AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER NEW PRODUCT Description Pin Assignments The AL9910/A high voltage PWM LED driver-controller provides an efficient solution for offline high brightness LED lamps from rectified line voltages ranging from 85VAC up to 277VAC. The AL9910 drives external MOSFETs at switching frequencies up to 300kHz, with the switching frequency determined by a single resistor. The AL9910 topology creates a constant current through the LEDs providing constant light output. The output current is programmed by one external resistor and is ultimately determined by the external MOSFET chosen and therefore allows many low current LEDs to be driven as well as a few high current LEDs The LED brightness can be varied by both Linear and PWM dimming using the AL9910’s LD and PWM_D pins respectively. The PWM_D input operates with duty ratio of 0-100% and frequency of up to several kHz. The AL9910 can withstand input voltages up to 500V which makes it very resilient to transients at standard mains voltages. As well as standard SO-8 package the AL9910 is available in the thermally enhanced SO-8EP package. (Top View) 8 ROSC VIN 1 CS 2 AL9910 7 LD 6 VDD 5 PWM_D GND 3 GATE 4 SO-8 (Top View) 8 ROSC VIN 1 CS 2 AL9910 7 LD 6 VDD 5 PWM_D GND 3 GATE 4 SO-8EP Features • • • • • • • • • >90% Efficiency Universal rectified 85 to 277VAC input range Input voltage up to 500V Internal voltage regulator removes start-up resistor o 7.5V MOSFET drive – AL9910 o 10V MOSFET drive – AL9910A Tighter current sense tolerance: 5% AL9910-5 Drives LED Lamps with both high and low current LEDs LED brightness control with Linear and PWM dimming Internal Thermal Protection (OTP) SO-8 and SO-8EP in “Green” Molding Compound (No Br, Sb) with Lead Free Finish/ RoHS Compliant (Note 1) Notes: Applications • • • • • LED offline lamps High voltage DC-DC LED Driver Signage and Decorative LED Lighting Back Lighting of Flat Panel Displays General purpose constant current source 1. EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2). All applicable RoHS exemptions applied. Please visit our website at http://www.diodes.com/products/lead_free.html. Typical Application Circuit D1 VAC IN VDD C1 BR1 VIN L1 Q1 AL9910/A LD C3 GATE C2 PWM_D ROSC GND CS RSENSE ROSC AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 1 of 16 www.diodes.com February 2012 © Diodes Incorporated AL99 910/AL L9910A A/AL99 910-5 UNIVERSAL HIGH VOL LTAGE HIGH BRIGHTN NESS LED DRIVER NEW PRODUCT Pin Descriiptions Pin Name SO-8 SO-8 8EP Descriptions s VIN 1 1 Input volttage CS 2 2 Senses LED L string and external MOS SFET switch current GND 3 3 Device ground g Gate 4 4 Drives th he gate of the external e MOSFET switch. PWM_D 5 5 Low Freq quency PWM Dimming D pin, also Enable inpu ut. Internal 200 0kΩ pull-down to t GND VDD 6 6 pply voltage. Internallyy regulated sup • 7.5V nominal for f AL9910 and d AL9910-5 10V nominal fo or AL9910A. • ply up to 1 mA for external cirrcuitry. A sufficcient storage ca apacitor is used d to Can supp provide storage s when the rectified AC C input is near the t zero crossing. LD 7 7 Linear Dimming input. Changes C the current limit thre eshold at current sense comp parator and chan nges the average LED curren nt. ROSC 8 8 Oscillator control. A ressistor connecte ed between thiss pin and groun nd sets the PW WM frequenccy. The devicess can be switch hed into constant off time (PFM) mode by co onnecting the exterrnal oscillator re esistor between ROSC pin and d the gate of th he external MO OSFET. EP PAD N/A EP Exposed d Pad (bottom). Connect to GND G directly un nderneath the package. p Functiona al Block Dia agram AL9910/AL99 910A/AL9910 0-5 Document numberr: DS35103 Rev. 7 - 2 2 of 16 ww ww.diodes.com Febru uary 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Absolute Maximum Ratings (Note 2) Symbol Ratings Unit Maximum input voltage, VIN, to GND -0.5 to +520 V VCS Maximum CS input pin voltage relative to GND -0.3 to +0.45 V VLD Maximum LD input pin voltage relative to GND -0.3 to (VDD +0.3) V Maximum PWM_D input pin voltage relative to GND -0.3 to (VDD +0.3) V Maximum GATE pin voltage relative to GND -0.3 to (VDD +0.3) V 12 V SO-8 (derate 6.3mW/°C above +25°C) 630 mW SO-8EP (derate at 22mW/°C above 25°C) 2200 mW TJ Junction Temperature Range +150 °C TST Storage Temperature Range -65 to +150 °C VIN(MAX) VPWM_D VGATE NEW PRODUCT VDD(MAX) Parameter Maximum VDD pin voltage relative to GND Continuous Power Dissipation (TA = 25°C) ESD HBM Human Body Model ESD Protection (Note 3) 1500 V ESD MM Machine Model ESD Protection (Note 3) 300 V Notes: 2. