PWM Buck DC/DC Converter

www.DataSheet4U.com AP1518 300KHz, 3A PWM Buck DC/DC Converter Features - Adjustable version output voltage range, 0.8V to 18V+4% - 300KHz +15% fixed switching frequency - Voltage mode non-synchronous PWM control - Thermal-shutdown and current-limit protection - ON /OFF shutdown control input - Operating voltage can be up to 22V - Output load current: 3A - TO220-5L and TO263-5L Pb-Free packages - Low power standby mode - Built-in switching transistor on chip General Description The AP1518 series are monolithic IC designed for a step-down DC/DC converter, and own the ability of driving a 3A load without external transistor. Due to reducing the number of external component, the board space can be saved easily. The external shutdown function can be controlled by logic level and then come into standby mode. The internal compensation makes feedback control have 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 to prevent over current operating of the output switch. If current limit function occurred and VFB is down to 0.5V below, the switching frequency will be reduced. The AP1518 series operate at a switching frequency of 300KHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Other features include a guaranteed +4% tolerance on output voltage under specified input voltage and output load conditions, and +15% on the oscillator frequency. The packages are available in a standard 5-lead TO-220 package or a 5-lead TO-263. Applications - Simple High-efficiency step-down regulator - On-card switching regulators - Positive to negative converter Pin Assignments ( Top View ) 5 SD 4 FB 3 Gnd 2 Output 1 VIN Pin Descriptions Name VIN Output GND FB SD Description Operating voltage input Switching output Ground Output voltage feedback control ON /OFF Shutdown Metal Tab GND TO263-5L ( Top View ) 5 SD 4 FB 3 Gnd 2 Output 1 VIN TO220-5L This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sale of the product. Rev.1.1 Oct 29, 2004 1/12 AP1518 300KHz, 3A PWM Buck DC/DC Converter Ordering Information AP1518 X X Packing Blank : Tube A : Taping Package T5: TO220-5L K5: TO263-5L T5R: TO220-5L(R) Block Diagram SD VIN 200mV Current Source bias 0.8V Reference 2.5V Regulator Start up 220mV Comp _ + Comp + FB _ Comp + Anachip Corp. www.anachip.com.tw 2/12 _ Amp + Frequecy compensation Pre-driver 300kHz OSC. Thermal Shutdown _ 3A Switch Output Gnd Rev.1.1 Oct 29, 2004 AP1518 300KHz, 3A PWM Buck DC/DC Converter Absolute Maximum Ratings Symbol VCC VSD VFB VOUT PD TST TOP VOP Parameter Supply Voltage ON /OFF Pin input voltage Feedback Pin voltage Output voltage to Ground Power dissipation Storage temperature Operating temperature Operating voltage Rating +24 -0.3 to +18 -0.3 to +18 -1 Internally limited -65 to +150 -40 to +125 +4.5 to +22 Unit V V V V W o C o C V Electrical Characteristics (All Output Voltage Versions) Unless otherwise specified, VIN=12V, ILOAD = 0.5A Symbol IFB FOSC FSCP VSAT DC ICL IL IQ ISTBY VIL VIH IH IL ΘJC ΘJA Parameter Feedback bias current Oscillator frequency Conditions VFB=0.8V (Adjustable version only) Min. 255 220 10 Typ. -10 300 30 1.4 100 0 Max. -50 -100 345 345 50 1.6 1.7 Unit nA KHz KHz V % of When current limit occurred o and VFB < 0.5V, Ta=25 C IOUT=3A Saturation Voltage No outside circuit VFB=0V force driver on Max. Duty Cycle (ON) VFB=0V force driver on Min. Duty Cycle (OFF) VFB=12V force driver off Peak current Current limit No outside circuit VFB=0 force driver on Output No outside circuit Output = 0V leakage VFB=12 force driver off current VIN=22V Output =-1V Quiescent Current VFB=12 force driver off Standby Quiescent ON /OFF pin=5V Current VIN=22V Low (regulator ON) ON /OFF pin logic input High (regulator OFF) threshold voltage ON /OFF pin logic input current ON /OFF pin input current Oscillator frequency short circuit protect 5.5 3.6 4.5 6.5 -200 -5 5 70 2.0 1.3 10 150 200 0.6 -0.01 uA -0.1 2.5 3.5 28 23 -1 o A uA mA mA uA V VLOGIC=2.5V (OFF) VLOGIC=0.5V (ON) TO220-5L TO263-5L TO220-5L TO263-5L Junction to case Junction to ambient Thermal Resistance Thermal Resistance With copper area of approximately 3 in2 C/W C/W o Specifications with boldface type are for full operating temperature range, the other type are for TJ=25ºC. Anachip Corp. www.anachip.com.tw 3/12 Rev.1.1 Oct 29, 2004 AP1518 300KHz, 3A PWM Buck DC/DC Converter Electrical Characteristics (Continued) Sym. VFB Parameter Output Feedback Efficiency Efficiency Efficiency Efficiency Conditions 5V < VIN < 22V 0.2A < ILOAD < 3A VOUT programmed for 3V VIN = 12V, ILOAD=3A VOUT programmed for 3.3V VIN = 12V, ILOAD=3A VOUT programmed for 5V VIN = 12V, ILOAD=3A VOUT programmed for 12V