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 VIN 1 CS GND 2 Gate 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. VIN 1 CS GND 2 Gate (Top View) 8 Rosc 3 7 6 LD VDD 4 5 PWM_D 8 Rosc 3 7 6 LD VDD 4 5 PWM_D AL9910 SO-8 (Top View) 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. AL9910 SO8-EP 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). 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: DS 35103 Rev. 3 - 2 1 of 15 www.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER NEW PRODUCT Pin Descriptions Pin Name SO-8 SO-8EP VIN 1 1 Input voltage Descriptions CS GND Gate PWM_D 2 3 4 5 2 3 4 5 Senses LED string and external MOSFET switch current Device ground Drives the gate of the external MOSFET switch. Low Frequency PWM Dimming pin, also Enable input. Internal 100kΩ pull-down to GND VDD 6 6 Internally regulated supply voltage. • 7.5V nominal for AL9910 and • 10V nominal for AL9910A. Can supply up to 1 mA for external circuitry. A sufficient storage capacitor is used to provide storage when the rectified AC input is near the zero crossing. LD 7 7 Linear Dimming input. Changes the current limit threshold at current sense comparator and changes the average LED current. ROSC 8 8 Oscillator control. A resistor connected between this pin and ground sets the PWM frequency. The devices can be switched into constant off time (PFM) mode by connecting the external oscillator resistor between ROSC pin and the gate of the external MOSFET. EP PAD N/A EP Exposed Pad (bottom). Connect to GND directly underneath the package. Functional Block Diagram VIN VIN 7.5/10V LDO OSC VDD ROSC VDD 250mV S R LD O GATE CS OTP PWM_D 100k AL9910/AL9910A RSENSE GND AL9910/AL9910A/AL9910-5 Document number: DS 35103 Rev. 3 - 2 2 of 15 www.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Absolute Maximum Ratings (Note 2) Symbol VIN(MAX) VCS VLD VPWM_D VGATE NEW PRODUCT VDD(MAX) Ratings Unit Maximum input voltage, VIN, to GND Parameter -0.5 to +520 V Maximum CS input pin voltage relative to GND -0.3 to 0.45 V 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) SO-8EP (derate at 22mW/°C above 25°C) 630 2200 mW mW Junction Temperature Range +125 °C Storage Temperature Range Maximum VDD pin voltage relative to GND Continuous Power Dissipation (TA = 25°C) TJ TST -65 to 150 °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. 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 3. Recommended Operating Conditions Symbol VINDC TA VDD Parameter AL9910 AL9910A Input DC supply voltage range Ambient temperature range Maximum recommended voltage applied to VDD pin (Note 4) Min Max Unit 15.0 20.0 500 500 V -40 85 °C 10 11 V AL9910 AL9910A VEN(lo) Pin PWM_D input low voltage 0 1 VEN(hi) Pin PWM_D input high voltage 2.4 VDD Notes: V 4. When using the AL9910 in isolated LED lamps an auxiliary winding might be used. AL9910/AL9910A/AL9910-5 Document number: DS 35103 Rev. 3 - 2 3 of 15 www.diodes.com June 2011 © 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) NEW PRODUCT Specifications apply to AL9910, AL9910A and AL9910-5 unless otherwise specified Symbol Parameter Conditions 0.50 1 0.65 1.2 Pin PWM_D to GND, VIN = VIN(Min) (Note 5) VDD Internally regulated voltage VIN = VIN(Min)~500V, (Note 5) lDD(ext)=0, Gate pin open IDD(ext) VDD current available for external circuitry VIN = VIN(Min) to 100V (Note 5 & 6) UVLO VDD under voltage lockout threshold VDD rising ∆UVLO VDD under voltage lockout hysteresis VDD falling Current sense threshold voltage AL9910 7.0 7.5 8.0 AL9910A 9.5 10 10.5 1.0 AL9910 6.4 6.7 7 AL9910A 8.4 9 9.6 AL9910 500 AL9910A 750 VPWM_D = 5V TA = -40°C to +85°C Max AL9910 Shut-down mode supply current VCS(hi) Typ. AL9910A IInsd RPWM_D PWM_D pull-down resistance Min AL9910/A AL9910-5 Unit mA V mA V mV 150 200 250 kΩ 225 237.5 250 250 275 262.5 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 DMAXhf VLD Oscillator frequency Maximum Oscillator PWM Duty Cycle Linear Dimming pin voltage range TA = <85°C, VIN = 20V tBLANK Current sense blanking interval tDELAY Delay from CS trip to GATE lo tRISE fPWMhf = 25kHz, at GATE, CS to GND. VCS = 0.45V, VLD = VDD 250 mV 160 250 440 ns 300 ns 30 50 ns 30 50 ns VIN = 20V, VLD = 0.15, VCS = 0 to 0.22V after TBLANK CGATE = 500pF GATE output fall time CGATE = 500pF TSD Thermal shut down 150 TSDH Thermal shut down hysteresis 50 θJC Thermal Resistance Junction-toCase Notes: % - GATE output rise time Thermal Resistance Junction-toAmbient 100 0 tFALL θJA kHz SO-8 (Note 7) 110 SO-8EP (Note 8) 66 SO-8 (Note 7) 22 SO-8EP (Note 8) 9 °C °C/W °C/W 5. VIN(Min) for the AL9910 is 15V and for the AL9910A it is 20V 6. Also limited by package power dissipation limit, whichever is lower. 7. 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. 8. 