AX2002/A 2A, 0.25V Feedback Voltage Step-Down Switching Regulators for LED Driver GENERAL DESCRIPTION AX2002/A consists of step-down switching regulator with PWM control. These devise include a reference voltage source, oscillation circuit, error amplifier, internal PMOS and etc. AX2002/A provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to the duty ratio linearly from 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. Since this converter can accommodate an input voltage up to 23V, it is also suitable for the operation via an AC adapter. FEATURES - Input voltage：3.6V to 23V - Output voltage：0.25V to Vcc - LED Backlight and High Power LED Application Duty ratio：0% to 100% PWM control Oscillation frequency： AX2002 : 330KHz typ. AX2002A : 500KHz typ. - Enable/Disable function. Current Limit (CL), Thermal Shutdown and Short Circuit Protections (SCP). Built-in internal SW P-channel MOS. No output capacitor is stable. SOP-8L Pb-Free package. 1/8 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.4 Feb.12, 2009 深圳明和科技有限公司 www.led-ics.com Tel:0755-82536500 LED Driver (2A, 0.25V FB Voltage) AX2002/A Block Diagram SW Oscillator Circuit Vcc Reference Voltage + PWM Switched Control Circuit Thermal Shutdown - FB Vss Current Limit VEN Comp EN PIN ASSIGNMET The package of AX2002/A is SOP-8L; the pin assignment is given by: Name Description FB Feedback pin Power-off pin H：normal operation(Step-down) L：Step-down operation stopped (All circuits deactivated) Compensation pin ( Top View ) FB 1 8 Vss EN 2 7 Vss Comp 3 6 SW Vcc 4 5 SW AX2002/A EN Comp SOP-8L VCC SW VSS IC power supply pin Switch pin. Connect inductor/diode here. GND pin external ORDER/MARKING INFORMATION Order Information AX2002 X X X Top Marking Logo Package Type Packing Frequecny Blank : 330KHz S: SOP-8L Blank : Tube A : 500KHz A : Taping AX 2002 AXXXXX Part number ID code: internal WW: 01~52 AX2002A Year : 08 = 2008 2/8 Axelite Confidential Materials, do not copy or distribute without written consent. 深圳明和科技有限公司 www.led-ics.com Rev.1.4 Feb.12, 2009 Tel:0755-82536500 LED Driver (2A, 0.25V FB Voltage) AX2002/A Absolute Maximum Ratings (at Ta=25℃) Characteristics Symbol Rating Unit VCC Pin Voltage VCC VSS - 0.3 to VSS + 25 V Feedback Pin Voltage VFB VSS - 0.3 to VCC V ON/OFF Pin Voltage VEN VSS - 0.3 to VCC + 0.3 V Switch Pin Voltage VSW VSS - 0.3 to VCC + 0.3 V Power Dissipation PD Internally limited mW Storage Temperature Range TST -40 to +150 ℃ Operating Temperature Range TOP -40 to +125 ℃ Operating Supply Voltage VOP +3.6 to +23 V Thermal Resistance from Junction to case θJC 25 ℃/W Thermal Resistance from Junction to ambient θJA 70 ℃/W Note : θJA is measured with the PCB copper area(need connect to SW pins) of approximately 1 Electrical Characteristics (VIN = 12V, Ta=25°C, unless otherwise specified) Characteristics Symbol Conditions Min Typ Feedback Voltage VFB IOUT=0.2A 0.24 Quiescent Current ICCQ VFB=1.2V force driver off Feedback Bias Current IFB IOUT=0.1A Shutdown Supply Current ISD VEN =0V Switch Current ISW in2(Multi-layer). Max Units 0.25 0.26 V 3 5 mA - 0.1 0.5 uA - 2 10 uA 2.5 - - A Line Regulation △VOUT/VOUT VCC = 5V~23V, IOUT=0.2A - 1 2 % Load Regulation △VOUT/VOUT IOUT = 0.1 to 2A - 0.2 0.5 % AX2002 260 330 400 KHz AX2002A 400 500 600 KHz VSH High (regulator ON) 2.0 - - VSL Low (regulator OFF) - - 0.8 ISH VEN=2.5V (ON) - 20 - uA ISL VEN=0.3V (OFF) - -10 - uA VCC=5V, VFB=0V - 100 140 VCC=12V, VFB=0V - 70 100 IOUT = 1A - 91 - IOUT = 2A - 91 - - 140 - FOSC Oscillation Frequency EN Pin Logic input threshold voltage EN Pin Input Current Internal MOSFET RDSON RDSON Efficiency EFFI Thermal shutdown Temp TSD VOUT = 5V V mΩ % ℃ 3/8 Axelite Confidential Materials, do not copy or distribute without written consent. 