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. all voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. 3. Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling and transporting these devices Recommended Operating Conditions Symbol VINDC TA VDD Parameter Input DC supply voltage range Ambient temperature range (Note 4) Maximum recommended voltage applied to VDD pin (Note 5) Min Max AL9910 AL9910-5 15.0 500 AL9910A 20.0 500 AL9910_S -40 +85 AL9910_SP -40 +105 AL9910 AL9910-5 10 AL9910A 11 VEN(LO) Pin PWM_D input low voltage 0 1 VEN(HI) Pin PWM_D input high voltage 2.4 VDD Notes: Unit V °C V V 4. Maximum ambient temperature range is limited by allowable power dissipation. The Exposed pad SO-8EP with its lower thermal impedance allows the variants using this package to extend the allowable maximum ambient temperature range. 5. When using the AL9910 in isolated LED lamps an auxiliary winding might be used. AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 3 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Electrical Characteristics (Over recommended operating conditions unless otherwise specified - TA = 25°C) Specifications apply to AL9910, AL9910A and AL9910-5 unless otherwise specified Symbol Parameter Conditions IINSD Shut-down mode supply current NEW PRODUCT VDD Internally regulated voltage VDD current available for external circuitry IDD(ext) VDD under voltage lockout threshold UVLO Pin PWM_D to GND, VIN = VIN(MIN) (Note 6) Typ. Max AL9910 AL9910-5 0.50 1 AL9910A 0.65 1.2 7.0 7.5 8.0 9.5 10 10.5 AL9910 VIN = VIN(MIN)~500V, (Note 6) AL9910-5 lDD(ext) = 0, Gate pin open AL9910A Min VIN = VIN(Min) to 100V (Notes 6 & 7) VDD rising VDD under voltage lockout ∆UVLO hysteresis VDD falling RPWM_D PWM_D pull-down resistance VPWM_D = 5V VCS(HI) Full ambient temperature range (Note 8) 1.0 AL9910 AL9910-5 6.4 6.7 7 AL9910A 8.4 9 9.6 AL9910 AL9910-5 500 AL9910A Current sense threshold voltage AL9910 AL9910A AL9910-5 Unit mA V mA V mV 750 150 200 250 225 250 275 237.5 250 262.5 kΩ mV VGATE(HI) GATE high output voltage IOUT = 10mA VDD -0.3 VDD V VGATE(LO) GATE low output voltage IOUT = -10mA 0 0.3 V ROSC = 1MΩ 20 25 30 ROSC = 226kΩ 80 100 120 fOSC Oscillator frequency Maximum Oscillator PWM Duty Cycle fPWMhf = 25kHz, at GATE, CS to GND. Linear Dimming pin voltage range Full ambient temperature range (Note 8), VIN = 20V tBLANK Current sense blanking interval VCS = 0.45V, VLD = VDD tDELAY Delay from CS trip to GATE lo DMAXhf VLD kHz 100 % 0 - 250 mV 160 250 440 ns 300 ns VIN = 20V, VLD = 0.15, VCS = 0 to 0.22V after TBLANK tRISE GATE output rise time CGATE = 500pF 30 50 ns tFALL GATE output fall time CGATE = 500pF 30 50 ns TSD Thermal shut down 150 TSDH Thermal shut down hysteresis 50 θJA Thermal Resistance Junction-toAmbient θJC Thermal Resistance Junction-toCase Notes: SO-8 (Note 9) 110 SO-8EP (Note 10) 66 SO-8 (Note 9) 22 SO-8EP (Note 10) 9 °C °C/W °C/W 6. VIN(MIN) for the AL9910 is 15V and for the AL9910A it is 20V. 7. Also limited by package power dissipation limit, whichever is lower. 8. Full ambient temperature range for AL9910-5S, AL9910AS and AL9910S is -40 to +85°C; for AL9910-5SP, AL9910ASP and AL9910SP is -40 to +105°C. 9. Device mounted on FR-4 PCB (25mm x 25mm 1oz copper, minimum recommended pad layout on top. For better thermal performance, larger copper pad for heat-sink is needed. 10. Device mounted on FR-4 PCB (51mm x 51mm 2oz copper, minimum recommended pad layout on top layer and thermal vias to bottom layer ground plane. For better thermal performance, larger copper pad for heat-sink is needed. AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 4 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER 460 2.5 440 2.0 420 INPUT CURRENT (µA) CURRENT SENSE THRESHOLD (mV) 3.0 1.5 1.0 0.5 0.0 V IN = 400V 400 V IN = 15V 380 360 340 -0.5 320 -1.0 300 -1.5 -40 280 -40 -15 10 35 60 85 AMBIENT TEMPERATURE (°C) Change in Current Sense Threshold vs. Ambient Temperature 85 SHORT CIR CUIT OU TPUT CURRENT (mA) 450 1.0 CHANGE IN