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Features
2 constant-current output channels
Preliminary Datasheet
MBI1802
All-Ways-OnTM High-Power LED Driver
Constant output current invariant to load voltage change Maximum output constant current: 360 mA Thermal protection and report Output current adjustment Schmitt trigger input 5V supply voltage Package type: SOP8 with thermal pad Current Accuracy Between Channels < 3% Between ICs < 6% Conditions IOUT = 40mA ~ 360 mA @ VDS= 0.6V
Product Description
MBI1802 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. With All-Ways-OnTM, MBI1802 easily provides users with a consistent current source in their system design. Users may adjust the output current up to 360 mA through an external resistor, Rext, which gives users flexibility in controlling the light intensity of LEDs. Also, users can precisely adjust LED brightness from 0% to 100% via output control with Pulse Width Modulation. Alternatively, MBI1802 provides one-step current adjustment to make a quarter of the output current via enabling the QUAD pin as "High". Additionally, to ensure the system reliability, MBI1802 is built with TP (Thermal Protection) function and thermal pad. The TP function can protect IC from over temperature (165C) and the thermal pad can enhance the power dissipation. As a result, a large amount of current can be handled safely in one package.
Applications
High-Flux LED Lighting Automotive Interior Lighting
Macroblock, Inc. 2005 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 -1January 2005, V1.00
MBI1802
Typical Application Circuit
VDD VLED
All-Ways-OnTM High-Power LED Driver
1 GND Rext 2 R-EXT 3 QUAD 4 OUT0
VDD 8 OE 7 ERR 6
OUT1 5
Figure 1
Block Diagram
QUAD
OUT0 OUT1
R-EXT
VDD
IO Regulator
Thermal Sensor
2 switches
OE
ERR
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January 2005, V1.00
MBI1802
Pin Configuration
GND R-EXT QUAD OUT0 1 2 3 4
Thermal Pad
All-Ways-OnTM High-Power LED Driver
8 7 6 5
VDD OE ERR OUT1
MBI1802
Terminal Description
Pin No. 1 Pin Name GND Function Ground terminal for control logic and current sink Terminal used to connect an external resistor(Rext) for setting up output current for all output channels Set all the output current to 25% of the pre-set current when QUAD is high.
2
R-EXT
3 4, 5
QUAD
OUT0 ~ OUT1 ERR
Constant current output terminals Thermal error flag, when junction temperature is over 165C, ERR is going to high.* Output enable terminal When OE (active) low, the output drivers are enabled; when OE high, all output drivers are turned OFF (blanked). 5V supply voltage terminal Power dissipation terminals with ground connection*
6
7
OE
8 -
VDD Thermal Pad
*To eliminate the noise influence, the thermal pad should be connected to GND. In addition, desired thermal conductivity will be better if the conduction area on PCB connecting to the thermal pad is large enough.
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January 2005, V1.00
MBI1802
Maximum Ratings
Characteristic
All-Ways-OnTM High-Power LED Driver
Symbol
Rating
Unit
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
VDD VIN IOUT VDS IGND PD
0~7.0 -0.4~VDD + 0.4 360* -0.5~+17.0 720 0.8 33.39**
V V mA V mA W
Rth(j-a) 125 Topr Tstg -40~+85 -55~+150
C/W
C C
*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 MBI1802 within the defined temperature limits (Rth(j-a)= 33.39C/W).
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January 2005, V1.00
MBI1802
Electrical Characteristics
Characteristic Symbol
All-Ways-OnTM High-Power LED Driver
Condition
Min.
Typ.
Max.
