Active-Semi
ACT4082A
Rev0, 16-May-08
16V, 1.2A, 1.4MHz Step-Down DC/DC Converter in SOT23-6
FEATURES
• Wide 4.5V to 16V Input Voltage Range
• 1.2A Output Current (12VIN to 5VOUT)
• Output Adjustable Down to 0.81V
• 0.3Ω Internal Power MOSFET
• Up to 92% Efficiency
• Stable with Low ESR Ceramic Output Capacitors
• Fixed 1.4MHz Operating Frequency
• Internal Soft-Start Function
• Over Current Protection with Hiccup-Mode
• Thermal Shutdown
• Available in a SOT23-6 Package
APPLICATIONS
• TFT LCD Monitors
• Portable DVDs, Headphones, MP3 Players, etc.
• Car-Powered or Battery-Powered Equipment
• Set-Top Boxes
• Telecom Power Supplies
• DSL and Cable Modems and Routers
GENERAL DESCRIPTION
The ACT4082A is a current-mode step-down
DC/DC converter that supplies up to 1.2A into 5V
from a 12V input. 1.4MHz switching frequency al-
lows the use of tiny external components, and inter-
nal loop compensation provides simple, stable
power supplies with a minimum of external compo-
nents. Optimized for use with ceramic input and
output capacitors, the ACT4082A provides a very
compact 1.2A power supply for space constrained
mobile and consumer applications.
The ACT4082A operates over a wide input voltage
range and utilizes current-mode operation to pro-
vide excellent line and load transient response
while requiring no external compensation compo-
nents. Fault protection includes cycle-by-cycle cur-
rent limiting, frequency fold-back, hiccup mode, and
thermal shutdown. Internal soft-start provides a
controlled startup with no overshoot, even at light
loads.
The ACT4082A is available in a tiny SOT23-6 pack-
age and requires very few external components.
TYPICAL APPLICATION CIRCUIT
4.5V to 16V
VIN
IN
BST
Active-Semi
ON
OFF
ACT4082A SW
EN
VOUT
FB
G
Innovative PowerTM
-1-
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Copyright © 2008 Active-Semi, Inc.