Macroblock MBI6650 Preliminary Datasheet 1.2A DC/DC Converter Features Surface Mount Device z 1.2A Constant Output Current z 93% Efficiency @ input voltage 13V, 350mA, 3-LED z 9~36V Input Voltage Range z Hysteretic PFM Improves Efficiency at Light Loads z Settable Output Current z Integrated Power Switch z Full Protection: Thermal/UVLO/Soft Start/LED Open-/Short- Circuit z Only 4 External Components Required PSD: TO-252-5L Product Description The MBI6650 is a high efficiency, constant current, step-down DC/DC converter, designed to deliver constant current to high power LED with only 4 external components. The MBI6650 is specifically designed with hysteretic PFM control scheme to enhance the efficiency up to 93%. Output current of the MBI6650 can be programmed by an external resistor, and LED dimming can be controlled via pulse width modulation (PWM) through DIM pin. In addition, the embedded soft start function eliminates the inrush current while the power is on. The MBI6650 also features under voltage lock out (UVLO), over temperature protection, LED open-circuit protection and LED short-circuit protection to protect IC from being damaged. Additionally, to ensure the system reliability, the MBI6650 is built with the thermal protection (TP) function and a thermal pad. The TP function protects IC from over temperature (140°C). Also, the thermal pad enhances the power dissipation. As a result, a large amount of current can be handled safely in one package. Applications z Signage and Decorative LED Lighting z Automotive LED Lighting z High Power LED Lighting z Constant Current Source Macroblock, Inc. 2007 Floor 6-4, No.18, Pu-Ting Rd., Hsinchu, Taiwan 30077, ROC. TEL: +886-3-579-0068, FAX: +886-3-579-7534 E-mail: [email protected] -1October 2007, V1.00 MBI6650 1.2A DC/DC Converter Typical Application Circuit RSEN + VSEN - VIN CIN VIN SEN DIM 10uF/50V GND + D1 COUT VOUT 10uF/50V MBI6650 + + IOUT L1 SW - 47uH CIN: VISHAY, 293D106X9050D2TE3, D case Tantalum Capacitor COUT: VISHAY, 293D106X9050D2TE3, D case Tantalum Capacitor L1: GANG SONG, GSRH8D43-470M D1: ZOWIE, SSCD206 Figure 1 Functional Diagram VIN Bias 1.24V SEN Comp Thermal Shutdown Vref DIM Digital Comp SW Driver GND Figure 2 -2- October 2007, V1.00 MBI6650 1.2A DC/DC Converter Pin Configuration Pin Description Pin Name Function GND Ground terminal for control logic and current sink SW Switch output terminal DIM Dimming control terminal SEN Output current sense terminal VIN Supply voltage terminal Thermal Pad Power dissipation terminal connected to GND* *To eliminate the noise influence, the thermal pad is suggested to be connected to GND on PCB. In addition, the desired thermal conductivity will be improved, when a heat-conducting copper foil on PCB is soldered with thermal pad. Maximum Ratings Operation above the maximum ratings may cause device failure. Operation at the extended periods of the maximum ratings may reduce the device reliability. Characteristic Symbol Rating Unit Supply Voltage VIN 0~40 V Output Current IOUT 1.2 A Sustaining Voltage at SW pin VSW -0.5~45 V GND Terminal Current IGND 1.2 A Power Dissipation (On 4 Layer PCB, Ta=25°C)* PD 3.80 W Thermal Resistance (By simulation, on 4 Layer PCB) 32.9 PSD Type Rth(j-a) Empirical Thermal Resistance (On 4 Layer PCB, Ta=25°C)* °C/W 50.54 Operating Junction Temperature Tj,max 125 °C Operating Temperature Topr -40~+85 °C Storage Temperature Tstg -55~+150 °C *The PCB area is 7 times larger than that of IC’s, and the heat sink area of MBI6650 is 109mm2. Please refer