Document
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ACT4065A
Rev 0, 23-Apr-12
High Input 2A Step Down Converter FEATURES
• • • • • • • • •
2A Output Current Up to 95% Efficiency 6.0V to 30V Input Range 210kHz Switching Frequency Adjustable Output Voltage Cycle-by-Cycle Current Limit Protection Thermal Shutdown Protection Frequency Foldback at Short Circuit Stability with Wide Range of Capacitors, Including Low ESR Ceramic Capacitors
GENERAL DESCRIPTION
The ACT4065A is a current-mode step-down DC/DC converter that generates up to 2A output current at 210kHz switching frequency. The ACT4065A is highly efficient with peak efficiency at 95% when in operation. Protection features include cycle-by-cycle current limit, thermal shutdown, and frequency foldback at short circuit. The ACT4065A is available in SOP-8 package and requires very few external devices for operation.
• SOP-8 Package
Note: ACT4065A is the drop-in replacement for ACT4065 with feedback resistance value change.
APPLICATIONS
• TFT LCD Monitors • Portable DVDs • Car-Powered or Battery-Powered Equipments
• Set-Top Boxes • Telecom Power Supplies • DSL and Cable Modems and Routers • Termination Supplies
Efficiency vs. Load current
ACT4065A-001 95 VIN = 12V
90
Efficiency (%)
85 VIN = 24V 80
75 VOUT = 5V 70 10 100 1000 10000
Load Current (mA)
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ACT4065A
Rev 0, 23-Apr-12 TEMPERATURE RANGE
-40°C to 85°C
ORDERING INFORMATION
PART NUMBER
ACT4065ASH-T
PACKAGE
SOP-8
PINS
8
PACKING
TAPE & REEL
PIN CONFIGURATION
SOP-8
PIN DESCRIPTION
PIN NUMBER PIN NAME
1 2 3 4 5 6 7 8 BS IN SW G FB COMP EN N/C
PIN DESCRIPTION
Bootstrap. This pin acts as the positive rail for the high-side switch’s gate driver. Connect a 10nF between this pin and SW. Input Supply. Bypass this pin to G with a low ESR capacitor. See Input Capacitor in Application Information section. Switch Output. Connect this pin to the switching end of the inductor. Ground. Feedback Input. The voltage at this pin is regulated to 0.808V. Connect to the resistor divider between output and ground to set output voltage. Compensation Pin. See Compensation Techniques in Application Information section. Enable Input. When higher than 0.8V, this pin turns the IC on. When lower than 0.8V, this pin turn the IC off. Output voltage is discharged when the IC is off. This pin has a small internal pull-up current to a high level voltage when pin is not connected. Do not allow EN pin to exceed 6V. Not Connected.
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http://www.Datasheet-PDF.co
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ACT4065A
Rev 0, 23-Apr-12 PARAMETER VALUE
-0.3 to 30 -1 to VIN + 1 VSW - 0.3 to VSW + 7 -0.3 to 6 Internally limited 0.76 105 -40 to 150 -55 to 150 300
ABSOLUTE MAXIMUM RATINGSc
UNIT
V V V V A W °C/W °C °C °C IN Supply Voltage SW Voltage BS Voltage EN, FB, COMP Voltage Continuous SW Current Maximum Power Dissipation Junction to Ambient Thermal Resistance (θJA ) Operating Junction Temperature Storage Temperature Lead Temperature (Soldering, 10 sec)
c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = 12V, TJ = 25˚C, unless otherwise specified.)
PARAMETER
Input Voltage Feedback Voltage High-Side Switch On Resistance Low-Side Switch On Resistance SW Leakage High-Side Switch Current Limit COMP to Current Limit Transconductance Error Amplifier Transconductance Error Amplifier DC Gain Switching Frequency Short Circuit Switching Frequency Maximum Duty Cycle Minimum Duty Cycle Enable Threshold Voltage Enable Pull-Up Current Supply Current in Shutdown IC Supply Current in Operation Thermal Shutdown Temperature
SYMBOL
VIN VFB RONH RONL
TEST CONDITIONS
VOUT = 5V, ILOAD = 1A VCOMP = 1.5V
MIN
6 0.792
TYP
0.808 0.22 8
MAX
30 0.824
UNIT
V V Ω Ω
VEN = 0 ILIM GCOMP GEA AVEA fSW VFB = 0 DMAX VFB = 0.7V VFB = 1.0V Hysteresis = 0.1V Pin pulled up to 4.5V typically when left unconnected VEN = 0 VEN = 3V, VFB = 1.0V Hysteresis = 10°C 0.75 190 ΔICOMP = ±10µA Duty = 50%
1 3.5 3.4 650 4000 210 30 88
10
µA A A/V µA/V V/V
240
kHz kHz %
0 0.8 4 75 0.75 155 100 0.85
% V µA µA mA °C
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www.active-semi.com Copyright © 2012 Active-Semi, Inc.
Free Datasheet http://www.Datasheet-PDF.com/
®
ACT4065A
Rev 0, 23-Apr-12
FUNCTIONAL BLOCK DIAGRAM
FUNCTIONAL DESCRIPTION
As seen in, Functional Block Diagram, the ACT4065A is a current mode pulse width modulation (PWM) converter. The converter operates as follows: A switching cycle starts when the rising edge of the Oscillator clock output causes the High-Side Power Switch to turn on and the Low-Side Power Switch to turn off. With the SW side of the inductor now connected to IN, the inductor current ramps up to store energy in its magnetic field. The inductor current level is measured by the Current Sense Am.