High Efficiency, Constant Current White-LED Driver Feature Voltag

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High Efficiency, Constant Current White-LED Driver Feature Voltag

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AT1313
High Efficiency, Constant Current White-LED Driver Feature
Voltage:2.5V~5.5V Operating Frequency: 1.4MHz Output Voltage: Current <1µA Output Over-voltage protection Dimming Control. Cycle-by Cycle Current-limiting. Soft-Start Function. Reference Voltage SOT-26 Package
AT1313 step-up converter drives white LEDs with constant current provide backlight cell phones, PDAs, other hand-held devices. features allowing series connection white LEDs that currents identical uniform brightness. enable input pulsed repeatedly adjust LED's brightness. fast current-mode control allows smaller capacitor inductor. Fault condition protection uses cycle-by-cycle current limiting sense maximum inductor current, thermal protection over-voltage protection. Also included soft-start eliminates inrush current during start-up. 0.2V reference voltage minimized power loss across current-setting resistor. AT1313 available 6-pin SOT-26 packages.
Application
Module Compact Back Light Module Constant Current Source
Block Diagram
ON/OFF Control Logic Dimming Control VREF Control Logic Overvoltage Protection VREF 0.2V 1.23V Soft-Start
Current Limit 1.2A
Aimtron reserves right without notice change this circuitry specifications.
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver Configuration
Ordering Information
Part number AT1313X_GRE
Package SOT-26, Green
Marking 313, Date Code with bottom line
Date Code
*For more marking information, contact sales representative directly
Symbol Description Step-up Regulator N-MOS Drain. Place output diode inductor. Ground Step-Up Regulator Feedback Input. Connect sense resistor from ground. Enable Dimming Control Input. brightness shutdown controlled voltage Driving longer than shutdown Over-voltage protection input. Connect output. Power supply.
Absolute Maximum Ratings[note1]
Parameter voltage voltage Switch Current (ILX) Continuous power dissipation (SOT-26 Ta=+25OC) Operating Junction Temperature Range Lead Temperature (Soldering sec) Storage Temperature Package Thermal Resistance (JA) Susceptibility (HBM) Susceptibility (MM) Rated Value -0.3 +6.0 -0.3 -0.3 +6.0 0.35 Unit
Note1:Permanent device damage occur Absolute Maximum Ratings exceeded. Exposure absolute maximum rating conditions extended periods affect device reliability
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver
Recommended Operation Conditions
Parameter Power supply voltage Operating temperature Symbol Min. Values Typ. Max. Unit
Electrical Characteristics
(VIN=2.5V, Ta=+25, unless otherwise noted)
Parameter Operating Range Under Voltage Thershold Switch- Input Current Shutdown Current Feedback Reference Input Bias Current Over-voltage Threshold Over-voltage Hysteresis Leakage Current Output Voltage Line Regulation Switching Frequency Maximum Duty Soft-Start charging time Switching Current Limit Resistance Leakage Current Input Current Input Level Shutdown Delay Cycle Time High Cycle Time
Symbol Test Condition input Voltage UVLO IIN1 IIN3 VOVP IOVP fOSC DMAX ILeakage tCYCL tCYCH falling, 100mV hysteresis Switching FB>0.2V EN=0V =0.2V VOUT Rising EN=0V 2.5V< <6.0V
Min. 0.190 0.05 0.05 0.05
Typ. Max. Units 0.210
VIN=3.0V,duty cycle=80% =2.5V, =800mA =16V, EN=0V EN=5V
Note(1) Note(1)
Note(1): tCYCL tCYCH included rising time falling time signal.
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver Typical Characteristics
Efficiency LED) L:SR0302 D:RB501-40
Efficiency LED) L:SR0302 D:RB501-40
fficien
fficien
Io=100mA, L=22uH Io=100mA, L=10uH Io=100mA,L=6.8uH
Io=100mA, L=22uH Io=100mA, L=10uH Io=100mA,L=6.8uH
Conversion Efficiency L:SR0302 D:RB501-40
4LEDs, L=22uH,Vin=3V
CH1:LX CH3:VOUT Ripple CH4:ILX
Efficiency
3LEDs,L=22uH,Vin=3V
CURRENT(mA)
CH1:EN
CH3:FB
Switching Transient Waveform CH1:EN CH3:FB CH4:IIN
Dimming Control Using
Start-Up Waveform
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver Application Circuit
10uH 3.6V 4.2V 4.7uF MBR140WS
4.7uF
AT1313
Signal
Figure AT1313 Typical Application Circuit with 100mA Output
10uH 4.7uF
MBR140WS
4.7uF
AT1313
0.333 From
Signal
AO3400
Figure AT1313 Typical Application Circuit with 200mA Output
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver Application Circuit
10uH 5.0V 4.7uF
MBR140WS
LED1
LED12
10uF
10uF
AT1313
Signal
Figure AT1313 Innolux Panel Back light unit
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver Function AT1313 high efficiency constant current DC-DC converter which designed primarily module applications. output voltage step-up converter from with external sense resistor. device suits drive series-connected LEDs provides even illumination sourcing same output current through each LED. AT1313 also consists logic shutdown cycle-by-cycle current-limited soft-start functions. Logic control input duty cycle control allows easy adjustment LEDs brightness on/off control. average current proportionable duty-cycle signal. Typical frequency should between 100Hz 1kHz. boost converter operates current-mode constant frequency MHz. Depending duty cycle each switching cycle regulate output voltage. rising edge internal clock control driver logic block sets internal flip-flop when output voltage low, which turns N-MOS. external inductor current ramps linearly, storing energy magnetic filed. Once peak current inductor over trans-conductance output level N-MOS turns off, flip-flop resets, external schottky diode turns This forces current through inductor ramp back down, transferring energy stored magnetic field output capacitor LEDs. reduce external component amount device will built-in internal loop compensation. Enable Control Digital logic provides electrical ON/OFF control power supply. Connecting this ground voltage less than 0.5V sustain level over will completely turn regulator. this state, current drain from input supply less than 1uA, internal reference, error amplifier, comparators, biasing circuitry turn holding time level less than this pin, then device only shutdown driver logic block. Dimming Control Digital logic also provides LEDs brightness control applying signal pin. With this way, LEDs operate with either zero full current average current proportional duty-cycle signal. Typical frequency should between 100Hz 1kHz. Output current given