to Figure 38 for the PCB layout. -3- October 2007, V1.00 MBI6650 1.2A DC/DC Converter Electrical Characteristics (Test condition: VIN=12V, L1=47µH, CIN=COUT=10µF, TA=25°C; unless otherwise specified; refer to test circuit (a)) Characteristics Symbol Condition Min. Typ. Max. Unit Supply Voltage VIN 9 36 V Supply Current IIN VIN=9V~36V 1 4 mA Output Current IOUT 350 1200 mA 150mA≤IOUT≤750mA, ±5 ±10 % Output Current Accuracy dIOUT/IOUT ±5 ±10 75mA≤IOUT≤1200mA, SW Dropout Voltage △VSW IOUT=1.2A 0.3 0.6 V 9V≤VIN≤36V, VOUT=3.6V, Line Regulation %/△VIN ±0.30 ±0.37 %/V IOUT=350mA VIN=24V, IOUT=350mA, ±0.24 ±1.38 3.6V≤VOUT≤18V VIN=24V, IOUT=700mA, %/V Load Regulation %/△V ±0.24 ±1.50 3.6V≤VOUT≤18V VIN=24V, IOUT=1200mA, ±0.24 ±1.80 3.6V≤VOUT≤18V Efficiency VIN=13V, IOUT=350mA, VOUT=10.8V 93 % “H” level VIH 3.5 V Input Voltage 1.5 V “L” level VIL Switch ON resistance Rds(on) VIN=12V; refer to test circuit (b) 0.8 1.1 Ω CURRENT SENSE VSEN Production code “A” * 0.28 Regulated RSEN Voltage V VSEN Production code “B” * 0.33 THERMAL OVERLOAD Thermal Shutdown TSD +130 +140 +155 °C Threshold Thermal Shutdown TSD-HYS 40 45 55 °C Hystersis UNDER VOLTAGE LOCK OUT UVLO Voltage TA=-40~85°C 6.6 7.4 7.9 V UVLO Hysteresis 0.5 0.6 1 V Start Up Voltage 7.3 8.0 8.8 V DIMMING Rise Time of Output VOUT=3.6V, IOUT=350mA, fDIM=1kHz, tr 140 µs Current DutyDIM=50% VOUT=3.6V, IOUT=350mA, fDIM=1kHz, 160 µs Fall Time of Output Current tf DutyDIM=50% *Refer to Product Top-Mark Information. Test Circuit for Electrical Characteristics D1 SW SEN VSW RSEN VIN COUT Electronic Load CIN SW MBI6650 Ω DIM VIN DIM GND SEN L1 MBI6650 VIN VIN VIH GND VIL (a) (b) Figure 3 -4- October 2007, V1.00 MBI6650 1.2A DC/DC Converter Typical Performance Characteristics Please refer to Typical Application Circuit, VIN=12V, L1=47uH, CIN=COUT=10uF, TA=25°C, unless otherwise specified. 1-LED VF=3.6V; 2-LED VF=7.2V; 3-LED VF=10.8V; 4-LED VF=14.4V; 5-LED VF=18V 1. Efficiency vs. Input Voltage at Various Load Current 100 95 1-LED 90 2-LED 3-LED 85 4-LED 80 5-LED 95 Efficiency (%) Efficiency (%) 100 2-LED 85 75 3-LED 80 4-LED 75 5-LED 70 70 9 12 15 18 21 24 Input Voltage (V) 27 30 33 9 36 12 15 18 21 24 27 30 33 36 Input Voltage (V) Figure 4. Efficiency vs. VIN @ 350mA, L1=47uH Figure 5. Efficiency vs. VIN @ 700mA, L1=47uH 95 95 90 85 1-LED 80 2-LED 75 3-LED 70 65 4-LED 90 Efficiency (%) Efficiency (%) 1-LED 90 5-LED 12 15 18 21 24 27 30 33 2-LED 80 3-LED 75 4-LED 70 5-LED 65 60 9 1-LED 85 60 36 9 12 15 18 21 24 Input Voltage (V) Input Voltage (V) Figure 6. Efficiency vs. VIN @ 1000mA, L1=47uH 27 30 33 36 Figure 7. Efficiency vs. VIN @ 1200mA, L1=47uH 2. Line Regulation 750 375 370 1-LED 365 2-LED 360 3-LED 355 4-LED 350 5-LED Output Current (mA) Output Current (mA) 380 345 1-LED 720 2-LED 710 700 3-LED 690 680 5-LED 4-LED 670 340 9 12 15 18 21 24 Input Voltage (V) 27 30 33 9 36 12 15 18 21 24 27 30 33 36 Input Voltage (V) Figure 8. Line regulation @ 350mA, L1=47uH Figure 9. Line regulation @ 700mA, L1=47uH 1150 1450 1100 Output Current (mA) Output Current (mA) 740 730 1-LED 2-LED 1050 3-LED 4-LED 1000 5-LED 950 1400 1-LED 1350 2-LED 1300 3-LED 1250 4-LED 1200 5-LED 1150 1100 9 12 15 18 21 24 Input Voltage (V) 27 30 Figure 10. Line regulation @ 1000mA, L1=47uH 33 36 9 12 15 18 21 24 Input Voltage (V) 27 30 33 36 Figure 11. Line regulation @ 1200mA, L1=47uH -5- October 2007, V1.00 MBI6650 1.2A DC/DC Converter 3. Load Regulation 350 Output Current (mA) Output Current (mA) 360 Vin=12V 340 Vin=24V Vin=36V 330 320 310 1 2 3 LED (#) 4 Vin=12V 690 