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AX3112
PWM Control 3A Step-Down Converter
GENERAL DESCRIPTION AX3112 consists of step-down switching regulator with PWM control. The device includes a reference voltage source, oscillation circuit, error amplifier, internal PMOS and etc. AX3112 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to the duty ratio linearly forms 0 up to 100%. 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-EP package, providing such outstanding features as low current consumption. Since this converter can accommodate an input voltage up to 40V, it is also suitable for the operation via an AC adapter. FEATURES
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- Input voltage:8V to 40V - Adjustable version output voltage range from 3.3V to 38V - Duty ratio:0% to 100% PWM control - Oscillation frequency:100K/350 KHz Enable and auto restart function. Thermal Shutdown function / Internal OVP. Short Circuit Protect (SCP). Built-in internal SW P-channel MOS. SOP-8L-EP Pb-Free package.
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.3 May.23, 2011
Datasheet pdf - http://www.DataSheet4U.co.kr/
AX3112
BLOCK DIAGRAM
PIN ASSIGNMENT The package of AX3112 is SOP-8L-EP; the pin assignment is given by: Name Description EN/CT ON/OFF and auto restart control VSS GND pin Driver gate clamping pin. The pin VGATE must connect a 0.1uF capacitor to VCC VCC Operating voltage input Switch pin. Connect external inductor SW and diode here SENSE1 Current sense input1 SENSE2 Current sense input2 FB Feedback pin
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( Top View ) EN/CT VSS VGATE VCC 1 2 3 4 SOP–8L–EP SW AX3112 8 7 6 5 FB SENSE2 SENSE1 SW
ORDER/MARKING INFORMATION Order Information Top Marking
Logo
AX3112 X XX X
Frequency Package Type Packing Blank : 100KHz ES: SOP-8L-EP Blank : Tube A: 350KHz A : Taping
AX 3 1 1 2
A Y YWWX
Part number ID code: internal WW: 01~52 Year: 10=2010 11=2011
Blank: AX3112 A: AX3112A
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.3 May.23, 2011
Datasheet pdf - http://www.DataSheet4U.co.kr/
AX3112
ABSOLUTE MAXIMUM RATINGS (at TA = 25°C)
Characteristics Symbol Rating Unit
VCC Pin Voltage Feedback Pin Voltage EN/CT, OVP Pin Voltage SENSE1,SENSE2 Pin Voltage Switch Pin Voltage Power Dissipation Storage Temperature Range Operating Temperature Range Operating Supply Voltage Output Current Thermal Resistance from Junction to case Thermal Resistance from Junction to ambient
VCC VFB
VSS - 0.3 to VSS + 45 VSS - 0.3 to 38 VSS - 0.3 to 6 VSS - 0.3 to 38
V V V V V W °C °C V A °C/W °C/W
VSW PD TST TOP VOP IOUT θJC θJA
VSS - 0.3 to VCC + 0.3 (TJ – TA)/ θJA -40 to +165 -20 to +125 +8 to +40 0 to 3 15 40
Note : θJA is measured with the PCB copper are (need connect to Exposed pad) of approximately 1 in2(Multi-layer).
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.3 May.23, 2011
Datasheet pdf - http://www.DataSheet4U.co.kr/
AX3112
ELECTRICAL CHARACTERISTICS (VCC=12V, TA=25°C, unless otherwise specified) Characteristics FB Under Voltage Lockout UVLO Hysteresis OVP detect voltage Line Regulation Load Regulation Quiescent Current Oscillator frequency Max. Duty Cycle (ON) Min. Duty Cycle (OFF) Internal MOSFET RDSON Sense Voltage Sense Voltage Hysteresis EN/CT pin logic input threshold voltage EN/CT pin current EN/CT pin current Thermal shutdown Temp Thermal Shutdown Hysteresis Symbol VFB UVLO VOVP ICCQ FOSC DC RDSON VSENSE-h VEN VCT IEN/CT-C Shutdown mode Auto restart, VFB<0.4V Charge current
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Conditions IOUT=10mA Falling FB floating VCC=10 ~ 40V IOUT=0 ~ 1A, RSENSE = 140mΩ VFB > 1.2V AX3112 AX3112A Force driver on VFB = 0.7V Force driver off VFB = 1.2V VCC=12V, VFB = 0.7V
Min 80 280 110 0.5 -
Typ 6 0.8 1.250 0.5 0.3 3 100 350 100 0 110 125 45
Max Units V V V V % mA KHz % mΩ mV mV V uA uA °C °C 1 6 120 420 170 140 0.3 1.5
1.08 1.10 1.12
0.6% mV
VSENSE VSENSE1-VSENSE2
-32 1.5 160 40
-
IEN/CT-D Discharge current TSD TSH
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.3 May.23, 2011
Datasheet pdf - http://www.DataSheet4U.co.kr/
AX3112
APPLICATION CIRCUIT (1) AL CAPACITOR
C1 VCC=10~36V L1 D1 C3 470u C4 0.1u C5 0.1u 4 3 2 1 C9 0.1u U1 VCC VGATE VSS EN/CT SW SENSE1 SENSE2 FB 5 6 7 8 11K R4 B340A C7 470u C8 39K 0.1u Option R-sense 50mR R3 C2 10N VOUT=5.0V/2.05A
AX3112 / A
VOUT = 1.1V × (1 +
R3 ) R4 AX3112A 22u
L1 recommend value (VIN=10~36V ,VOUT=5V) Version L1 Value (H)
(2) MLCC
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AX3112 66u
R1 VCC=10~36V L1 D1 C3 22u C4 0.1u C5 0.1u 4 3 2 1 C9 0.1u U1 VCC VGATE VSS EN/CT SW SENSE1 SENSE2 FB 5 6 7 8 B340A 22uH
470R/Option
C1
10N VOUT=5.0V/2.