FREQUENCY (%) -15 10 35 60 AMBIENT TEMPERATURE (° C) Input Current vs. Ambient Temperature 1.5 0.5 R OSC = 226kΩ 0.0 -0.5 ROSC = 1M Ω -1.0 -1.5 -2.0 -40 -15 10 35 60 85 AMBIENT TEMPERATURE (°C) Change in Oscillation Frequency vs. Ambient Temperature ILED(NOM) = 180mA 400 350 300 250 200 150 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Short Circuit Output Current vs. Input Voltage 100 ILED = 281mA 90 V IN = 264V TA = 23.5C 80 70 IO UT MAX (%) NEW PRODUCT Typical Characteristics 60 50 40 30 20 10 0 0 50 100 150 200 250 V LD DIMMING CONTROL (mV) I OUT MAX vs. V LD Dimming Control AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 300 5 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Typical Characteristics (cont.) Measured using AL9910EV4 200 95 15 LEDs 14 LEDs 190 18 LEDs EFFICIENCY (%) IOUT MAX (mA) 16 LEDs 170 17 LEDs 160 90 17 LEDs 14 LEDs 16 LEDs 85 15 LEDs 150 18 LEDs 140 85 80 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Output Current vs. Input Voltage 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Efficiency vs. Input Voltage 12 0.95 17 LEDs 18 LEDs 18 LEDs 0.9 POWER (W) 10 POWER FACTOR NEW PRODUCT 180 16 LEDs 0.85 17 LEDs 0.8 16 LEDs 8 15 LEDs 14 LEDs 15 LEDs 6 0.75 14 LEDs 0.7 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Power Factor vs. Input Voltage AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 4 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Input Power Dissipation vs. Input Voltage 6 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information The AL9910 is very versatile and is capable of operating in isolated or non-isolated topologies. It can also be made to operate in continuous as well as discontinuous conduction mode. VIN VIN 7.5/10V LDO OSC VDD VDD NEW PRODUCT ROSC 250mV S R LD O GATE CS OTP PWM_D 100k AL9910/AL9910A RSENSE GND Fig. 1 Functional Block Diagram The AL9910 contains a high voltage LDO (see figure 1) the output of the LDO provides a power rail to the internal circuitry including the gate driver. A UVLO on the output of the LDO prevents incorrect operation at low input voltage to the VIN pin. In a non-isolated Buck LED driver when the gate pin goes high the external power MOSFET Q1 is turned on causing current to flow through the LEDs, inductor (L1) and current sense resistor (RSENSE). When the voltage across RSENSE exceeds the current sense pin threshold the external MOSFET Q1 is turned off. The stored energy in the inductor causes the current to continue to flow through the LEDs via diode D1. The AL9910’s LDO provides all power to the rest of the IC including Gate drive this removes the need for large high power start-up resistors. This means that operate correctly it requires around 0.5mA from the high voltage power rail. The LDO can also be used to supply up to 1mA to external circuits. The AL9910 operates and regulates by limiting the peak current of the external MOSFET; the peak current sense threshold is nominally set at 250mV. The same basic operation is true for isolated topologies, however in these the energy stored in the transformer delivers energy to LEDs during the off-cycle of the external MOSFET. Design Parameters Setting the LED Current In the non-isolated buck converter topology, figure 1, the average LED current is not the peak current divided by 2 - however, there is a certain error due to the difference between the peak and the average current in the inductor. The following equation accounts for this error: 250mV R SENSE = . (ILED + (0.5 * IRIPPLE ))) AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 7 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (cont.) Setting Operating Frequency NEW PRODUCT The AL9910 is capable of operating over a 25 and 300 kHz switching frequency range. The switching frequency is programmed by connecting an external resistor between ROSC pin and ground. The corresponding oscillator period is: + 22 R µs with ROSC in kΩ tOSC = osc 25 The switching frequency is the reciprocal of the oscillator period. Typical values for ROSC vary from 75kΩ to 1MΩ When driving smaller numbers of LEDs, care should be taken to ensure that tON > tBLANK. The simplest way to do this is to reduce/limit the switching frequency by increasing the ROSC value. Reducing the switching frequency will also improve the