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AX4103
PWM Control 3.5A Step-Down Converter
GENERAL DESCRIPTION AX4103 consists of step-down switching regulator with PWM control. These devise include a reference voltage source, oscillation circuit, error amplifier, internal PMOS and etc. AX4103 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to the duty ratio linearly form 0 up to 100%. An enable function, an over current protect function and short circuit protect function are built inside, and when OCP or SCP happens, the operation frequency will be reduced. 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 package, providing such outstanding features as low current consumption. FEATURES - Input voltage:4.5V to 23V - Output voltage:0.8V to VCC - Duty ratio:0% to 100% PWM control - Oscillation frequency:330KHz typ. Current Limit (CL), Enable function. Thermal Shutdown function. Short Circuit Protect (SCP). Built-in internal SW P-channel MOS. SOP-8L Pb-Free package.
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.1 Aug.06, 2010
AX4103
BLOCK DIAGRAM
SW
Oscillation Circuit
Reference Voltage
VCC
PWM - Switched Control Circuit Thermal Shutdown VEN + -
Current Limit
FB VSS
EN
NC
PIN ASSIGNMENT The package of AX4103 is SOP-8L; the pin assignment is given by: Name FB EN NC VCC SW VSS ORDER/MARKING INFORMATION Order Information Top Marking
Logo
Description Feedback pin Power-off pin H:normal operation(Step-down) L:Step-down operation stopped (All circuits deactivated) No Connect pin IC power supply pin Switch pin. Connect external inductor and diode here. GND pin
AX4103 X X X
Frequency Package Type Packing Blank : Tube Blank : 330Khz S: SOP-8L A : Taping
4 1 03 AX Y Y WW X
Part number ID code:internal WW: 01~52 Year: 10=2010 11=2011
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.1 Aug.06, 2010
AX4103
ABSOLUTE MAXIMUM RATINGS (at TA = 25°C)
Characteristics Symbol Rating Unit
Note : θJA is measured with the PCB copper area(need connect to SW pins) of approximately 1 in2(Multi-layer).
VCC Pin Voltage Feedback Pin Voltage ON/OFF Pin Voltage Switch Pin Voltage Power Dissipation Storage Temperature Range Operating Junction Temperature Range Operating Supply Voltage Output Current Thermal Resistance from Junction to case Thermal Resistance from Junction to ambient
VCC VFB VEN VSW PD TST TJ VOP IOUT θJC θJA
VSS - 0.3 to VSS + 25 VSS - 0.3 to VCC VSS - 0.3 to VCC + 0.3 VSS - 0.3 to VCC + 0.3 Internally limited -40 to +150 -20 to +125 4.5 to 23 0 to 3.5 25 70
V V V V mW °C °C V A °C/W °C/W
ESELECTRICAL CHARACTERISTICS (VIN = 12V, VOUT=3.3V, TA =25°C, unless otherwise specified) Characteristics Feedback Voltage Quiescent Current Feedback Bias Current Shutdown Supply Current Current Limit Line Regulation Load Regulation Oscillation Frequency Switching Rising Time Switching Falling Time EN Pin Logic input threshold voltage EN Pin Input Current Internal MOSFET RDSON Efficiency Symbol VFB ICCQ IFB ISD ICL △VOUT/VOUT VCC=8V~23V, IOUT=0.2A △VOUT/VOUT IOUT = 0.1 to 2A FOSC Tr Tf VENH VENL IENH IENL RDSON EFFI SW pin IOUT=2A IOUT=2A High (regulator ON) Low (regulator OFF) VEN=2.5V (ON) VEN=0.3V (OFF)
VCC=5V, VFB=0V VCC=12V, VFB=0V
Conditions
Min Typ Max Units
IOUT=0.1A 0.784 0.800 0.816 V VFB=1.2V force driver off 3 5 mA IOUT=0.1A 0.1 0.5 uA VEN =0V 4 2.0 -
2 1 0.2 15 15 20 -10
90 55
10 2 0.5 0.8 140 90
uA A % % ns ns V uA uA mΩ %
260 330 400 KHz
VCC = 12V, IOUT = 2A VOUT = 5V IOUT = 3A
-
91 90
-
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.1 Aug.06, 2010
AX4103
APPLICATION CIRCUIT
VIN+12V
R4 100K
AX4103
ON/OFF FB EN VSS VSS SW SW D1 B340 1 L1 22uH R1 6.8K C8 0.1uF C4 470uF 2
VOUT = 5V/3A
C2 470uF C6 0.1uF
NC VCC C3 0.1uF
R2 1.3K
VOUT = VFB x (1 +
R1 ) R2 VFB = 0.8V ; R2 suggest 0.8K ~ 6k
FUNCTION DESCRIPTIONS PWM Control The AX4103 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. In converters of the AX4103, the pulse width varies in a range from 0 to 100%, according to the load current. The ripple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current. Setting the Output Voltage Application circuit item shows the basic application circuit with adjustable output version. The external resistor sets the output voltage according to the following equation:
V
OUT
R1 0.8V 1 R2
Table 1 Resistor select for output .