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Macroblock
Features
1.2A Constant Output Current
Preliminary Datasheet
MBI6650
1.2A DC/DC Converter
Surface Mount Device
93% Efficiency @ input voltage 13V, 350mA, 3-LED 9~36V Input Voltage Range Hysteretic PFM Improves Efficiency at Light Loads Settable Output Current Integrated Power Switch Full Protection: Thermal/UVLO/Soft Start/LED Open-/Short- Circuit 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 (140C). Also, the thermal pad enhances the power dissipation. As a result, a large amount of current can be handled safely in one package.
Applications
Signage and Decorative LED Lighting Automotive LED Lighting High Power LED Lighting 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: info@mblock.com.tw -1October 2007, V1.00
MBI6650
Typical Application Circuit
1.2A DC/DC Converter
RSEN
+ VSEN -
IOUT
+
+
VIN CIN 10uF/50V
+
VIN DIM
SEN MBI6650 GND SW
D1 L1 47uH
COUT
VOUT
-
10uF/50V
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
Comp
SEN
Thermal Shutdown Vref DIM Digital Comp
SW Driver
GND
Figure 2 -2October 2007, V1.00
MBI6650
Pin Configuration
1.2A DC/DC Converter
Pin Description
Pin Name GND SW DIM SEN VIN Thermal Pad Function Ground terminal for control logic and current sink Switch output terminal Dimming control terminal Output current sense terminal Supply voltage terminal 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 Supply Voltage Output Current Sustaining Voltage at SW pin GND Terminal Current Power Dissipation (On 4 Layer PCB, Ta=25C)* Thermal Resistance (By simulation, on 4 Layer PCB) Empirical Thermal Resistance (On 4 Layer PCB, Ta=25C)* Operating Junction Temperature Operating Temperature Storage Temperature Tj,max Topr Tstg PSD Type Rth(j-a) 50.54 125 -40~+85 -55~+150 C C C Symbol VIN IOUT VSW IGND PD Rating 0~40 1.2 -0.5~45 1.2 3.80 32.9 C/W Unit V A V A W
*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. -3October 2007, V1.00
MBI6650
Electrical Characteristics
1.2A DC/DC Converter
(Test condition: VIN=12V, L1=47H, CIN=COUT=10F, TA=25C; 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 150mAIOUT750mA, 5 10 % Output Current Accuracy dIOUT/IOUT 5 10 75mAIOUT1200mA, SW Dropout Voltage VSW IOUT=1.2A 0.3 0.6 V 9VVIN36V, VOUT=3.6V, Line Regulation %/VIN 0.30 0.37 %/V IOUT=350mA VIN=24V, IOUT=350mA, 0.24 1.38 3.6VVOUT18V VIN=24V, IOUT=700mA, %/V Load Regulation %/V 0.24 1.50 3.6VVOUT18V VIN=24V, IOUT=1200mA, 0.24 1.80 3.6VVOUT18V 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 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=-40~85C 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 s Current DutyDIM=50% VOUT=3.6V, IOUT=350mA, fDIM=1kHz, 160 s Fall Time of Output Current tf DutyDIM=50% *Refer to Product Top-Mark Information.