Vin=24V 685 Vin=36V 680 675 670 665 1 5 Figure 12. Load regulation @ 350mA, L1=47uH 2 3 LED (#) 4 5 Figure 13. Load regulation @ 700mA, L1=47uH 1250 1000 980 Vin=12V 960 Vin=24V 940 Vin=36V 920 900 Output Current (mA) 1020 Output Current (mA) 705 700 695 880 1200 1150 Vin=12V 1100 Vin=24V 1050 Vin=36V 1000 950 1 2 3 LED (#) 4 5 1 Figure 14. Load regulation @ 1000mA, L1=47uH 2 3 LED (#) 4 5 Figure 15. Load regulation @ 1200mA, L1=47uH 600 350 300 250 200 150 100 50 0 Iout=350mA Iout=700mA Iout=1000mA Iout=1200mA F requenc y (k H z ) F requenc y (k H z ) 4. Switching Frequency 500 Iout=350mA 400 Iout=700mA 300 Iout=1000mA 200 Iout=1200mA 100 0 9 12 15 18 21 24 27 30 33 9 36 12 15 18 24 27 30 33 36 Figure 17. Switching frequency @ 2-LED, L1=47uH 800 700 600 500 400 300 200 100 0 Iout=350mA Iout=700mA Iout=1000mA Iout=1200mA F requenc y (k H z ) F requenc y (k H z ) Figure 16. Switching frequency @ 1-LED, L1=47uH 600 Iout=350mA Iout=700mA 400 Iout=1000mA 200 Iout=1200mA 0 9 12 15 18 21 24 27 30 33 15 36 18 21 24 27 30 33 36 Input Voltage (V) Input Voltage (V) Figure 18. Switching frequency @ 3-LED, L1=47uH Figure 19. Switching frequency @ 4-LED, L1=47uH VIN=12V, Iout=350mA 360 800 350 600 Iout=350mA Iout=700mA 400 Iout=1000mA 200 Iout=1200mA 0 18 21 24 27 30 33 SwitchingFrequency(kHz F requenc y (k H z ) 21 Input Voltage (V) Input Voltage (V) 330 320 310 300 36 290 Input Voltage (V) Figure 20. Switching frequency @ 5-LED, L1=47uH 340 -40 -15 10 35 Temperature (℃) 60 85 Figure 21. Switching frequency vs. temperature -6- October 2007, V1.00 MBI6650 1.2A DC/DC Converter 5. Miscellaneous 40 350 300 fDIM=100Hz 250 fDIM=300Hz Output Current (mA) Output Current (mA) 400 fDIM=500Hz 200 fDIM=700Hz 150 fDIM=1000Hz 100 50 35 30 fDIM=100Hz 25 fDIM=300Hz fDIM=500Hz 20 fDIM=700Hz 15 fDIM=1000Hz 10 5 0 0 0 10 20 30 40 50 60 Duty Cycle (%) 70 80 90 100 0 1 2 3 4 5 6 Duty Cycle (%) 7 8 9 10 Figure 23. Output current vs. DIM duty cycle @ 1-LED, IOUT=350mA IOUT=350mA 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0.90 Quiescent Current (mA) Rds (on) (Ω) Figure 22. Output current vs. DIM duty cycle @ 1-LED, 9 12 15 18 21 24 27 30 33 0.85 0.80 0.75 0.70 0.65 0.60 36 9 Input Voltage (V) 15 18 21 24 Input Voltage (V) 27 30 33 36 Figure 25. Quiescent current vs. VIN 0.90 365 0.85 360 O utput Current (m A) Shutdown Current (mA) Figure 24. Rds (on) vs. VIN 12 0.80 0.75 0.70 0.65 VIN=12V, Iout=350mA 355 350 345 340 0.60 9 12 15 18 21 24 27 Input Voltage (V) 30 33 335 36 -40 Figure 26. Shutdown current vs. VIN -15 10 35 Temperature (℃) 60 85 Figure 27. Output current vs. temperature VIN=12V, Iout=350mA 0.325 0.32 0.315 VSEN(V) 0.31 0.305 0.3 0.295 0.29 0.285 0.28 0.275 -40 -15 10 35 Temperature (℃) 60 85 Figure 28. VSEN vs. temperature VSW VIN VSEN (Attenuation Ratio: 1/20) VSW IOUT IOUT Figure 29. Start-up waveform @ VOUT=7.2V, IOUT=350mA Figure 30. Switching waveform @ VOUT=3.6V, IOUT=350mA -7- October 2007, V1.00 MBI6650 1.2A DC/DC Converter VIN VSW VIN VOUT (Attenuation Ratio: 1/20) VOUT (Attenuation Ratio: 1/20) IL VSW IL Figure 31. Open-circuit protection waveform Figure 32. Short -circuit protection waveform @ IOUT=350mA @IOUT=350mA SW SW IOUT DIM DIM IOUT Figure 33. Rise time of output current @ 1-LED, Figure 34. Fall time of output current @ 1-LED, IOUT=350mA, tr=140µs IOUT=350mA, tr=160µs SW VIN VSW DIM VOUT (Attenuation Ratio: 1/20) IOUT IOUT Figure 36. Thermal protection Figure 35. Dimming waveform @ 1-LED, IOUT=350mA, fDIM=100Hz, DutyDIM=10% -8- October 2007, V1.00 MBI6650 1.2A DC/DC Converter