efficiency. When operating in buck mode the designer must keep in mind that the input voltage must be maintained higher than 2 times the forward voltage drop across the LEDs. This limitation is related to the output current instability that may develop when the AL9910 operates at a duty cycle greater than 0.5. This instability reveals itself as an oscillation of the output current at a subharmonic (SBO) of the switching frequency. The best solution is to adopt the so-called constant off-time operation as shown in Figure 2. The resistor (ROSC) is, connected to ground by default, to set operating frequency. To force the AL9910 to enter constant OFF time mode ROSC is connected to the gate of the external MOSFET. This will decrease the duty cycle from 50% by increasing the total period, tOFF + tON. VIN VDD LD VIN Q1 AL9910/A GATE CS PWM_D ROSC GND ROSC Fig. 2 Constant Off-Time Configuration The oscillator period equation above now defines the AL9910 off time, tOFF. When using this mode the nominal switching frequency is chosen and from the nominal input and output voltages the off-time can be calculated: ⎛ VOUT(nom ) ⎞ ⎟∗ 1 t OFF = ⎜1 − ⎜ VIN(nom ) ⎟⎠ fOSC ⎝ From this the timing resistor, ROSC, can be calculated: R OSC = (t OFF (µs) ∗ 25 ) − 22(kΩ) AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 8 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (cont.) Inductor Selection NEW PRODUCT The non-isolated buck circuit, Figure 1, is usually selected and it has two operation modes: continuous and discontinuous conduction modes. A buck power stage can be designed to operate in continuous mode for load current above a certain level usually 15% to 30% of full load. Usually, the input voltage range, the output voltage and load current are defined by the power stage specification. This leaves the inductor value as the only design parameter to maintain continuous conduction mode. The minimum value of inductor to maintain continuous conduction mode can be determined by the following example. The required inductor value is determined from the desired peak-to-peak LED ripple current in the inductor; typically around 30% of the nominal LED current. (VIN − VLEDs ) × D Where D is duty cycle L= (0.3 × ILED ) × fOSC The next step is determining the total voltage drop across the LED string. For example, when the string consists of 10 High-Brightness LEDs and each diode has a forward voltage drop of 3.0V at its nominal current; the total LED voltage VLEDS is 30V. Dimming The LED brightness can be dimmed either linearly (using the LD pin) or via pulse width modulation (using the PWM-D pin); or a combination of both - depending on the application. Pulling the PWM_D pin to ground will turn off the AL9910. When disabled, the AL9910’s quiescent current is typically 0.5mA (0.65 for AL9910A). Reducing the LD voltage will reduce the LED current but it will not entirely turn off the external power transistor and hence the LED current – this is due to the finite blanking period. Only the PWM_D pin will turn off the power transistor. Linear dimming is accomplished by applying a 45 to 250mV analog signal to the LD pin. This overrides the default 250mV threshold level of the CS pin and reduces the output current. If an input voltage greater than 250mV is applied to the LD then the output current will not change. The LD pin also provides a simple cost effective solution to soft start; by connecting a capacitor to the LD pin down to ground at initial power up the LD pin will be held low causing the sense threshold to be low. As the capacitor charges up the current sense threshold will increase thereby causing the average LED current to increase. PWM dimming is achieved by applying an external PWM signal to the PWM_D pin. The LED current is proportional to the PWM duty cycle and the light output can be adjusted between zero and 100%.. The PWM signal enables and disables the AL9910 - modulating the LED current. The ultimate accuracy of the PWM dimming method is limited only by the minimum gate pulse width, which is a fraction of a percentage of the low frequency duty cycle. PWM dimming of the LED light can be achieved by turning on and off the converter with low frequency 50Hz to 1000Hz TTL logic level signal. With both modes of dimming it is not possible to achieve average