Test Circuit for Electrical Characteristics
Electronic Load
D1 SEN RSEN VIN CIN MBI6650 VIN GND DIM VIH VIL SW
VSW
COUT L1
VIN
SEN MBI6650 VIN GND
SW DIM
(a) Figure 3
(b)
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MBI6650
Typical Performance Characteristics
1.2A DC/DC Converter
Please refer to Typical Application Circuit, VIN=12V, L1=47uH, CIN=COUT=10uF, TA=25C, 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
Efficiency (%) 100
1-LED 2-LED 3-LED 4-LED 5-LED
95 Efficiency (%) 90 85 80 75 70 9 12 15 18 21 24 Input Voltage (V) 27 30 33 36
95 90 85 80 75 70 9 12 15 18 21 24 27 30 33 36 Input Voltage (V) 1-LED 2-LED 3-LED 4-LED 5-LED
Figure 4. Efficiency vs. VIN @ 350mA, L1=47uH
95 Efficiency (%) 90 85 80 75 70 65 60 9 12 15 18 21 24 27 30 33 36 Input Voltage (V)
Figure 5. Efficiency vs. VIN @ 700mA, L1=47uH
95 90 Efficiency (%) 1-LED 2-LED 3-LED 4-LED 5-LED 85 80 75 70 65 60 9 12 15 18 21 24 Input Voltage (V) 27 30 33 36 1-LED 2-LED 3-LED 4-LED 5-LED
Figure 6. Efficiency vs. VIN @ 1000mA, L1=47uH
Figure 7. Efficiency vs. VIN @ 1200mA, L1=47uH
2. Line Regulation
380 Output Current (mA) Output Current (mA) 375 370 365 360 355 350 345 340 9 12 15 18 21 24 Input Voltage (V) 27 30 33 36 1-LED 2-LED 3-LED 4-LED 5-LED 750 740 730 720 710 700 690 680 670 9 12 15 18 21 24 27 30 33 36 Input Voltage (V) 1-LED 2-LED 3-LED 4-LED 5-LED
Figure 8. Line regulation @ 350mA, L1=47uH
1150 Output Current (mA) 1100 1050 1000 950 9 12 15 18 21 24 Input Voltage (V) 27 30 33 36 1-LED 2-LED 3-LED 4-LED 5-LED
Figure 9. Line regulation @ 700mA, L1=47uH
1450 Output Current (mA) 1400 1350 1300 1250 1200 1150 1100 9 12 15 18 21 24 Input Voltage (V) 27 30 33 36 1-LED 2-LED 3-LED 4-LED 5-LED
Figure 10. Line regulation @ 1000mA, L1=47uH
Figure 11. Line regulation @ 1200mA, L1=47uH
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MBI6650
3. Load Regulation
360 350 340 330 320 310 1 2 3 LED (#) 4 5
Vin=12V Vin=24V Vin=36V
1.2A DC/DC Converter
705 700 695 690 685 680 675 670 665 1 2 3 LED (#) 4 5
Output Current (mA)
Output Current (mA)
Vin=12V Vin=24V Vin=36V
Figure 12. Load regulation @ 350mA, L1=47uH
1020 Output Current (mA) 980 960 940 920 900 880 1 2 3 LED (#) 4 5
Vin=12V Vin=24V Vin=36V
Figure 13. Load regulation @ 700mA, L1=47uH
1250 Output Current (mA) 1200 1150 1100 1050 1000 950 1 2 3 LED (#) 4 5
Vin=12V Vin=24V Vin=36V
1000
Figure 14. Load regulation @ 1000mA, L1=47uH
Figure 15. Load regulation @ 1200mA, L1=47uH
4. Switching Frequency
350 300 250 200 150 100 50 0 9 12 15 18 21 24 27 30 33 36 Input Voltage (V) 600 Iout=350mA Iout=700mA Iout=1000mA Iout=1200mA F requenc y (k H z ) 500 400 300 200 100 0 9 12 15 18 21 24 27 30 33 36 Input Voltage (V) Iout=350mA Iout=700mA Iout=1000mA Iout=1200mA
Figure 16. Switching frequency @ 1-LED, L1=47uH
700 600 500 400 300 200 100 0 9 12 15 18 21 24 27 30 33 36 Input Voltage (V)
F requenc y (k H z )
Figure 17. Switching frequency @ 2-LED, L1=47uH
800 F requenc y (k H z ) Iout=350mA Iout=700mA Iout=1000mA Iout=1200mA 600 400 200 0 15 18 21 24 27 30 33 36 Input Voltage (V) Iout=350mA Iout=700mA Iout=1000mA Iout=1200mA
Figure 18. Switching frequency @ 3-LED, L1=47uH
800 F requenc y (k H z )
F requenc y (k H z )
Figure 19. Switching frequency @ 4-LED, L1=47uH
360 350 S it h gFe u n y( H w c in r q e c k z
VIN=12V, Iout=350mA
600 400 200 0 18 21 24 27 Input Voltage (V) 30 33 36
Iout=350mA Iout=700mA Iout=1000mA Iout=1200mA
340 330 320 310 300 290 -40 -15 10 35 Temperature () 60 85
Figure 20. Switching frequency @ 5-LED, L1=47uH
Figure 21. Switching frequency vs. temperature
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MBI6650
5. Miscellaneous
400 Output Current (mA)
1.2A DC/DC Converter
40 Output Current (mA) 35 30 25 20 15 10 5 0
0 10 20 30 40 50 60 Duty Cycle (%) 70 80 90 100
fDIM=100Hz fDIM=300Hz fDIM=500Hz fDIM=700Hz fDIM=1000Hz
fDIM=100Hz fDIM=300Hz fDIM=500Hz fDIM=700Hz fDIM=1000Hz
350 300 250 200 150 100 50 0