深圳明和科技有限公司 www.led-ics.com Rev.1.4 Feb.12, 2009 Tel:0755-82536500 LED Driver (2A, 0.25V FB Voltage) AX2002/A Application Circuit A. 1W/3W LED*1 for DC Input U1 VCC 1 R1 100K 2 3 4 FB VSS 8 7 VSS 6 SW 5 SW EN COMP VCC VOUT L1 22uH (10uH for AX2002A) D7 LED AX2002/A 1N4148 R4 4.7K Option D6 C2 22u C3 0.1u C4 R5 100K 1u D5 C1 B240A 4.7u R2 0.75R/0.33R 1W/3W B. 1W/3W LED*1 for AC Input (1) No Output Capacitor U1 1 2 AC 12V IN FB EN 3 COMP 4 VCC AC D4 AC D3 AC D2 VSS 8 7 VSS SW 6 SW 5 VOUT L1 D2 LED AX2002/A R5 AC D1 C3 C2 Part No. AX2002 AX2002A 0.1u ILED R2 D5 C5 100nF B240A R2 C2 R5 350mA 0.715Ω 87.5mW 100uF 0.22K 750mA 0.333Ω 189mW 220uF 0.47K 1000mA 0.250Ω 250mW 330uF 0.47K 350mA 0.715Ω 87.5mW 100uF 0.22K 750mA 0.333Ω 189mW 220uF 0.47K 1000mA 0.250Ω 250mW 330uF 0.47K L1 68uH 47uH 4/8 Axelite Confidential Materials, do not copy or distribute without written consent. 深圳明和科技有限公司 www.led-ics.com Rev.1.4 Feb.12, 2009 Tel:0755-82536500 LED Driver (2A, 0.25V FB Voltage) AX2002/A (2) Add 4.7uF Output Capacitor U1 1 2 AC 12V IN AC D4 AC D3 AC D2 AC D1 C4 C3 C2 Part No. AX2002 AX2002A FB EN 3 COMP 4 VCC R5 100R VSS 8 7 VSS SW 6 SW 5 ILED VOUT D2 LED AX2002/A C1 4.7u R2 R2 D5 C5 100n 0.1u L1 B240A C2 350mA 0.715Ω 87.5mW 100uF 750mA 0.333Ω 189mW 220uF 1000mA 0.250Ω 250mW 330uF 350mA 0.715Ω 87.5mW 100uF 750mA 0.333Ω 189mW 220uF 1000mA 0.250Ω 250mW 330uF C4 L1 10nF 33uH 3.3nF 22uH Function Descriptions PWM Control The AX2002/A consists of DC/DC converters that employ a pulse-width modulation (PWM) system. In converters of the AX2002/A, 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 ILED Current Application circuit item shows the basic application circuit with AX2002/A adjustable output version. The external resistor sets the LED output current according to the following equation: 5/8 Axelite Confidential Materials, do not copy or distribute without written consent. 深圳明和科技有限公司 www.led-ics.com Rev.1.4 Feb.12, 2009 Tel:0755-82536500 LED Driver (2A, 0.25V FB Voltage) I LED AX2002/A ⎛ 0.25V ⎞ =⎜ ⎟ ⎝ R2 ⎠ Table 1 Resistor select for LED output current setting ILED R2 350mA 0.715Ω 87.5mW 750mA 0.333Ω 189mW 1000mA 0.250Ω 250mW RDS(ON) Current Limiting The current limit threshold is setting by the internal circuit. Compensation Please refer the table of application circuit. For DC input, the option circuit for compensation is connecting R4 and a 4148 diode to Vout. In order to protect short circuit and thermal shutdown release for LED. PCB layout guide If you need low Tc & Tj or large PD (Power Dissipation), the dual SW pins (5&6) on the SOP-8L package are internally connected to die pad, The PCB layout should allow for maximum possible copper area at the SW pins of the AX2002/A. 6/8 Axelite Confidential Materials, do not copy or distribute without written consent. 深圳明和科技有限公司 www.led-ics.com Rev.1.4 Feb.12, 2009 Tel:0755-82536500 AX2002/A LED Driver (2A, 0.25V FB Voltage) Typical Characteristics Temperature vs. Iccq (Vcc=12V) 10 Shutdown Current (uA) 4 3.6 Iccq (mA) Temperature vs. Shutdown Current (Vcc=12V) 3.2 2.8 2.4 8 6 4 2 0 2 -40 -40 -25 0 25 50 85 105 -25 125 Temperature (℃) Temperature vs. VFB (Vcc=12V Iout300mA Rcomp=100K) 25 50 85 105 125 Temperature vs. Frequency (Vcc=12V Vout=3.3V) 0.26 600 500 Frequency (KHz) 0.256 VFB (V) 0 Temperature (℃ ) 0.252 0.248 AX2002A 400 300 200 0.244 100 0.24 0 -40 -25 0 25 50 85 105 AX2002 -40 125 -25 Temperature (℃ ) Line Regulation (Vout=3.3V) 0.257 0 25 50 85 105 125 Temperature (℃ ) Iout vs. EFFI (Vcc=12V) 100 0.255 EFFI (%) VFB (V) 95 Vout=5V 0.253 0.251 0.249 90 85 Vout=3.3V 80 0.247 75 0.245 70 3.6V 4V 5V 12V 15V 20V 22V 23V 0.5 1 1.5 2 Iout (A) Vcc 7/8 Axelite Confidential Materials, do not copy or distribute without written consent. 深圳明和科技有限公司 www.led-ics.com Rev.1.4 Feb.12, 2009 Tel:0755-82536500 LED Driver (2A, 0.25V FB Voltage) AX2002/A H E Package Outlines L DETAIL A b D e Symbol A A1 A2 C D E H L b e y θ y A1 C A A2 7 (4X) DETAIL A Dimensions In Millimeters Min. Nom. Max. 1.40 1.60 1.75 0.10 0.25 1.30 1.45 1.50 0.19 0.20 0.25 4.80 4.90 5.00 Dimensions In Inches Min. Nom. Max. 0.055 0.063 0.069 0.040 0.100 0.051 0.057 0.059 0.0075 0.008 0.010 0.189 0.193 0.197 3.80 5.79 0.38 0.33 4.00 6.20 1.27 0.51 0.150 0.228 0.015 0.013 0.10 8O 0O 0O 3.90 5.99 0.71 0.41 1.27 TYP - 0.154 0.236 0.028 0.016 0.050 TYP - 0.157 0.244 0.050 0.020 0.004 8O 8/8 Axelite Confidential Materials, do not copy or distribute without written consent. 深圳明和科技有限公司 www.led-ics.com Rev.1.4 Feb.12, 2009 Tel:0755-82536500