AP1551 150KHz, Dual Channel 2A PWM Buck DC/DC Converter Features General Description - Dual adjustable output channel - Adjustable output voltage range, 1.23V 18V+4% - 150KHz +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: 2A - SOP-16L Pb-Free packages - Low power standby mode - Built-in switching transistor on chip The AP1551 is monolithic IC designed for dual channel step-down DC/DC converters, and own the ability of driving a 2A load each channel without additional transistor component. 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 against 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 AP1551 operates at a switching frequency of 150KHz 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 16-lead SOP-16 package. to Applications - Simple High-efficiency step-down regulator - On-card switching regulators - Positive to negative converter Pin Assignments Pin Descriptions ( Top View ) Name Description VIN1/2 Operating voltage input GND2 1 16 GND2 GND2 2 15 GND2 SD2 3 14 FB2 VIN2 4 13 VOUT2 SD1 5 12 FB1 GND1/2 FB1/2 Output voltage feedback control SD1/2 ON/OFF Shutdown VIN1 6 11 VOUT1 GND1 7 10 GND1 GND1 8 9 GND1 VOUT1/2 Switching output Ground SOP-16L 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. 1.0 Nov 17, 2004 1/8 AP1551 150KHz, Dual Channel 2A PWM Buck DC/DC Converter Ordering Information AP 1551 X X Packing Package S: SOP-16L Blank : Tube A : Taping Block Diagram (Channel 1 and channel 2 are the same) SD1 VIN1 200mV Current Source bias 1.235V Reference 2.5V Regulator 220mV Start up + Comp _ _ Comp + FB1 Amp _ Frequecy compensation _ + Comp + Pre-driver 2A Switch VOUT1 150kHz OSC. Thermal Shutdown GND Anachip Corp. www.anachip.com.tw Rev. 1.0 Nov 17, 2004 2/8 AP1551 150KHz, Dual Channel 2A 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 Unless otherwise specified, VIN=12V, ILOAD = 0.5A Symbol Parameter IB1/2 Feedback bias current FOSC Oscillator frequency FSCP Oscillator frequency of short circuit protect VSAT1/2 Saturation voltage DC Max. Duty Cycle (ON) Min. Duty Cycle (OFF) ICL1/2 Current limit for each channel IL1/2 IQ1/2 ISTBY1/2 VIL1/2 VIH1/2 IH IL θJC θJA Output leakage Output = -1 current Quiescent Current Standby Quiescent Current Output = 0 ON/OFF pin logic input threshold voltage Conditions VFB1/2=1.3V (Adjustable version only) When current limit occurred and VFB1/2 < 0.5V, Ta=25 oC IOUT1/2=2A No outside circuit VFB1/2=0V force driver on VFB1/2=0V force driver on VFB1/2=12V force driver off Peak current No outside circuit VFB1/2=0V force driver on No outside circuit VFB1/2=12V force driver off VIN1/2=22V VFB1/2=12V force driver off ON/OFF pin=5V VIN1/2=22V Low (regulator ON) High (regulator OFF) ON/OFF pin logic input VLOGIC=2.5V (OFF) current ON/OFF pin input current VLOGIC=0.5V (ON) Junction to Thermal Resistance SOP-16L case Thermal Resistance Junction to With copper area of SOP-16L ambient 2 approximately 3 in Min. Typ. Unit 150 - Max. -50 -100 173 173 - -10 127 110 5 15 25 KHz - 1.25 - 100 0 - % 3 - - A - - -200 uA - -5 5 - 70 nA KHz 1.4 2.0 1.3 V 1.5 mA mA 10 150 200 0.6 uA V - - - -0.01 - -0.1 -1 - 15 - o - 70 - o uA C/W C/W Anachip Corp. www.anachip.com.tw Rev. 1.0 Nov 17, 2004 3/8 AP1551 150KHz, Dual Channel 2A PWM Buck DC/DC Converter Electrical Characteristics (Continued) Symbol AP1551-channel 1 AP1551-channel 2 Parameter Conditions Typ. Limit Unit VFB1 Output Feedback 4.5V < VIN < 22V 0.2A < ILOAD < 2A VOUT programmed for 3V 1.23 1.193/1.18 1.267/1.28 V VMIN VMAX η Efficiency VIN = 12V, ILOAD=2A VFB2 Output Feedback 4.5V < VIN < 22V 0.2A < ILOAD < 2A VOUT programmed for 3V η Efficiency VIN = 12V, ILOAD=2A 76 % 1.23 1.193/1.18 1.267/1.28 76 V VMIN VMAX % Specifications with boldface type are for full operating temperature range, the other type are for TJ=25ºC. Typical Application Circuit OFF ON 12V DC input OFF ON Cin 820uF 1 GND2 GND2 16 2 GND2 GND2 15 3 SD2 FB2 14 4 VIN2 VOUT2 13 5 SD1 FB1 12 6 VIN1 VOUT1 11 7 GND1 GND1 10 8 GND1 GND1 9 33uH 33uH 2.5V Vout1 R1 1.1k Ω R2 1kΩ Cout1 470uF 3.3V Vout2 R3 1.8kΩ R4 1kΩ Cout2 470uF R1 ); R2 R3 Vout2 =VFB × (1 + ); R4 VFB = 1.235V R2 = R4 = 1K ~ 3K Vout1 =VFB × (1 + Anachip Corp. www.anachip.com.tw Rev. 1.0 Nov 17, 2004 4/8 AP1551 150KHz, Dual Channel 2A PWM Buck DC/DC Converter Typical Performance Characteristics (For Each Channel) 86 85 84 83 82 81 80 79 78 77 76 75 -50 -30 -10 10 AP1551 Efficiency v.s. Temperature (Vin=12V,Vout=3.3V,Io=2A) 81 80 79 Efficiency (%) Efficiency (%) AP1551 Efficiency v.s. Temperature (Vin=12V,Vout=5V,Io=2A) 78 77 76 75 74 73 30 50 70 -50 -30 -10 10 90 110 130 150 Temperature (TA) (°C) AP1551 Saturation Voltage v.s. Temperature (Vcc=12V,Vfb=0V,VSD=0) 50 70 90 110 130 150 AP1551 Switch Current Limit v.s. Temperature (Vcc=12V,Vfb=0V) 1.4 Switch Current Limit (A) 5.5 1.3 Saturation Voltage (V) 30 Temperature (TA) (°C) 1.2 2A 1.1 1A 1 0.5A 0.9 0.8 0.7 -50 -25 0 25 50 75 100 5 4.5 4 3.5 3 -50 125 Temperature (TA) (°C) -30 -10 10 30 50 70 90 Temperature (TA) (°C) 15 14 13 12 11 10 9 8 7 6 5 60 Supply Current (uA) Supply Current (mA) AP1551 Supply Current v.s. Temperature (Vcc=12V , No Load ,Von/off =0V(Switch ON) ,Von/off =5V(Switch OFF)) Switch ON -50 -30 -10 10 30 50 70 90 110 130 150 55 50 45 Switch OFF 40 35 30 -50 -30 -10 10 30 50 70 90 110 130 150 Temperature (TA) (°C) Temperature (TA) (°C) Anachip Corp. www.anachip.com.tw Rev. 1.0 Nov 17, 2004 5/8 AP1551 150KHz, Dual Channel 2A PWM Buck DC/DC Converter Typical Performance Characteristics (For Each Channel) (Continued) AP1551 Threshold Voltage v.s. Temperature (Vcc=12V , Io=100mA) AP1551 ON/OFF Current v.s. ON/OFF Voltage (Vin=12V) 1.7 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 1.5 ON/OFF Current (nA) Threshold Voltage (V) 1.6 1.4 1.3 1.2 1.1 1 0.9 0.8 -50 -30 -10 10 30 50 70 0 90 110 130 150 Temperature (TA) (°C) 6 9 12 15 18 21 ON/OFF Voltage (V) AP1551 Frequency v.s. Temperature (Vcc=12V , Io=500mA ,Vout=5V) AP1551 Feedback Current v.s. Temperature (Vcc=12V , Vout=5V,Vfb=1.3V) 170 10 Feedback Current (nA) 165 Frequency (KHz) 3 160 155 150 145 140 0 -10 -20 -30 -40 -50 -50 -30 -10 10 30 50 70 90 110 130 150 -50 -30 -10 10 Temperature (TA) (°C) 30 50 70 90 110 130 150 Temperature (TA) (°C) Vout (V) AP1551 Output Voltage v.s. Temperature (Vin=12V ,Io=2A) 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 20 40 60 80 100 120 140 160 Temperature (TA) (°C) Anachip Corp. www.anachip.com.tw Rev. 1.0 Nov 17, 2004 6/8 AP1551 150KHz, Dual Channel 2A PWM Buck DC/DC Converter Function Description Thermal Considerations The SOP-16 package needs a heat sink under most conditions. The size of the heatsink depends on the input voltage, the output voltage, the load current and the ambient temperature. The AP1551 junction temperature rises above ambient temperature for each channel with a 2A load and different input and output voltages. The data for these curves was taken with the AP1551 (SOP-16 package) operating as a buck-switching regulator in an ambient temperature 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. Pin Functions +VIN1/2 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. Ground1/2 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. For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper should be used in the board layout. (Once exception to this is the output (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. Feedback1/2 Senses the regulated output voltage to complete the feedback loop. SD1/2 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 feature is not needed, the SD pin can be wired to the ground pin or it can be left open, in either case the regulator will be in the ON condition. Package thermal resistance and junction temperature rise numbers are all approximate, and there are many factors that will affect these numbers. 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. Anachip Corp. www.anachip.com.tw Rev. 1.0 Nov 17, 2004 7/8 AP1551 150KHz, Dual Channel 2A PWM Buck DC/DC Converter Marking Information SOP-16L ( Top View ) 9 16 Logo AP1551 YY WW X Part No. 1 ID code: internal Xth week: 01~52 Year: "01" = 2001 "02" = 2002 8 ~ SOP-16L Package Information E H Package Type: SOP-16L θ L VIEW "A" D 7o(4X) y Symbol A A1 A2 B C D E e H L θ Dimensions In Millimeters Min. Nom. Max. 1.40 1.60 1.75 0.10 0.25 1.30 1.45 1.50 0.33 0.41 0.51 0.19 0.20 0.25 9.80 9.90 10.00 3.80 3.90 4.00 1.27 5.80 6.00 6.20 0.38 0.71 1.27 0 8 Anachip Corp. www.anachip.com.tw C B A1 e 7o(4X) A A2 0.015x45o VIEW "A" Dimensions In Inches Min. Nom. Max. 0.055 0.063 0.069 0.040 0.010 0.051 0.057 0.059 0.013 0.016 0.020 0.0075 0.008 0.0098 0.386 0.390 0.394 0.154 0.150 0.157 0.050 0.228 0.236 0.244 0.015 0.028 0.050 0 8 Rev. 1.0 Nov 17, 2004 8/8