0
1
2
3
4 5 6 Duty Cycle (%)
7
8
9
10
Figure 22. Output current vs. DIM duty cycle @ 1-LED, IOUT=350mA
0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 9 12 15 18 21 24 27 30 33 36 Input Voltage (V)
Figure 23. Output current vs. DIM duty cycle @ 1-LED, IOUT=350mA
0.90 Quiescent Current (mA) 0.85 0.80 0.75 0.70 0.65 0.60 9 12 15 18 21 24 Input Voltage (V) 27 30 33 36
Figure 24. Rds (on) vs. VIN
0.90 S u o n C rre t (m ) h td w u n A 0.85 0.80 0.75 0.70 0.65 0.60 9 12 15 18 21 24 27 Input Voltage (V) 30 33 36
R s (o ) ( dn)
Figure 25. Quiescent current vs. VIN
365 360 Ot u C r e t ( A up t ur n m ) 355 350 345 340 335 -40 -15 10 35 Temperature () 60 85
VIN=12V, Iout=350mA
Figure 26. Shutdown current vs. VIN
0.325 0.32 0.315 0.31 VE ( ) SNV 0.305 0.3 0.295 0.29 0.285 0.28 0.275 -40 -15 10 35 Temperature () 60 85
Figure 27. Output current vs. temperature
VIN=12V, Iout=350mA
Figure 28. VSEN vs. temperature
VIN
VSW 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
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October 2007, V1.00
MBI6650
VIN VSW
1.2A DC/DC Converter
VIN VOUT (Attenuation Ratio: 1/20)
VOUT (Attenuation Ratio: 1/20) IL
VSW
IL
Figure 31. Open-circuit protection waveform @ IOUT=350mA
Figure 32. Short -circuit protection waveform @IOUT=350mA
SW DIM
SW IOUT DIM
IOUT
Figure 34. Fall time of output current @ 1-LED, IOUT=350mA, tr=160s
Figure 33. Rise time of output current @ 1-LED, IOUT=350mA, tr=140s
SW
VIN VSW
DIM VOUT (Attenuation Ratio: 1/20) IOUT IOUT
Figure 35. Dimming waveform @ 1-LED, IOUT=350mA, fDIM=100Hz, DutyDIM=10%
Figure 36. Thermal protection
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MBI6650
Application Information
1.2A DC/DC Converter
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 0.28. 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 0.33.
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.
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October 2007, V1.00
MBI6650
RSEN VIN
1.2A DC/DC Converter
SEN
Schottky Diode Equivalent Circuit MBI6650 VF,D1 Rs VF,LED SW DCR Inductor Equivalent Circuit LED Equivalent Circuit
Rds(on)
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.
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October 2007, V1.00
MBI6650
TP Function (Thermal Protection)
1.2A DC/DC Converter
When the junction temperature exceeds the threshold, TX (140C), TP function turns off the output current. Thus, the junction temperature starts to decrease. As soon as the temperature is below 140C, 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 0.8 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
appropriate one for applications.
1.2A DC/DC Converter
advantages of ceramic capacitor are high frequency characteristic, small size and low cost. Users can choice an
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 Rsen LEDn L1
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
Bottom-Over layer October 2007, V1.00
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MBI6650
Package Power Dissipation (PD)
1.2A DC/DC Converter
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 2.5 2.0 1.5 1.0 0.5 0.0 0 20 40 60 80 100 Ambient Temperature (C)
PSD Type: Rth=32.9C/W
Safe Operation Area
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October 2007, V1.00
MBI6650
Outline Drawing
1.2A DC/DC Converter
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 MBIXXXX
or Digits
The second row of printing
MBIXXXX
Production Code
Manufacture Code Device Version Code
Product No.
Package 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 TO-252-5L Weight (g) 0.3142g
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October 2007, V1.00
MBI6650
Disclaimer
1.2A DC/DC Converter
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.
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October 2007, V1.00

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