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: DS 35103 Rev. 3 - 2 4 of 15 www.diodes.com June 2011 © 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 = 15V 380 360 340 320 -1.0 300 -1.5 -40 280 -40 -15 10 35 60 85 AMBIENT TEMPERATURE (°C) Change in Current Sense Threshold vs. Ambient Temperature -15 10 35 60 AMBIENT TEMPERATURE (° C) 85 Input Current vs. Ambient Temperature 450 SHORT CIR CUIT OU TPUT CURRENT (mA) 1.5 1.0 CHANGE IN FREQUENCY (%) V IN = 400V 400 -0.5 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 IOUT MAX (%) NEW PRODUCT Typical Characteristics 60 50 40 30 20 10 0 0 100 150 200 250 V LD DIMMING CONTROL (mV) I OUT MAX vs. V LD Dimming Control 50 AL9910/AL9910A/AL9910-5 Document number: DS 35103 Rev. 3 - 2 300 5 of 15 www.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Typical Characteristics (Continued) 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: DS 35103 Rev. 3 - 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 15 www.diodes.com June 2011 © 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 NEW PRODUCT OSC ROSC VDD VDD 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: DS 35103 Rev. 3 - 2 7 of 15 www.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (Continued) Setting Operating Frequency 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: tOSC = Rosc + 22 µs 25 with ROSC in kΩ NEW PRODUCT 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 − ⎜ V IN(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: DS 35103 Rev. 3 - 2 8 of 15 www.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (Continued) 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 L= Where D is duty cycle (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 HighBrightness 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: DS 35103 Rev. 3 - 2 9 of 15 www.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (Continued) 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 + D1 VAC IN VDD NEW PRODUCT 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 is determined as follows: L = (VIN - VLEDs) * tON /(0.3 * ILED) = 4.6mH AL9910/AL9910A/AL9910-5 Document number: DS 35103 Rev. 3 - 2 10 of 15 www.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (Continued) 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: NEW PRODUCT CIN ≥ Pin × (1 − D ch ) 2 × VLine _ min × 2fL × ΔVDC _ max 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 VIN 2 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: DS 35103 Rev. 3 - 2 11 of 15 www.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Applications Information (Continued) 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: DS 35103 Rev. 3 - 2 12 of 15 www.diodes.com June 2011 © Diodes Incorporated AL99 910/AL L9910A A/AL99 910-5 UNIVE ERSAL HIG GH VOLTAGE HIGH BRIGHTNE B ESS LED DRIVER Ordering Information n AL9910 X XX - 13 Variant P Package Packing Blank : 7.5V VDD S : SO-8 13 : 13” Ta ape & Reel NEW PRODUCT A : 10V VDD Device VCS tolerrance SP P : SO-8EP Package Code Pac ckaging (Note 7) 13” Tape and Reel Qua antity Part Numberr Suffix AL9910S-13 ±10% % S SO-8 2500/Tap pe & Reel -13 AL9910AS-13 AL9910-5SP-1 13 AL9910SP-13 AL9910ASP-13 ±10% % ±5% % ±10% % ±10% % S SP S S SP S SP SO-8 SO-8EP SO-8EP SO-8EP 2500/Tap pe & Reel 2500/Tap pe & Reel 2500/Tap pe & Reel 2500/Tap pe & Reel -13 -13 -13 -13 Notes: 7. Pad layout as shown on Diodes Inc. sugg gested pad layout document d AP02001 1, which can be fou und on our website at 001.pdf. http:://www.diodes.com/datasheets/ap020 Marking In nformation n (1) SO-8 (Top View) 8 7 6 5 G : Green YY : Year : 08, 09,10~ WW : Wee ek : 01~52; 52 2 representss 52 and 53 week w nal Code X X : Intern Logo Part Nu umber 9910 fo or 7.5V 9910A for 10V 9910 X YY WW WXX 1 2 3 4 (2) SO-8EP AL9910/AL99 910A/AL9910 0-5 Document numberr: DS 35103 Rev. 3 - 2 13 of 15 ww ww.diodes.com June 2011 © Diodes Incorporated AL9910/AL9910A/AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Package Outline Dimensions (All Dimensions in mm) 0.254 0.10/0.20 3.85/3.95 5.90/6.10 (1) Package Type: SO-8 Gauge Plane Seating Plane 0.62/0.82 Detail "A" 7°~9° 0.15/0.25 1.30/1.50 0.35max. 45° 1.75max. NEW PRODUCT 7°~9° Detail "A" 0°/8° 0.3/0.5 1.27typ 4.85/4.95 5.4 8x-0.60 8x-1.55 6x-1.27 Land Pattern Recommendation (Unit: mm) (2) Package Type: SO8-EP Detail "A" Exposed pad 2.4Ref. 3.70/4.10 45¢X 0.35max. 5.90/6.10 3.85/3.95 7¢X~ 9¢X 7¢X~19¢X 1 0.15/0.25 1.30/1.50 Bottom View 0.254 0.3/0.5 0/0.13 1.27typ 1.75max. 3.3Ref. 4.85/4.95 1 0.62/0.82 Detail "A" 8x-0.60 5.4 Exposed pad 8x-1.55 6x-1.27 Land Pattem Recommendation (Unit:mm) AL9910/AL9910A/AL9910-5 Document number: DS 35103 Rev. 3 - 2 14 of 15 www.diodes.com June 2011 © 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). 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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 © 2011, Diodes Incorporated www.diodes.com AL9910/AL9910A/AL9910-5 Document number: DS 35103 Rev. 3 - 2 15 of 15 www.diodes.com June 2011 © Diodes Incorporated