
Soft Start
Mosfet
Control
Logic
SW
Main Control
Shutdown
Control
EN
AS1333
AGND
PGND
AS1333 is fabricated using a chip-scale 8-pin WL-CSP package, which requires special design considerations for
implementation. Its fine bumppitch requires careful board design and precision assembly equipment. This package
offers the smallest possible size, for space-critical applications such as cell phones, where board area is an important
design consideration. The size of the external components is reduced by using a high switching frequency (2MHz).
demonstrates that only three external power components are required for implementation. The WL-
CSP package is appropriate for opaque case applications, where its edges are not subject to highintensity ambient red
or infrared light. Also, the system controller should set EN low during power-up and other low supply voltage
conditions.
www.austriamicrosystems.com
Revision 1.02
9 - 16
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
