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| AP1551 150KHz, Dual Channel 2A PWM Buck DC/DC Converter Features - 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 to General Description 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. Applications - Simple High-efficiency step-down regulator - On-card switching regulators - Positive to negative converter Pin Assignments ( Top View ) GND2 GND2 SD2 VIN2 SD1 VIN1 GND1 GND1 1 2 3 4 5 6 7 8 16 GND2 15 GND2 14 13 12 11 10 9 Pin Descriptions Name VIN1/2 VOUT1/2 GND1/2 FB1/2 SD1/2 Description Operating voltage input Switching output Ground Output voltage feedback control ON/OFF Shutdown FB2 VOUT2 FB1 VOUT1 GND1 GND1 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 Package S: SOP-16L Packing 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 Start up 220mV Comp _ + Comp + + + Anachip Corp. www.anachip.com.tw Rev. 1.0 Nov 17, 2004 2/8 _ FB1 _ Amp Frequecy compensation Comp Pre-driver 150kHz OSC. Thermal Shutdown _ 2A Switch VOUT1 GND 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 IB1/2 FOSC FSCP VSAT1/2 DC ICL1/2 IL1/2 IQ1/2 ISTBY1/2 VIL1/2 VIH1/2 IH IL JC JA Parameter Feedback bias current Oscillator frequency Oscillator frequency of short circuit protect Saturation voltage Max. Duty Cycle (ON) Min. Duty Cycle (OFF) Current limit for each channel 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) Min. 127 110 Typ. -10 150 15 1.25 100 0 -5 5 70 1.3 -0.1 15 70 Max. -50 -100 173 173 25 1.4 1.5 -200 10 150 200 0.6 -0.01 -1 - Unit nA KHz KHz V % A uA mA mA uA V uA o 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) 5 3 2.0 - 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 C/W C/W o 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 VFB1 Parameter Output Feedback Efficiency Output Feedback Efficiency Conditions 4.5V < VIN < 22V 0.2A < ILOAD < 2A VOUT programmed for 3V VIN = 12V, ILOAD=2A 4.5V < VIN < 22V 0.2A < ILOAD < 2A VOUT programmed for 3V VIN = 12V, ILOAD=2A Typ. 1.23 76 1.23 76 1.193/1.18 1.267/1.28 Limit 1.193/1.18 1.267/1.28 Unit V VMIN VMAX % V VMIN VMAX % AP1551-channel 1 VFB2 AP1551-channel 2 Specifications with boldface type are for full operating temperature range, the other type are for TJ=25C. Typical Application Circuit 1 OFF ON 12V DC input OFF ON 2 3 4 5 6 7 Cin 820uF 8 GND2 GND2 SD2 VIN2 SD1 VIN1 GND1 GND1 GND2 16 GND2 15 FB2 14 VOUT2 13 FB1 12 VOUT1 11 GND1 10 GND1 9 33uH 2.5V Vout1 R1 1.1k R2 1k Cout1 470uF 33uH 3.3V Vout2 R3 1.8k R4 1k Cout2 470uF R1 ); R2 R3 Vout2 =VFB x (1 + ); R4 VFB = 1.235V R2 = R4 = 1K ~ 3K Vout1 =VFB x (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) AP1551 Efficiency v.s. Temperature (Vin=12V,Vout=5V,Io=2A) 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 (%) 78 77 76 75 74 73 -50 -30 -10 10 30 50 70 90 110 130 150 30 50 70 90 110 130 150 Temperature (TA) (C) Temperature (TA) (C) AP1551 Saturation Voltage v.s. Temperature (Vcc=12V,Vfb=0V,VSD=0) 1.4 1.3 AP1551 Switch Current Limit v.s. Temperature (Vcc=12V,Vfb=0V) 5.5 Switch Current Limit (A) Saturation Voltage (V) 1.2 1.1 1 0.9 0.8 0.7 -50 -25 0 25 1A 0.5A 5 4.5 4 3.5 3 -50 -30 -10 10 30 50 70 90 2A 50 75 100 125 Temperature (TA)(C) Temperature (TA) (C) AP1551 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 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) 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 AP1551 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) AP1551 Frequency v.s. Temperature (Vcc=12V , Io=500mA ,Vout=5V) 170 AP1551 Feedback Current v.s. Temperature (Vcc=12V , Vout=5V,Vfb=1.3V) 10 Frequency (KHz) 160 155 150 145 140 -50 -30 -10 10 30 50 70 90 110 130 150 Feedback Current (nA) 165 0 -10 -20 -30 -40 -50 -50 -30 -10 10 30 50 70 90 110 130 150 Temperature (TA) (C) Temperature (TA) (C) 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 Vout (V) Temperature (TA) (C) 0 20 40 60 80 100 120 140 160 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 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. 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. 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. 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. 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 ) 16 9 Logo Part No. AP1551 YY WW X 1 8 ID code: internal Xth week: 01~52 Year: "01" = 2001 "02" = 2002 ~ SOP-16L Package Information Package Type: SOP-16L E H L VIEW "A" 7o(4X) D 0.015x45o A2 A 7o(4X) A1 y Symbol A A1 A2 B C D E e H L Anachip Corp. www.anachip.com.tw 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 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 C e B VIEW "A" Rev. 1.0 Nov 17, 2004 8/8 |
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