Unit
Supply Voltage Output Voltage Output Current Input Voltage "H" level "L" level
VDD VDS IOUT VIH VIL IOH IOUT1 dIOUT1 IOUT2 dIOUT2 %/dVDS %/dVDD RIN(up) Tj IDD(off) 1 "OFF" IDD(off) 2 IDD(off) 3 "ON" IDD(on) 1 IDD(on) 2
OUT0 ~ OUT1
-
4.5 40 0.7*VDD GND Rext= 720 Rext= 720 Rext= 1440 Rext= 1440 250 Off Off Off On On -
5.0 204 1 102 1 0.1 1 500 165 1.6 4.5 3.2 4.5 3.2
5.5 17.0 360 VDD 0.3*VDD 0.5 3 3 800 3.6 7.5 6.2 7.5 6.2
V V mA V V A mA % mA % %/V %/V K C
DC Test Circuit Ta= -40~85C Ta= -40~85C VOH= 17.0V VDS= 0.6V IOL= 204mA VDS= 0.6V VDS= 0.5V IOL= 102mA VDS= 0.5V
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 Thermal Protection Temperature
VDS within 1.0V and 3.0V VDD within 4.5V and 5.5V OE Junction Temperature Rext=Open, Rext=720 , Rext=1440 , Rext=720 , Rext=1440 ,
OUT0 ~ OUT1 = OUT0 ~ OUT1 =
Supply Current
OUT0 ~ OUT1 =
OUT0 ~ OUT1 =
mA
OUT0 ~ OUT1 =
Test Circuit for Electrical Characteristics
VDD IDD VDD Function Generator
Logic input waveform VIH VIL
IOUT OUT0
OE QUAD R-EXT IR-EXT
OUT1 GND VDS CL VL
Figure 2
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January 2005, V1.00
MBI1802
Switching Characteristics
Characteristic
All-Ways-OnTM High-Power LED Driver
Symbol Condition Min. Typ. Max. Unit
Propagation Delay Time ("L" to "H") Propagation Delay Time ("H" to "L") Pulse Width
OE - OUTn OE - OUTn
OE
tpLH tpHL tw(OE) tor tof
Output Rise Time of Vout (turn off) Output Fall Time of Vout (turn on)
VDD= 5.0 V VDS= 1-1.6V VIH= VDD VIL= GND Rext= 600 VL= 4.0 V RL= 10 CL= 10 pF
1 1 10 1 1
2 2 1.7 1.7
3 3 3 3
s s s s s
Test Circuit for Switching Characteristics
VDD IDD VDD Function Generator
Logic input waveform VIH VIL
IOUT OUT0
OE QUAD R-EXT IR-EXT
OUT1 GND CL VDS
RL
VL
Figure 3
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January 2005, V1.00
MBI1802
Application Information Constant Current
All-Ways-OnTM High-Power LED Driver
In LED lighting applications, MBI1802 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 (mA) 400 350 300 250 200 150 100 50 0
0.0 0.2
MBI1802 I OUT vs. VOUT for various Rext
Rext= 2907 ohm Rext= 1455 ohm Rext= 984 ohm Rext= 732 ohm Rext= 586 ohm Rext= 491 ohm Rext= 422 ohm
0.4
0.6
VOUT (V)
0.8
1.0
1.2
1.4
Figure 4
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January 2005, V1.00
MBI1802
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.
MBI1802 IOUT vs. Rext
IOUT(mA) 400 350 300 250 200 150 100 50 0 0 500 1000
1500
2000
2500
3000
3500
Rext(ohm)
Figure 5
Also, the output current can be calculated from the equation: VR-EXT = 1.28VRext= (VR-EXT / IOUT) x 115= (1.28V / IOUT) x 115 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 102 mA at 1440 and 204 mA at 720.
TP Function (Thermal Protection)
When the junction temperature exceeds the limit (165C), TP starts to function and turn off the output current and the thermal error flag, ERR, goes high simultaneously. As soon as the temperature is below 165C, the output current will be on again. The switching runs at a high frequency, so the blinking is imperceptible. However, the DC output current is limited and thus the driver is protected from overheat.
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January 2005, V1.00
MBI1802
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) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 25 50 Ambient Temperature (C)
Figure 6 The maximum allowable package power dissipation is determined as PD(max) = (Tj - Ta) / Rth(j-a). When 2 output channels are turned on simultaneously, the actual package power dissipation is PD(act) = (IDD x VDD) + (IOUT x Duty x VDS x 2). 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 / 2, where Tj = 125C; Duty= tON / T; tON: the time of LEDs turning on; T: OE signal period
tON
SOP-8(CD) Type: Rth(j-a)= 125(C/W)*
Safe Operation Area
75
100
OE
T
*Note1: The thermal resistor Rth(j-a) =125 C/W is based on the following structure.
Copper foil
The PCB area L2xW2 is 4 times to the IC's area L1xW1.
L2 L1
The thickness of the PCB is 1.6mm, copper foil 1 Oz. The thermal pad on the
W1 W2
IC's bottom has to be mounted on the copper foil.
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January 2005, V1.00
MBI1802
Load Supply Voltage (VLED)
All-Ways-OnTM High-Power LED Driver
MBI1802 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 VDS
VDrop VLED VF VDS
MBI1802
MBI1802
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January 2005, V1.00
MBI1802
Outline Drawing
All-Ways-OnTM High-Power LED Driver
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January 2005, V1.00

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