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Macroblock
Features
l l l l 4 constant-current output channels
Preliminary Datasheet
MBI1804
All-Ways-OnTM High-Power LED Driver
Constant output current invariant to load voltage change Maximum output constant current: 360 mA Excellent output current accuracy: between channels: <3% (max.), and between ICs: <6% (max.) CD: SOP8-150-1.27
l l l l l
Output current adjusted through an external resistor Fast response of output current, OE (min.): 10s Schmitt trigger input 5V supply voltage Package type: SOP8 with thermal pad Current Accuracy Between Channels < 3% Between ICs < 6% Conditions IOUT = 40 ~ 240 mA
Product Description
MBI1804 is an instant On/Off LED driver for high power LED applications and exploits PrecisionDriveTM and All-Ways-OnTM technology to enhance its output characteristics. At MBI1804 output stage, four regulated current ports are designed to provide uniform and constant current sinks for driving LEDs within a large range of VF variations.
With All-Ways-OnTM, MBI1804 provides users easily a consistent current source in their system design. Users may adjust the output current from 20 mA up to 360 mA through an external resistor, Rext, which gives users flexibility in controlling the light intensity of LEDs. In addition, users can precisely adjust LED brightness from 0% to 100% via output control with Pulse Width Modulation. MBI1804 also guarantees LED can be cascaded to maximum 17V at the output ports.
Additionally, to ensure the system reliability, MBI1804 is provided in the SOP8 with thermal pad for dramatically increased power dissipation capability. As a result, a large amount of current can be handled safely in one package.
(c)Macroblock, Inc. 2004 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 -1November 2004, V1.00
MBI1804
Applications
l l l l l High-Flux LED Lighting Automotive Interior Lighting LCD Backlight Photocopier Scanner
All-Ways-OnTM High-Power LED Driver
Typical Application Circuit
VDD 1 R-EXT 2 VLED
GND R-EXT OUT0 OUT1
VDD 8
OE
OE 7 OUT3 6 OUT2 5
3
4
Figure 1
Block Diagram
OUT0 OUT1 OUT2 OUT3
R-EXT
VDD
IO Regulator
4 switches
OE
Terminal Description
Pin No. 1 3, 4, 5, 6 Pin Name GND OUT0 ~ OUT3 Function Ground terminal for control logic and current sink Constant current output terminals Output enable terminal When OE (active) low, the output drivers are enabled; when OE high, all output drivers are turned OFF (blanked). Terminal used to connect an external resistor(Rext) for setting up output current for all output channels 5V supply voltage terminal
Pin Configuration
7
MBI1804
OE
2 8
R-EXT VDD
Maximum Ratings
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MBI1804
Characteristic Supply Voltage Input Voltage Output Current Output Voltage GND Terminal Current Power Dissipation* (On PCB, Ta=25C) Thermal Resistance* (Under good thermal system) Thermal Resistance* (On PCB, Ta=25C) Operating Temperature Storage Temperature SOP8
All-Ways-OnTM High-Power LED Driver
Symbol VDD VIN IOUT VDS IGND PD Rating 0~7.0 -0.4~VDD + 0.4 360* -0.5~+17.0 1440 0.8 33.39** Rth(j-a) 125 Topr Tstg -40~+85 -55~+150 C C C/W Unit V V mA V mA W
*Users must notice that the power dissipation (almost equaling to IOUT x VDS) should be within the Safe Operation Area shown in Figure 6. ** Good thermal system design can ensure that the heat management of the total system (storage temperature and operating temperature) maintains MBI1804 within the defined temperature limits (Rth(j-a)= 33.39C/W).
