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Active-Semi |
Active-Semi
ACT4050
Rev 2, 01-Jul-11
Wide Input 3.5A Step Down Converter
FEATURES
• 3.5A Output Current
• Up to 96% Efficiency
• 4.5V to 15V Input Range
• 12µA Shutdown Supply Current
• 400kHz Switching Frequency
• Adjustable Output Voltage From 0.817V
• Cycle-by-Cycle Current Limit Protection
• Thermal Shutdown Protection
• Frequency Fold-Back at Short Circuit
• Stability with Wide Range of Capacitors,
Including Low ESR Ceramic Capacitors
• SOP-8/EP (Exposed Pad) Package
APPLICATIONS
• Digital TV
• Portable DVDs
• Car-Powered or Battery-Powered Equipments
• Set-Top Boxes
• Telecom Power Supplies
• Consumer Electronics
GENERAL DESCRIPTION
The ACT4050 is a current-mode step-down DC/DC
converter that provides up to 3.5A of output current
at 400kHz switching frequency. The device utilizes
Active-Semi’s proprietary high voltage process for
operation with input voltages up to 15V.
The ACT4050 provides fast transient response and
eases loop stabilization while providing excellent
line and load regulation. This device features a very
low ON-resistance power MOSFET which provides
peak operating efficiency up to 96%. In shutdown
mode, the ACT4050 consumes only 12μA of supply
current.
This device also integrates protection features
including cycle-by-cycle current limit, thermal
shutdown and frequency fold-back at short circuit.
The ACT4050 is available in a SOP-8/EP (Exposed
Pad) package and requires very few external
devices for operation.
TYPICAL APPLICATION CIRCUIT
Efficiency vs. Load Current
100
VIN = 7V
90
VIN = 12V
80
70
60
50 VOUT = 5V
0 500 1000 1500 2000 2500 3000 3500
Load Current (mA)
Innovative PowerTM
- 1 - www.active-semi.com
Copyright © 2011 Active-Semi, Inc.
Active-Semi
ORDERING INFORMATION
PART NUMBER
ACT4050YH
ACT4050YH-T
TEMPERATURE RANGE
-40°C to 85°C
-40°C to 85°C
PIN CONFIGURATION
ACT4050
Rev 2, 01-Jul-11
PACKAGE
SOP-8/EP
SOP-8/EP
PINS
8
8
PACKING
TUBE
TAPE & REEL
SOP-8/EP
PIN DESCRIPTIONS
PIN NAME
DESCRIPTION
1
BS
Bootstrap. This pin acts as the positive rail for the high-side switch’s gate driver. Connect
a 10nF capacitor between BS and SW.
2
IN
Input Supply. Bypass this pin to GND with a low ESR capacitor. See Input Capacitor in
the Application Information section.
3 SW Switch Output. Connect this pin to the switching end of the inductor.
4
GND
Ground.
5
FB
Feedback Input. The voltage at this pin is regulated to 0.817V. Connect to the resistor
divider between output and ground to set output voltage.
6 COMP Compensation Pin. See Stability Compensation in the Application Information section.
Enable Input. When higher than 1.3V, this pin turns the IC on. When lower than 0.9V, this
7 EN pin turns the IC off. Output voltage is discharged when the IC is off. When left
unconnected, EN is pulled up to 4.5V typical with a 2µA pull-up current.
8 N/C Not Connected.
Exposed Pad shown as dashed box. The exposed thermal pad should be connected to
EP
EP
board ground plane and pin 4. The ground plane should include a large exposed copper
pad under the package for thermal dissipation (see package outline). The leads and
exposed pad should be flush with the board, without offset from the board surface.
Innovative PowerTM
- 2 - www.active-semi.com
Copyright © 2011 Active-Semi, Inc.
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