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AX3604 Dual High-Efficiency PWM Step-Down DC-DC Converter
GENERAL DESCRIPTION The AX3604 is a dual high-efficiency Pulse-Width-Modulated (PWM) step-down DC-DC converter. It is capable of delivering 1A output current over a wide input voltage range from 2.5V to 5.5V, the AX3604 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and other handheld devices. Two operational modes are available: PWM/Low-Dropout auto-switch and shutdown modes. Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky diode is required in practical application. The AX3604 enters Low-Dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper PMOS. The AX3604 enter shutdown mode and consumes less than 0.1μA when EN pin is pulled low. The switching ripple is easily smoothed-out by small package filtering elements due to a fixed operation frequency of 1.5MHz. This along with small TDFN-12L (3x3) package provides small PCB area application. Other features include soft start, lower internal reference voltage with 2% accuracy, over temperature protection, and over current protection. FEATURES 2.5V to 5.5V Input Voltage Range Adjustable Output Voltage from 0.6V to VIN 1A Output Current/per channel High Efficiency : up to 95% No Schottky Diode Required 1.5MHz Fixed-Frequency PWM Operation Small 12-Lead TDFN Package
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.1 Mar.22, 2013
AX3604
BLOCK DIAGRAM
VIN1 OSC FB
0.6V SET
SLOPE COMP
Isense AMP
Soft-Star + RESET
Icomp
FB1
+
PWM LOGIC
NON-OVERLAP CONTROL
Over-Temperature and Short-Circuit Protection
Enable Logic
EN1 VIN2 OSC FB
0.6V SET
SLOPE COMP
Isense AMP
Soft-Star + RESET
Icomp
FB2
+
PWM LOGIC
NON-OVERLAP CONTROL
Over-Temperature and Short-Circuit Protection
Enable Logic
EN2
Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.1 Mar.22, 2013
-
Izero COMP
+
-
Izero COMP
+
+
+ LX1 GND1 LX2 GND2
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AX3604
PIN ASSIGNMENT The package of AX3604 is TDFN-12L (3×3); the pin assignment is given by: (Top View) Name Description 12 EN2 VIN2 1 VIN2 Power Input of Channel 2. 11 NC2 SW2 2 SW2 Pin for Switching of Channel 2. Ground. The exposed pad must be 10 FB2 GND2 3 GND soldered to a large PCB and 9 GND1 GND1,2 FB1 4 connected to GND for maximum 8 SW1 NC1 5 power dissipation. FB1 Feedback of Channel 1. 7 VIN1 EN1 6 NC1, 2 No Connection Pin. TDFN-12L (3 x 3) Chip Enable of Channel 1 (Active High). EN1 10 SW1 EN1 1 VEN1 ≦ VIN1. 9 GND1 FB1 2 VIN1 Power Input of Channel 1. Exposed 8 VIN1 VIN2 3 SW1 Pin for Switching of Channel 1. Pad (SGND) FB2 Feedback of Channel 2. 7 FB2 GND2 4 Chip Enable of Channel 2 (Active 6 EN2 SW2 5 EN2 High). TDFN-10L (3*3) VEN2 ≦ VIN2.
TOP View
ORDER/MARKING INFORMATION Order Information
Top Marking
3 6 04 Y Y W WX
Part number ID code: internal WW: 01~52 Year: 11=2011 12=2012 : : 19=2019
AX3604 XXX X
Packing Package Type J12: TDFN-12L (3*3) A : Taping J10: TDFN-10L (3*3)
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.1 Mar.22, 2013
AX3604
ABSOLUTE MAXIMUM RATINGS (at TA=25°C) Characteristics Supply Input Voltage EN1, FB1, LX1, EN2, FB2 and LX2 Pin Voltage Power Dissipation, PD @ TA = 25°C Lead Temperature (Soldering, 10 sec.) Storage Temperature Range Junction Temperature Thermal Resistance from Junction to case Thermal Resistance from Junction to ambient
Symbol VIN1/ VIN2 PD TST TJ θJC θJA
Rating Unit -0.3 to 6 V -0.3 to VIN + 0.3 V 1.667 W 260 °C -65 to 150 °C 150 °C 8.2 °C/W 60 °C/W
Note: θJA is measured with the PCB copper area of approximately 1 in2(Multi-layer). That need connect to exposed pad.
RECOMMENDED OPERATING CONDITIONS Characteristics Supply Input Voltage Junction Temperature Range Ambient Temperature Range
Symbol VIN TJ TA
Rating 2.5 to 5.5 -40 to 125 -40 to 85
Unit V °C °C
Note: The device is not guaranteed to function outside its operating conditions.
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.1 Mar.22, 2013
AX3604
ELECTRICAL CHARACTERISTICS (VIN = 3.6V, VOUT = 2.5V, VREF = 0.6V, L = 2.2uH, CIN = 4.7μF, COUT = 10μF, TA = 25°C, IMAX= 1A unless otherwise specified) Characteristics Symbol Conditions Min Typ Max Units Channel 1 and Channel 2 Input Voltage Range VIN 2.5 5.5 V Under Voltage Lock Out UVLO 2 V threshold Quiescent Current IQ IOUT=0mA, VFB = VREF + 5% - 250 350 μA ISHDN EN=GND Shutdown Current - 0.1 1 μA Reference Voltage VREF For Adjustable Output Voltage 0.588 0.6 0.612 V Adjustable Output Voltage VIN VOUT (Note 1) VREF V Range −ΔV V = 2.5V to 5.5V, ΔVOUT IN -3 +3 % VOUT = 1.2V, 0A < IOUT < 1A V = 2.5V to 5.5V, ΔVOUT IN -3 3 % VOUT = 1.3V, 0A < IOUT < 1A V = 2.5V to 5.5V, ΔVOUT IN -3 3 % Outp.