brightness levels higher than the one set by the current sense threshold level of the AL9910. If a greater LED current is required then a smaller sense resistor should be used Output Open Circuit Protection The non-isolated buck LED driver topology provides inherent protection against an open circuit condition in the LED string due to the LEDs being connected in series with the inductor. Should the LED string become open circuit then no switching occurs and the circuit can be permanently left in this state with damage to the rest of the circuit. AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 9 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (cont.) AC/DC Off-Line LED Driver The AL9910 is a cost-effective off-line buck LED driver-controller specifically designed for driving LED strings. It is suitable for being used with either rectified AC line or any DC voltage between 15-500V. See figure 3 for typical circuit. LED + NEW PRODUCT D1 VAC IN VDD C1 C2 BR1 LD VIN C3 L1 LED - AL9910/A PWM_D ROSC GND Q1 GATE CS RSENSE ROSC Fig. 3 Typical Application Circuit (without PFC) Buck Design Equations: D= VLEDs VIN t ON = L≥ D fosc ( VIN − VLEDs ) × t ON 0.3 × ILED R SENSE = 0.25 where ILED x 0.3 = IRIPPLE ILED + (0.5 × (ILED × 0.3)) Design Example For an AC line voltage of 120V the nominal rectified input voltage VIN = 120V*1.41 = 169V. From this and the LED chain voltage the duty cycle can be determined: D = VLEDs /VIN = 30/169 = 0.177 From the switching frequency, for example fOSC = 50kHz, the required on-time of the external MOSFET can be calculated: tON = D/fOSC = 3.5 µs The value of the inductor for an LED current of 350mA is determined as follows: L = (VIN - VLEDs) * tON /(0.3 * ILED) = 4.6mH AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 10 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (cont.) Input Bulk Capacitor For Offline lamps an input bulk capacitor is required to ensure that the rectified AC voltage is held above twice the LED string voltage throughout the AC line cycle. The value can be calculated from: CIN ≥ PIN × (1 − D CH ) 2 × VLINE _ MIN × 2fL × ΔVDC _ MAX NEW PRODUCT Where Dch : Capacity charge work period, generally about 0.2~0.25 fL : Input frequency for full range (85~265VRMS) ΔVDC _ MAX Should be set 10~15% of 2 VLINE _ MIN If the capacitor has a 15% voltage ripple then a simplified formula for the minimum value of the bulk input capacitor approximates to: I × VLEDs × 0.06 CMIN = LED VIN2 Power Factor Correction If power factor improvement is required then for the input power less than 25W, a simple passive power factor correction circuit can be added to the AL9910 typical application circuit. Figure 4 shows that passive PFC circuitry (3 current steering diodes and 2 identical capacitors) does not significantly affect the rest of the circuit. Simple passive PFC improves the line current harmonic distortion and achieves a power factor greater than 0.85. Passive PFC LED + C4 C1 D1 VAC IN VDD BR1 LD C2 C3 VIN AL9910/A PWM_D ROSC GND Q1 LED L1 GATE CS RSENSE ROSC Fig. 4 Typical Application Circuit with Passive PFC Each of these identical capacitors should be rated for half of the input voltage and have twice as much capacitance as the calculated CMIN of the buck converter circuit without passive PFC (see above section on bulk capacitor calculation). For further design information please see AN75 from the Diodes website. AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 11 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (cont.) DC-DC Buck LED Driver The design procedure for an ac input buck LED driver outlined in the previous chapters equally applies DC input LED drivers. When driving long LED chains care should be taken not to induce SBO – maximum LED chain voltage should be less half of VIN. So either maximum duty cycle should be kept below 50% or use of constant off-time removes this issue. NEW PRODUCT DC-DC Boost LED Driver Due to the topology of the AL9910 LED driver-controller it is capable of being used in boost configurations – at reduced accuracy. The accuracy can be improved by measuring the LED current with an op amp and use the op amp’s output to drive the LD pin. A Boost LED driver is used when the forward voltage drop of the LED string is higher than the input supply voltage. For