Application Information The MBI6650 is embedded with all the features to implement a simple, cost effective, and high efficient buck converter to drive more than 1A of loading. The MBI6650 contains an N-Channel switch, is easy to implement, and is available in the thermally enhanced TO252-5L package. The MBI6650’s operation is based on a hysteretic PFM control scheme resulting in the operating frequency remaining relatively constant with load and input voltage variations. The hysteretic PFM control requires no loop compensation resulting in very fast load transient response and achieving excellent efficiency performance at light loading. Setting Output Current The output current (IOUT) is set by an external resistor, RSEN. The relationship between IOUT and RSEN is as below; for production code information, please refer to Product Top-Mark Information: For production code A, VSEN=0.28V; RSEN=(VSEN/IOUT)=(0.28V/IOUT); IOUT=(VSEN/RSEN)=(0.28V/RSEN) where RSEN is the resistance of the external resistor connected to SEN terminal and VSEN is the voltage of external resistor. The magnitude of current (as a function of RSEN) is around 1000mA at 0.28Ω. For production code B, VSEN=0.33V; RSEN=(VSEN/IOUT)=(0.33V/IOUT); IOUT=(VSEN/RSEN)=(0.33V/RSEN) where RSEN is the resistance of the external resistor connected to SEN terminal and VSEN is the voltage of external resistor. The magnitude of current (as a function of RSEN) is around 1000mA at 0.33Ω. Minimum Input Voltage The minimum input voltage is the sum of the voltage drops on RSEN, RS, DCR of L1, Rds(on) of internal MOSFET and the total forward voltage of LEDs. The dynamic resistance of LED, RS, is the inverse of the slope in linear forward voltage model for LED. This electrical characteristic can be provided by LED manufacturers. The equivalent impedance of the MBI6650 application circuit is shown as in Figure 36. As the input voltage is smaller than minimum input voltage, which is pointed out by MBI6650 Design Tool, the output current will be larger than the present output current, and is limited to 1.3 times of preset one. For detailed information, please refer to the MBI6650 Application Note V1.00. -9- October 2007, V1.00 MBI6650 1.2A DC/DC Converter RSEN VIN SEN Schottky Diode Equivalent Circuit MBI6650 Rs VF,D1 VF,LED SW Rds(on) LED Equivalent Circuit DCR Inductor Equivalent Circuit GND Figure 37. The equivalent impedance in a MBI6650 application circuit Dimming The dimming of LEDs can be performed by applying PWM signals to DIM pin. A logic low (below 1.5V) at DIM will disable the internal MOSFET and shut off the current flow to the LED array. An internal pull-up circuit ensures that the MBI6650 is on when DIM pin is unconnected, eliminating the need for an external pull-up resistor. LED Open-Circuit Protection When any LED connected to the MBI6650 is open-circuit, output current of the MBI6650 will be turned off. LED Short-Circuit Protection When any LED connected to the MBI6650 is short-circuit, output current of the MBI6650 will still be limited to its preset value. Under Voltage Lock Out Protection When the voltage at VIN of the MBI6650 is below 7.4V, output current of the MBI6650 will be turned off. When VIN voltage of the MBI6650 resumes to 8.0V, output current of the MBI6650 will be turned on again. Internal Soft Start Protection With embedded soft start function inside the MBI6650, output ripple of the MBI6650 can be eliminated. - 10 - October 2007, V1.00 MBI6650 1.2A DC/DC Converter TP Function (Thermal Protection) When