VIN = 16V, ILOAD = 3A Typ. 0.8 74 75 80 89 Limit 0.784/0.768 0.816/0.832 Unit V VMIN VMAX % % % % η AP1518 η η η Specifications with boldface type are for full operating temperature range, the other type are for TJ=25ºC. Anachip Corp. www.anachip.com.tw 4/12 Rev.1.1 Oct 29, 2004 AP1518 300KHz, 3A PWM Buck DC/DC Converter Typical Performance Characteristics AP1518 Efficiency v.s. Temperature (Vin=12V,Vout=5V,Io=3A) 83 82 81 80 79 78 77 76 75 74 73 72 -50 -30 -10 10 30 50 70 90 110 130 150 AP1518 Efficiency v.s. Temperature (Vin=12V,Vout=3.3V,Io=3A) 78 77 76 Efficiency (%) Efficiency (%) 75 74 73 72 71 70 -50 -30 -10 10 30 50 70 90 110 130 150 Temperature (TA) (°C) Temperature (TA) (°C) AP1518 Saturation Voltage v.s. Temperature (Vcc=12V,Vfb=0V,VSD=0) 1.6 1.5 AP1518 Switch Current Limit v.s. Temperature (Vcc=12V,Vfb=0V) 5.5 Saturation Voltage (V) 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 -50 -25 0 25 1A 0.5A 3A 2A Switch Current Limit (A) 5 4.5 4 3.5 3 -50 -30 -10 10 30 50 70 90 50 75 100 125 Temperature (TA)　(°C) Temperature (TA) (°C) AP1518 Supply Current v.s. Temperature (Vcc=12V , No Load ,Von/off =0V(Switch ON) ,Von/off =5V(Switch OFF)) 15 14 13 12 11 10 9 8 7 6 5 60 Supply Current (mA) Supply Current (uA) 55 50 45 40 35 30 -50 -30 -10 10 30 50 70 90 110 130 150 Switch OFF Switch ON -50 -30 -10 10 30 50 70 90 110 130 150 Temperature (TA) (°C) Temperature (TA) (°C) Anachip Corp. www.anachip.com.tw 5/12 Rev.1.1 Oct 29, 2004 AP1518 300KHz, 3A PWM Buck DC/DC Converter Typical Performance Characteristics (Continued) AP1518 Threshold Voltage v.s. Temperature (Vcc=12V , Io=100mA) 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8 -50 -30 -10 10 30 50 70 90 110 130 150 AP1518 ON/OFF Current v.s. ON/OFF Voltage (Vin=12V) 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 0 3 6 9 12 15 18 21 Threshold Voltage (V) Temperature (TA) (°C) ON/OFF Current (nA) ON/OFF Voltage (V) AP1518 Frequency v.s. Temperature (Vcc=12V , Io=500mA ,Vout=5V) 320 AP1518 Feedback Current v.s. Temperature (Vcc=12V , Vout=5V,Vfb=0.8V) 10 300 290 280 270 260 -50 -30 -10 10 30 Feedback Current (nA) 50 70 90 110 130 150 310 0 -10 -20 -30 -40 -50 -50 -30 -10 10 Frequency (KHz) Temperature (TA) (°C) Temperature (TA) (°C) 30 50 70 90 110 130 150 AP1518 Output Voltage v.s. Temperature (Vin=12V ,Io=3A) 3.5 3.45 3.4 3.35 3.3 3.25 3.2 3.15 3.1 3.05 3 2.95 2.9 -40 -20 0 Vout (V) Temperature (TA) (°C) 20 40 60 80 100 120 140 160 Anachip Corp. www.anachip.com.tw 6/12 Rev.1.1 Oct 29, 2004 AP1518 300KHz, 3A PWM Buck DC/DC Converter Typical Application Circuit (1) Normal Circuit R2 FB 12V DC Input Vin Cin Capacitor 4 1 AP1518 5 SD 3 Gnd D1 Schottky Diode Co Capacitor 2 Output L1 10uH 1V/ 2A Output Load R1 Vout = VFB × (1 + VFB = 0.8V R2 = 1K ~ 3K (2) Delay Start Circuit R2 FB 12V DC Input Vin Cin Capacitor CDELAY 0.1uF 4 1 5 SD RDELAY 10K AP1518 3 2 R1 R2 ) R1 Output L1 10uH 1V/ 2A Output Load Gnd D1 Schottky Diode Co Capacitor Anachip Corp. www.anachip.com.tw 7/12 Rev.1.1 Oct 29, 2004 AP1518 300KHz, 3A PWM Buck DC/DC Converter Function Description Pin Functions +VIN This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be present at this pin to minimize voltage transients and to supply the switching currents needed by the regulator. Ground Circuit ground. Output Internal switch. The voltage at this pin switches between (+VIN – VSAT) and approximately – 0.5V, with a duty cycle of approximately VOUT / VIN. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin should be kept a minimum. Feedback (FB) Senses the regulated output voltage to complete the feedback loop. ON /OFF (SD) Allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total input supply current to approximately 150uA. 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 18V) shuts the regulator down. If this shutdown of 25oC (still air). These temperature rise numbers are all approximate and there are many factors that can affect these temperatures. Higher ambient temperatures require more heat sinking. The TO-263 surface mount package tab was designed to be soldering to the copper on a printed circuit board. The copper and the board are the heat sink for this package and the other heat producing components, such as the catch diode and inductor. The PC board copper area that the package is soldered to should be at least 0.8 in2, and ideally should have 2 or more square inches of 2 oz. Additional copper area improves the thermal characteristics, but with copper areas greater than approximately 6 in2, only small improvements in heat dissipation are realized. If further thermal improvements are needed, double sided, multi-layer PC board with