example, the Boost topology can be appropriate when input voltage is supplied by a 48V power supply and the LED string consists of twenty HB LEDs, as the case may be for a street light. L1 VDD C1 VIN VIN D1 Q1 AL9910/A PWM_D GATE C2 LD ROSC CS C3 GND ROSC RSENSE Fig. 5 Boost LED Driver In a Boost converter, when the external MOSFET is ON the energy is stored in the inductor which is then delivered to the output when the external MOSFET switches OFF. If the energy stored in the inductor is not fully depleted by the next switching cycle (continuous conduction mode) the DC conversion between input and output voltage is given by: V − VIN V VOUT = IN Î D = OUT VOUT 1− D From the switching frequency, fOSC, the on-time of the MOSFET can be calculated: D t ON = fOSC From this the required inductor value can be determined by: V ∗t L = IN ON 0.3 ∗ ILED The Boost topology LED driver requires an output capacitor to deliver current to the LED string during the time that the external MOSFET is on. In boost LED driver topologies if the LEDs should become open circuit damage may occur to the power switch and so some form of detection should be present to provide Over-voltage detection/protection. AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 12 of 16 www.diodes.com February 2012 © Diodes Incorporated AL99 910/AL L9910A A/AL99 910-5 UNIVERSAL HIGH VOL LTAGE HIGH BRIGHTN NESS LED DRIVER Ordering Information n AL L9910 X XX XX - 13 Varia ant NEW PRODUCT Blank : 7.5V VDD A : 10V 1 VDD Device AL9910-5S-13 3 AL9910-5SP-1 13 AL9910AS-13 AL9910ASP-13 AL9910S-13 AL9910SP-13 Notes: VCS Tolerancce Blank : 10% % -5 : 5% Pa ackage Packing S : SO-8 SP : SO-8EP VCS Tolerrance Pac ckage Code Packaging (Note 10) ±5% % ±5% % ±10% % ±10% % ±10% % ±10% % S SP S S S SP S S SP SO-8 SO-8EP SO-8 SO-8EP SO-8 SO-8EP pe & Reel 13 : 13” Tap 13” Tape and Reel Qua antity Part Numberr Suffix 2500/Tap pe & Reel 2500/Tap pe & Reel 2500/Tap pe & Reel 2500/Tap pe & Reel 2500/Tap pe & Reel 2500/Tap pe & Reel -13 -13 -13 -13 -13 -13 10. Pad d layout as shown on Diodes Inc. sug ggested pad layout document AP0200 01, which can be fo ound on our website e at http p://www.diodes.com m/datasheets/ap02 2001.pdf . Marking In nformation n (1) SO-8 (2) SO-8EP AL9910/AL99 910A/AL9910 0-5 Document numberr: DS35103 Rev. 7 - 2 13 of 16 ww ww.diodes.com Febru uary 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Package Outline Dimensions (All Dimensions in mm) 0.254 (1) Package Type: SO-8 E1 E Gauge Plane Seating Plane A1 NEW PRODUCT L Detail ‘A’ 7°~9° h 45° Detail ‘A’ A2 A A3 b e D SO-8 Dim Min Max A 1.75 A1 0.10 0.20 A2 1.30 1.50 A3 0.15 0.25 b 0.3 0.5 D 4.85 4.95 E 5.90 6.10 E1 3.85 3.95 e 1.27 Typ h 0.35 L 0.62 0.82 0° 8° θ All Dimensions in mm (2) Package Type: SO-8EP Exposed Pad 8 5 E1 1 H 4 F b Bottom View E 9° (All sides) N 7° A e D A1 AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 45° Q C 4° ± 3° Gauge Plane Seating Plane E0 L 14 of 16 www.diodes.com SO-8EP (SOP-8L-EP) Dim Min Max Typ A 1.40 1.50 1.45 A1 0.00 0.13 b 0.30 0.50 0.40 C 0.15 0.25 0.20 D 4.85 4.95 4.90 E 3.80 3.90 3.85 E0 3.85 3.95 3.90 E1 5.90 6.10 6.00 e 1.27 F 2.75 3.35 3.05 H 2.11 2.71 2.41 L 0.62 0.82 0.72 N 0.35 Q 0.60 0.70 0.65 All Dimensions in mm February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Suggested Pad Layout (1) Package Type: SO-8 NEW PRODUCT X C1 C2 Dimensions X Y C1 C2 Value (in mm) 0.60 1.55 5.4 1.27 Dimensions X Y X1 Y1 C1 C2 Value (in mm) 0.60 1.55 3.30 2.66 5.4 1.27 Y (2) Package Type: SO-8EP X Exposed Pad X1 C1 Y1 Y C2 AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 15 of 16 www.diodes.com February 2012 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). NEW PRODUCT Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated website, harmless against all damages. Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel. Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings noted herein may also be covered by one or more United States, international or foreign trademarks. LIFE SUPPORT Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein: A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems. Copyright © 2012, Diodes Incorporated www.diodes.com AL9910/AL9910A/AL9910-5 Document number: DS35103 Rev. 7 - 2 16 of 16 www.diodes.com February 2012 © Diodes Incorporated