the junction temperature exceeds the threshold, TX (140°C), TP function turns off the output current. Thus, the junction temperature starts to decrease. As soon as the temperature is below 140°C, the output current will be turned on again. The on-state and off-state switch are at a high frequency; thus, the blinking is imperceptible. However, the average output current is limited, and therefore, the driver is protected from being overheated. Inductor Selection The inductance is determined by two factors: the switching frequency and the inductor ripple current. The calculation of the inductance, L1, can be described as L1 > ( VIN - VOUT - VSEN - (R ds(on) x IOUT )) x D fSW x ∆IL where Rds(on) is the on-resistance of internal MOSFET of the MBI6650. The typical is 0.8Ω at 12VIN. D is the duty cycle of the MBI6650, D=VOUT/VIN. fSW is the switching frequency of the MBI6650. △IL is the ripple current of inductor, △IL=(1.3xIOUT)–(0.7xIOUT)=0.6xIOUT. When selecting an inductor, the inductance is not the only factor to affect the performance of module, but the saturation current also needs to be considered. In general, it is recommended to choose an inductor with 1.5 times of LED current as the saturation current. Also, the larger inductance gains the better line/load regulation. However, when at the same inductor size, the inductance and saturation current becomes a trade-off. An inductor with shield is recommended to reduce the EMI interference, but this is another trade-off with heat dissipation. Schottky Diode Selection The MBI6650 needs a flywheel diode, D1, to carry the inductor current when the MOSFET is off. The recommended flywheel diode is schottky diode with low forward voltage for better efficiency. Two factors determine the selection of schottky diode. One is the maximum reverse voltage, and the recommended rated voltage of the reverse voltage is at least 1.5 times of input voltage. The other is the maximum forward current, which works when the MOSFET is off, and the recommended forward current is 1.5 times of output current. Input Capacitor Selection The input capacitor, CIN, can supply pulses of current for the MBI6650 when the MOSFET is on, and CIN is charged by input voltage when the MOSFET is off. As the input voltage is lower than the tolerable input voltage, the internal MOSFET of the MBI6650 becomes constantly “on”, and the LED current is limited to 1.3 times of normal current. Therefore the key factor in input capacitor selection is the minimum input voltage, which can be tolerated. The minimum input capacitor (CIN, MIN) can be calculated by the following equation CIN, MIN = 1.3 x IOUT x D x TS VIN - VIN, MIN where VIN, MIN is the tolerable input voltage, VIN, MIN=VIN–VOUT, MAX. The rated voltage of input capacitor should be at least 1.5 times of input voltage. A tantalum or ceramic capacitor can be used as an input capacitor. The advantages of tantalum capacitor are high capacitance and low ESR. The - 11 - October 2007, V1.00 MBI6650 1.2A DC/DC Converter advantages of ceramic capacitor are high frequency characteristic, small size and low cost. Users can choice an appropriate one for applications. Output Capacitor Selection (Optional) A capacitor paralleled with cascaded LED can reduce the LED ripple current and allow the use of smaller inductance. PCB Layout Consideration To enhance the efficiency and stabilize the system, careful considerations of PCB layout is important. There are several factors to be considered. 