AX3001 150KHz, 2A PWM Buck DC/DC Converter GENERAL DESCRIPTION The AX3001 series are monolithic IC designed for a step-down DC/DC converter, and own the ability of driving a 2A load without additional transistor. It saves board space. The external shutdown function can be controlled by logic level and then come into standby mode. The internal compensation makes feedback control having good line and load regulation without external design. Regarding protected function, thermal shutdown is to prevent over temperature operating from damage, and current limit is against over current operating of the output switch. If current limit function occurs and VFB is down below 0.5V, the switching frequency will be reduced. The AX3001 series operates at a switching frequency of 150KHz thus allow smaller sized filter components than what would be needed with lower frequency switching regulators. The output version included fixed 3.3V, 5V, 12V, and an adjustable type. The chips are available in a standard 8-lead SOP package. FEATURES - Output voltage: 3.3V, 5V, 12V and adjustable output version. - Adjustable version output voltage range, 1.23V to 19.5V. - 150KHz fixed switching frequency. - Voltage mode non-synchronous PWM control. - Thermal-shutdown and current-limit protection. - ON/OFF shutdown control input. - Short Circuit Protect (SCP). - Operating voltage can be up to 22V. - Output load current: 2A. - SOP-8L Pb-Free packages. - Low power standby mode. - Built-in switching transistor on chip. 1/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 BLOCK DIAGRAM EN 200mV V CC 220mV CURRENT SOURCE BIAS 1.235V REFERENCE 2.5V REGULATOR START UP + _ COMP. Current limit 150kHz OSC. _ FB COMP. + R2 + AMP _ + COMP. _ COMP. CONTROL + DRIVER SWITCH R1 SW Thermal Shutdown Vss ADJ : R2=0Ω, R1=OPEN PIN ASSIGNMENT The package of AX3001 is SOP-8L; the pin assignment is given by: Name (Top View) Vcc SW FB EN 1 2 3 4 8 7 6 5 SOP-8L Vss Vss Vss Vss Description VCC Operating voltage input SW Switching output FB Output voltage feedback control EN ON/OFF Shutdown VSS GND pin 2/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 ORDER INFORMATION Order Information AX3001- XX X X Output Voltage Package Type Packing Blank : Tube S: SOP-8L 33:3.3V A : Taping 50:5.0V 12: 12V Blank:ADJ MARKING INFORMATION Top Marking ADJ Logo AX3001 XXXXX Part number ID code: internal WW: 01~52 Year : 06 = 2006 FIX Logo -50 AX 3001 XXXXX Part number Output Voltage ID code: internal WW: 01~52 Year : 06 = 2006 3/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 Absolute Maximum Ratings Characteristics Symbol Rating Unit Maximum Supply Voltage VCC +24 V ON/OFF Pin Input Voltage VEN -0.3 to VCC V Feedback Pin Voltage VFB -0.3 to 16 V Output Voltage to Ground VOUT -0.8 V Power Dissipation Internally limited PD ( TJ-TA ) / θJA W Storage Temperature Range TST -65 to +150 ℃ Operating Temperature Range TOP -20 to +125 ℃ Operating Supply Voltage VOP +4.5 to +22 V Thermal Resistance from Junction to case θJC 20 ℃/W Thermal Resistance from Junction to ambient θJA 60 ℃/W Note : θJA is measured with the PCB copper area(need connect to VSS pins) of approximately 1.5 in2 (Multi-layer). Electrical Characteristics (Unless otherwise specified, Ta=25°C, VCC=12V for 3.3V, 5V, adjustable version and VCC=18V for the 12V version. ILOAD = 0.2A) Characteristics Symbol Quiescent Current IQ Feedback bias current IFB Shutdown supply Current ISD Oscillator frequency FOSC Oscillator frequency of short circuit protect FSCP Max. Duty Cycle (ON) DC Min. Duty Cycle (OFF) Current limit ICL Saturation voltage SW pin=0V SW pin=-0.8V VSA T SW pin leakage current ISW L Conditions VFB=12V force driver off VFB=1.3V (Adjustable version only) EN pin=5V VCC=22V 127 (Adjustable) When VFB<0.5V (Fixed)When < VOUT*40% VFB=0V force driver on VFB=12V force driver off Pear current, No outside circuit V FB=0V force driver on IOUT=2A, No outside circuit VFB=0V force driver on No outside circuit VFB=12V force driver off VCC=22V force driver off EN pin logic input current VIL VIH IH Low (regulator ON) High (regulator OFF) VEN=2.5V (OFF) EN pin input current IL VEN=0.5V (ON) EN pin logic input threshold voltage Thermal shutdown Temp Min Typ Max Units 4 8 mA -10 -50 nA 35 100 uA 150 50 50 100 173 KHz KHz KHz % 0 2.4 A 1.2 1.4 V -200 uA -5 2.0 TSD 1.3 -0.1 mA 0.6 -0.5 -0.01 135 V uA ℃ 4/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 Electrical Characteristics (Continued) version Characteristics Symbol Conditions Min Typ Max Units 1.193 1.23 1.267 ILOAD =0.2A Output Feedback V FB AX3001-ADJ VOUT programmed voltage V for 3.3V Efficiency η Output voltage V OUT Efficiency η Output voltage V OUT Efficiency η Output voltage V OUT Efficiency η VCC = 12V, ILOAD=2A 79 % V ILOAD =0.2A 3.20 3.30 3.40 AX3001-3.3V 80 VCC = 12V, ILOAD=2A ILOAD =0.2A 4.85 AX3001-5.0V VCC = 12V, ILOAD=2A 5.00 % V 5.15 84 % ILOAD =0.2A V 11.64 12.0 12.36 AX3001-12V VCC = 15V, ILOAD = 2A % 90 5/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 Application Circuit (1) Adjustable Output Voltage Version VIN=12V Vcc Vss SW Vss FB Vss 2 C1 470uF C2 0.1uF 3 4 2 33uH U1 1 Vout=5.0V/2A L1 1 EN Vss R1 4.7K 8 7 D1 B340A 6 C3 470uF 5 C6 0.1uF R2 1.5K AX3001 ON/OFF Vout = VFB × (1 + R1 R2 ) VFB = 1.23V R2 = 0.47K ~ 2.6K Table 1 Resistor select for output voltage setting VOUT R2 R1 1.5K 4.7K 1.8K 5.6K 1.5K 2.5K 1.8K 3.0K 2.5V 1.8K 1.8K 1.8V 1.8K 0.82K 5V 3.3V (2) Fixed Output Voltage Version VIN=12V 2 C2 0.1uF 3 4 Vcc Vss SW Vss FB Vss EN 2 33uH U1 1 C1 470uF Vout=3.3V/2A L1 1 Vss 8 7 6 D1 B240A 5 C3 470uF C6 0.1uF AX3001-33 6/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 Application Circuit (Continued) (3) Adjustable Output Voltage Version With Delayed Startup VIN=12V 1 1 C1 470uF C2 0.1uF Vss SW Vss FB Vss EN Vss 3 4 R3 100k Vcc 2 C4 0.1uF ON/OFF L1 Vout=2.5V/2A 2 22uH U1 R1 1.3K 8 7 D1 B240A 6 5 C3 470uF C6 0.1uF R2 1.2K AX3001 Vout = VFB × (1 + R1 ) R2 VFB = 1.23V R2 = 0.47K ~ 2.6K (4) Inverting -5V Regulator with Delayed Startup VIN=5~20V 33uH 2A/30V 0.1uF 220uF 220uF 0.1uF 1 Vcc 2 SW 3 FB 4 EN 100k Vss 8 Vss 7 Vss Vss 6 100uF 0.1uF IN5400 3A/20V 5 VOUT -5V200mA AX3001-50 7/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 Function Descriptions Pin Functions Vcc This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be presented at this pin to minimize voltage transients and to supply the switching currents needed by the regulator. Vss Circuit ground. SW Internal switch. The voltage at this pin switches between (+VCC – VSAT) and approximately – 0.5V, with a duty cycle of approximately VOUT / VCC. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin should be minimized. Feedback Senses the regulated output voltage to complete the feedback loop. EN Allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total input supply current to approximately 100uA. Pulling this pin below a threshold voltage of approximately 1.3V turns the regulator on, and pulling this pin above 1.3V (up to a maximum of Vcc) shuts the regulator down. If this shutdown feature is not needed, the EN pin can be wired to the ground pin. Thermal Considerations The SOP-8 package needs a heat sink under most conditions. The size of the heat sink depends on the input voltage, the output voltage, the load current and the ambient temperature. The AX3001 junction temperature rises above ambient temperature for a 2A load and different input and output voltages. The data for these curves was taken with the AX3001 (SOP-8 package) operating as a buck-switching regulator in an ambient temperature of 25℃ (still air). These temperature increments are all approximate and are affected by many factors. Higher ambient temperatures requires more heat sinker. 8/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 Function Descriptions (Continued) For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper (need connect to the VSS pins) should be used in the board layout, (One exception is the SW(switch) pin, which should not have large areas of copper.) Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air, and moving air lowers the thermal resistance even further. Package thermal resistance and junction temperature increments are all approximate. The increments are affected by a lot of factors. Some of these factors include board size, shape, thickness, position, location, and even board temperature. Other factors are, trace width, total printed circuit copper area, copper thickness, single or double-sided, multi-layer board and the amount of solder on the board. The effectiveness of the PC board to dissipate heat also depends on the size, quantity and spacing of other components on the board, as well as whether the surrounding air is still or moving. Furthermore, some of these components such as the catch diode will add heat to the PC board and the heat can vary as the input voltage changes. For the inductor, depending on the physical size, type of core material and the DC resistance, it could either act as a heat sink taking heat away from the board, or it could add heat to the board. 9/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 Typical Characteristics VOUT VS VIN ICCQ VS VIN Iccq VS VIN 6.00 3.40 5.00 3.35 4.00 Iccq(mA) Vout(V) VOUT VS VIN 3.45 3.30 3.00 3.25 2.00 3.20 1.00 0.00 3.15 4 6 4 8 10 12 14 16 18 20 22 24 Vin(V) FOSC VS VIN 6 8 10 12 14 16 18 20 22 24 Vin(V) FOSC VS TEMPERATURE FOSC VS TEMP 180 165 170 160 160 FOSC (KHz) Fosc(KHz) Fosc VS VIN 170 155 150 150 140 145 130 140 120 4 6 8 -20 10 12 14 16 18 20 22 24 Vin(V) 0 20 60 80 100 120 temp (℃ ) VFB VS TEMPERATURE ICCQ VS TEMPERATURE ICCQ VS TEMP VFB VS TEMP 6.0 1.28 5.0 ICCQ (mA) 1.26 VFB (V) 40 1.24 1.22 1.20 4.0 3.0 2.0 1.0 0.0 1.18 -20 0 20 40 60 80 100 120 -20 0 20 temp (℃ ) 40 60 80 100 120 temp (℃ ) 10/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 150KHz, 2A PWM Buck DC/DC Converter AX3001 Typical Characteristics Output Ripple Power on test wave (VIN=12V, VOUT=3.3V, IOUT=2A) (VIN=12V, VOUT=5V, IOUT=2A ) VOUT SW VIN SW VOUT (AC) ISW ISW Load Transient Response EN on test wave (VIN=12V, VOUT=5V, IOUT=0.1~2A) (VIN=12V, VOUT=5V, IOUT=2A ) VOUT SW VIN SW VOUT (AC) ISW ISW Efficiency Efficiency (VIN=12V, VOUT=3.3V) (VIN=12V, VOUT=5.0V) Vin=12V 90% 80% 80% 70% 70% 60% 60% Efficiency(%) Efficiency(%) Vin=12V 90% 50% 40% 30% 50% 40% 30% 20% 20% 10% 10% 0% 0% 0.0 0.5 1.0 Iout(A) 1.5 2.0 0.0 0.5 1.0 Iout(A) 1.5 2.0 11/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008 AX3001 150KHz, 2A PWM Buck DC/DC Converter 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 12/12 Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.8 Mar.12, 2008