Where:
200mV RSENSE
TON-PWM time signal TS-PWM cycle time signal dimming control required works simple on/off control. Drive high enable device drive shutdown.
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver
Soft-Start Soft-start allows gradual increase internal current-limit level step-up converter during power-up reduce input surge currents. internal current source charges internal soft-start capacitor, peak N-MOS current limited voltage capacitor. another story, when toggle logic-level transition from high, soft-start function must work enable constant current charging internal capacitor. When soft-start process finished appeared falling edge signal soft-start capacitor must discharged ground level. Cycle-by-Cycle Over-Current Protection AT1313 provides cycle-by-cycle over-current protection. Current limit accomplished using separate dedicated comparator. cycle-by-cycle current limit abbreviates on-time N-MOS event that current flowing N-MOS greater than current limit value. current-limit feature protection against hard short over-current fault output. Over-Voltage Protection VOUT above LEDs disconnected from circuit, similar pull down ground with sense resistor. This will cause N-MOS switch with maximum duty cycle come output over-voltage. This cause voltage exceed maximum voltage rating damage built-in N-MOS. state, OVLO protection circuitry stops internal N-MOS When VOUT falls below 16V, will automatically recover normal operation. Power dissipation consideration AT1312 maximum power dissipation depends thermal resistance package circuit board, temperature difference between junction ambient air, rate airflow. power dissipation device depends operating conditions regulator. step-up converter dissipates power across internal N-MOS controller ramps inductor current. continuous condition, power dissipated internally approximated
Pboost
where
load current. fOSC switching frequency.
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver Applications Information
External components main boost converter designed performing simple calculations. need follow regulation output voltage maximum load current, well maximum minimum input voltages. Begin selecting inductor value. Once know, choose diode capacitors. Boost inductor Inductor selection depends input voltage, output voltage, maximum current switching frequency availability inductor values. following boost circuit equations useful choosing inductor values based application. They allow trading peak current inductor value while allowing consideration component availability cost. peak inductor current given
Lpeak LAVG LAVG
where:
inductor peak-to-peak current ripple decided
MOSFET turn ratio decided
fOSC switching frequency. inductor should chosen able handle this current inductor saturation current rating should greater than IPEAK. Diode selection output diode average current peak current same inductor's peak current voltage rating least times output voltage. Schottky diode recommended should able handle those current. Output Capacitor AT1313 specially compensated stable with capacitors which have worst- case minimum value particular VOUT being set. Output ripple voltage requirements also determine minimum value type capacitors. Output ripple voltage consists components voltage drop caused switching current through output capacitor charging discharging output capacitor:
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver
RIPPLE LPEAK
ceramic capacitors, output ripple dominated charging discharging output capacitor. layout guidelines Careful printed circuit layout extremely important avoid causing parasitical capacitance line inductance. following layout guidelines recommended achieve optimum performance. Please boost converter diode inductor close via. Keep traces short, direct, wide. Please ceramic bypass capacitors near input/output pin. Locate feedback sense resistor close feedback pins possible. ground connections VOUT should close together possible.
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver Small Outline SOT-26
SYMBOL
INCHES 0.035 0.000 0.035 0.010 0.003 0.110 0.102 0.059 0.014 0.037ref 0.075ref 0.057 0.006 0.051 0.020 0.008 0.122 0.118 0.069 0.022
MILLIMETERS 0.90 1.45 0.00 0.15 0.90 1.30 0.25 0.50 0.08 0.20 2.80 3.10 2.60 3.00 1.50 1.75 0.35 0.55 0.95ref 1.90ref
NOTES
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw
AT1313
High Efficiency, Constant Current White-LED Driver
Reflow Profiles
Profile Feature
Sn-Pb Eutectic Assembly Large Body Small Body Pkg. thickness Pkg. thickness <2.5mm Pkg. 2.5mm Pkg. volume 350mm3 volume <350mm 3°C/second max.
Pb-Free Assembly Large Body Small Body Pkg. thickness Pkg. thickness <2.5mm Pkg. 2.5mm Pkg. volume<350mm3 volume 350mm3 3°C/second max.
Average ramp-up rate Preheat -Temperature Min(Tsmin) -Temperature (Tsmax) -Time (min max)(ts) Tsmax -Ramp-up Rate Time maintained above: -Temperature (TL) -Time (tL) Peak Temperature(TP) Time within actual Peak Temperature (tP) Ramp-down Rate Time 25°C Peak Temperature
100°C 150°C 60-120 seconds
150°C 200°C 60-180 seconds 3°C/second max.
183°C 60-150 seconds 225+0/-5°C 10-30 seconds 240+0/-5°C 10-30 seconds
217°C 60-150 seconds 245+0/-5°C 10-30 seconds 250+0/-5°C 20-40 seconds
6°C/second max. minutes max.
6°C/second max. minutes max.
*All temperatures refer topside package, measured package body surface.
No.9, PARK AVENUE Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 10/31/2006 REV:2.0 Email:service@aimtron.com.tw

High Efficiency, Constant Current White-LED Driver Feature Voltag

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