1. Keep a complete ground area is helpful to eliminate the switching noise. 2. Keep the IC’s GND pin and the ground leads of input and output filter capacitors less than 5mm. 3. Maximize output power efficiency and minimize output ripple voltage, use a ground plane and solder the IC’s GND pin directly to the ground plane. 4. Stabilize the system, the heat sink of the MBI6650 is recommended to connect to ground plane directly. 5. Enhance the heat dissipation, the area of ground plane, which IC’s heat sink is soldered on, should be as large as possible. 6. The input capacitor should be placed to IC’s VIN pin as close as possible. 7. The area, which is comprised by IC’s SW pin, schottky diode and inductor, should be wide and short. 8. The path, which flows large current, should be wide and short to eliminate the parasite element. 9. When SW is on/off, the direction of power loop should keep the same way to enhance the efficiency. The sketch is shown as Figure 38. LED1 LEDn L1 Rsen D1 VIN + - + CIN SW SW --> ON SW --> OFF Figure 38. Power loop of MBI6650 PCB Layout Figure 39 is the recommended layout diagram of the MBI6650. Top layer Bottom layer Figure 39. The layout diagram of the MBI6650 Top-Over layer - 12 - Bottom-Over layer October 2007, V1.00 MBI6650 1.2A DC/DC Converter Package Power Dissipation (PD) The maximum power dissipation, PD(max)=(Tj–Ta)/Rth(j-a), decreases as the ambient temperature increases. MBI6650 Maximum Heat Dissipation at Various Ambient Temperature Power Dissipation (W) 4.0 3.5 3.0 PSD Type: Rth=32.9°C/W 2.5 2.0 Safe Operation Area 1.5 1.0 0.5 0.0 0 20 40 60 80 100 Ambient Temperature (°C) - 13 - October 2007, V1.00 MBI6650 1.2A DC/DC Converter Outline Drawing MBI6650PSD Outline Drawing Note: The unit for the outline drawing is mm. Product Top Mark Information The first row of printing Part number ID number The second row of printing MBIXXXX ○ Digits or MBIXXXX ○ ○ Production Code Package Code Product No. ○ Manufacture Code Device Version Code Process Code G: Green and Pb-free Product Revision History Datasheet version V1.00 Device Version Code A Product Ordering Information Part Number MBI6650PSD Production Code A B “Pb-free” Package Type Weight (g) TO-252-5L 0.3142g - 14 - October 2007, V1.00 MBI6650 1.2A DC/DC Converter Disclaimer Macroblock reserves the right to make changes, corrections, modifications, and improvements to their products and documents or discontinue any product or service without notice. Customers are advised to consult their sales representative for the latest product information before ordering. All products are sold subject to the terms and conditions supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. Macroblock’s products are not designed to be used as components in device intended to support or sustain life or in military applications. Use of Macroblock’s products in components intended for surgical implant into the body, or other applications in which failure of Macroblock’s products could create a situation where personal death or injury may occur, is not authorized without the express written approval of the Managing Director of Macroblock. Macroblock will not be held liable for any damages or claims resulting from the use of its products in medical and military applications. All text, images, logos and information contained on this document is the intellectual property of Macroblock. Unauthorized reproduction, duplication, extraction, use or disclosure of the above mentioned intellectual property will be deemed as infringement. - 15 - October 2007, V1.00