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MBI1804
Electrical Characteristics
Characteristic Supply Voltage Output Voltage Output Current Input Voltage "H" level "L" level Symbol VDD VDS IOUT VIH VIL IOH IOUT1 dIOUT1 IOUT2 dIOUT2 %/dVDS %/dVDD RIN(up) IDD(off) 1 "OFF" Supply Current "ON" IDD(off) 2 IDD(off) 3 IDD(on) 1 IDD(on) 2
All-Ways-OnTM High-Power LED Driver
Condition OUT0 ~ OUT3 DC Test Circuit Ta= -40~85C Ta= -40~85C VOH= 17.0V VDS= 0.6V IOL= 105mA VDS= 0.6V VDS= 0.8V IOL= 210mA VDS= 0.8V Rext= 720 Rext= 720 Rext= 360 Rext= 360
Min. 4.5 20 0.7*VDD GND 250 Off Off Off On On -
Typ. 5.0 105 1 210 1 0.1 1 500 6 6 6 9 10
Max. 5.5 17.0 360 VDD 0.3*VDD 0.5 3 3 800 8 8 8 11 12
Unit V V mA V V A mA % mA % %/V %/V K
Output Leakage Current Output Current 1 Current Skew Output Current 2 Current Skew Output Current vs. Output Voltage Regulation Output Current vs. Supply Voltage Regulation Pull-up Resistor
VDS within 1.0V and 3.0V VDD within 4.5V and 5.5V OE Rext=Open, Rext=720 , Rext=360 , Rext=720 , Rext=360 ,
OUT0 ~ OUT3 = OUT0 ~ OUT3 = OUT0 ~ OUT3 = OUT0 ~ OUT3 = OUT0 ~ OUT3 =
mA
Test Circuit for Electrical Characteristics
Figure 2
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MBI1804
Switching Characteristics
Characteristic Propagation Delay Time ("L" to "H") Propagation Delay Time ("H" to "L") Pulse Width OE - OUTn OE - OUTn OE
All-Ways-OnTM High-Power LED Driver
Symbol tpLH tpHL tw(OE) tor tof
Condition VDD= 5.0 V VDS= 1-1.5V VIH= VDD VIL= GND Rext= 300 VL= 4.0 V RL= 10 CL= 10 pF
Min. 1 1 10 1 1
Typ. 2 2 1.7 1.7
Max. 3 3 3 3
Unit s s s s s
Output Rise Time of Vout (turn off) Output Fall Time of Vout (turn on)
Test Circuit for Switching Characteristics
Figure 3
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MBI1804
Application Information Constant Current
All-Ways-OnTM High-Power LED Driver
In LED lighting applications, MBI1804 provides nearly no variations in current from channel to channel and from IC to IC. This can be achieved by: 1) The maximum current variation between channels is less than 3%, and that between ICs is less than 6%. 2) In addition, the current characteristic of output stage is flat and users can refer to the figure as shown below. The output current can be kept constant regardless of the variations of LED forward voltages (VF). This performs as a perfection of load regulation. IOUT vs. VDS @ various Rext
400.00 350.00 IOUT(mA) 300.00 250.00 200.00 150.00 100.00 50.00 0.00 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
Rext= 198 Rext= 301 Rext= 361 Rext= 451 Rext= 720 Rext= 1806
VDS (V)
Figure 4
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November 2004, V1.00.
MBI1804
Adjusting Output Current
All-Ways-OnTM High-Power LED Driver
The output current of each channel (IOUT) is set by an external resistor, Rext. The relationship between IOUT and Rext is shown in the following figure.
Relationship between IOUT and Rext
400.00 350.00 300.00
IOUT (mA)
250.00 200.00 150.00 100.00 50.00 0.00 0 500 1000 1500 2000
VDS = 1.0V
Rext ()
Figure 5
Also, the output current can be calculated from the equation: VR-EXT = 1.26VIOUT = (VR-EXT / Rext ) x 60= (1.26V / Rext ) x 60 where Rext is the resistance of the external resistor connected to R-EXT terminal and VR-EXT is the voltage of R-EXT terminal. The magnitude of current (as a function of Rext) is around 210 mA at 360 and 105 mA at 720.
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November 2004, V1.00.
MBI1804
All-Ways-OnTM High-Power LED Driver
Package Power Dissipation (PD)
The maximum power dissipation, PD(max) = (Tj - Ta) / Rth(j-a), decreases as the ambient temperature increases.
Max. Power Dissipation at Various Ambient Temperature
0.9 0.8
Power Dissipation (W)
SOP-8(CD) Type: Rth(j-a)= 125(C/W)*
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 25 50 75 100
Safe Operation Area
Ambient Temperature (C)
Figure 6 The maximum allowable package power dissipation is determined as PD(max) = (Tj - Ta) / Rth(j-a). When 4 output channels are turned on simultaneously, the actual package power dissipation is PD(act) = (IDD x VDD) + (IOUT x Duty x VDS x 4). Therefore, to keep PD(act) PD(max), the allowable maximum output current as a function of duty cycle is: IOUT = { [ (Tj - Ta) / Rth(j-a) ] - (IDD x VDD) } / VDS / Duty / 4, where Tj = 125C; Duty= tON / T; tON: the time of LEDs turning on; T: OE signal period
*Note1: The thermal resistor Rth(j-a) =125 C/W is based on the following structure.
The PCB area L2xW2 is 4 times to the IC's area L1xW1. The thickness of the PCB is 1.6mm, copper foil 1 OZ. The thermal pad on the IC's bottom has to be mounted on the copper foil.
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November 2004, V1.00.
MBI1804
Load Supply Voltage (VLED)
All-Ways-OnTM High-Power LED Driver
MBI1804 are designed to operate with VDS ranging from 0.4V to 1.0V considering the package power dissipating limits. VDS may be higher enough to make PD(act) > PD(max) when VLED = 5V and VDS = VLED - VF, in which VLED is the load supply voltage. In this case, it is recommended to use the lowest possible supply voltage or to set an external voltage reducer, VDROP. A voltage reducer lets VDS = (VLED -VF) - VDROP. Resistors or Zener diode can be used in the applications as shown in the following figures.
Voltage Supply
Voltage Supply
VLED VF
VDrop
VDrop VLED
VDS
VF
VDS
MBI1804
MBI1804
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MBI1804
Outline Drawing
All-Ways-OnTM High-Power LED Driver
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November 2004, V1.00.

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