AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER Description Pin Assignments The AL5801 combines a 100V N-channel MOSFET with a prebiased NPN transistor to make a simple, small footprint LED driver. (Top View) REXT ADVANCE INFORMATION The LED current is set by an external resistor connected from REXT pin (4) to GND pin (6). The internal pre-biased transistor develops approximately 0.56V across the external resistor. The AL5801 open-drain output can operate from 1.1V to 100V enabling it to operate 5V to 100V power supplies without additional components. PWM dimming of the LED current can be achieved by driving the BIAS pin (1) with an external, open-collector NPN transistor or open-drain N-channel MOSFET. The AL5801 is available in a SOT26 package and is ideal for driving LED currents up to 350mA. SOT26 Features Applications • Feedback pin reference voltage VRSET = 0.56V at +25ºC • Linear LED drivers • -40 to +125ºC temperature range • LED signs • 1.1V to 100V open-drain output • Offline LED luminaries • Negative temperature VRSET co-efficient automatically reduces the LED current at high temperatures • Lead-Free Finish; RoHS Compliant (Notes 1 & 2) • Halogen and Antimony Free. “Green” Device (Note 3) • Low thermal impedance SOT26 package with copper lead frame Notes: 1. EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. All applicable RoHS exemptions applied. 2. See http://www.diodes.com for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free. 3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds. Typical Application Circuit AL5801 Document number: DS35555 Rev. 2 - 2 1 of 12 www.diodes.com June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER ADVANCE INFORMATION Pin Description Pin Number Name 1 BIAS 2 FB 3 OUT 4 REXT 5 COMP 6 GND Function Biases the open-Drain output MOSFET Feedback pin Open-Drain LED driver output Current sense pin. LED current sensing resistor should be connected from here to GND Compensation pin. Connect COMP pin to REXT pin and insert a 1nF ceramic capacitor from COMP pin to FB pin for improved transient stability Ground reference point for setting the LED current Functional Block Diagram Figure 1 Block Diagram Absolute Maximum Ratings Symbol Values Unit VOUT Output voltage relative to GND 100 V VBIAS BIAS voltage relative to GND (Note 4) 20 V VFB VCOMP VREXT IOUT Characteristics FB voltage relative to GND 6 V COMP voltage relative to GND 6 V REXT voltage relative to GND Output current 6 V 350 mA TJ Operating junction temperature -40 to +150 °C TST Storage temperature -55 to +150 °C These are stress ratings only. Operation outside the absolute maximum ratings may cause device failure. Operation at the absolute maximum rating for extended periods may reduce device reliability. Notes: 4. With pins 5 and 6 connected together AL5801 Document number: DS35555 Rev. 2 - 2 2 of 12 www.diodes.com June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER ADVANCE INFORMATION Package Thermal Data Characteristic Power Dissipation (Note 5) @ TA = 25°C Power Dissipation (Note 6) @ TA = 25°C Power Dissipation (Note 7) @ TA = 25°C Power Dissipation (Note 8) @ TA = 25°C Thermal Resistance, Junction to Ambient Air (Note 5) @ TA = 25°C Thermal Resistance, Junction to Ambient Air (Note 6) @ TA = 25°C Thermal Resistance, Junction to Ambient Air (Note 7) @ TA = 25°C Thermal Resistance, Junction to Ambient Air (Note 8) @ TA = 25°C Notes: Symbol Value 0.75 0.70 0.85 1.05 165 180 145 120 PD RθJA Unit W °C/W 5. Device mounted on 15mm x 15mm 2oz copper board. 6. Device mounted on 25mm x 25mm 1oz copper board. 7. Device mounted on 25mm x 25mm 2oz copper board. 8. Device mounted on 50mm x 50mm 2oz copper board. Recommended Operating Conditions Symbol Parameter Min Max Unit VBIAS Supply voltage range 3.5 20 VOUT OUT voltage range 1.1 100 ILED LED pin current (Note 9) 25 350 mA Operating ambient temperature range -40 125 °C TA Notes: V 9. Subject to ambient temperature, power dissipation and PCB. NMOSFET Electrical Characteristics: (Q1) (@TA = +25°C unless otherwise specified) Characteristic OFF CHARACTERISTICS Drain-Source Breakdown Voltage Zero Gate Voltage Drain Current Gate-Source Leakage ON CHARACTERISTICS Gate Threshold Voltage Symbol Min Typ Max Unit BVDSS IDSS IGSS 100 ⎯ ⎯ ⎯ ⎯ ⎯ ⎯ 1 ±100 V μA nA VGS = 0V, ID = 250μA VDS = 60V, VGS = 0V VGS = ±20V, VDS = 0V VGS(th) 2.0 RDS (ON) ⎯ 4.1 0.85 0.99 V Static Drain-Source On-Resistance gfs VSD ⎯ ⎯ ⎯ ⎯ ⎯ 0.9 0.89 ⎯ 1.1 S V VDS = VGS, ID = 250μA VGS = 10V, ID = 1.5A VGS = 6V, ID = 1A VDS = 15V, ID = 1A VGS = 0V, IS = 1.5A Ciss Coss Crss ⎯ ⎯ ⎯ 129 14 8 ⎯ ⎯ ⎯ pF pF pF Forward Transconductance Diode Forward Voltage DYNAMIC CHARACTERISTICS Input Capacitance Output Capacitance Reverse Transfer Capacitance AL5801 Document number: DS35555 Rev. 2 - 2 3 of 12 www.diodes.com Ω Test Condition VDS = 50V, VGS = 0V f = 1.0MHz June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER Pre-bias Transistor Electrical Characteristics: (Q2) (@TA = +25°C unless otherwise specified) Characteristic (Note 10) Symbol VI(off) VI(on) VO(on) IO(off) G1 R1 R2/R1 Output Voltage Output Current DC Current Gain Input Resistance Resistance Ratio Notes: Typ 0.05 4.7 10 Max 1.5 0.3 0.5 6.2 12 Unit V V V μA kΩ - Test Condition VCC = 5V, IO = 100μA VCC = 0.3V, IO = 5mA IO/II = 5mA/0.25mA VCC = 50V, VI = 0V VO = 5V, IO = 10mA - 10. Short duration pulse test used to minimize self-heating effect. Thermal Characteristics 1.2 1.2 1.0 1.0 MAX POWER DISSIPATION (W) MAX POWER DISSIPATION (W) 50mm x 50mm (2oz. FR4) 0.8 25mm x 25mm (2oz. FR4) 15mm x 15mm (2oz. FR4) 0.6 0.4 0.2 0 0 25 50 75 100 TEMPERATURE (°C) Figure 2 Derating Curve 125 TA = 25°C 2oz. FR4 0.8 0.6 0.4 0.2 0 150 0 500 1,000 1,500 2,000 2 COPPER AREA (mm ) Figure 3 Area vs. Max Power 2,500 180 160 JUNCTION TO AMBIENT AIR THERMAL RESISTANCE (°C/W) ADVANCE INFORMATION Input Voltage Min 0.4 80 3.2 8 140 T A = 25°C 25mm x 25mm 1oz. FR4 120 D = 0.5 100 80 D = 0.1 D = 0.2 60 D = 0.05 Single Pulse 40 20 0 0.0001 AL5801 Document number: DS35555 Rev. 2 - 2 0.001 0.01 0.1 1 10 PULSE WIDTH (s) Figure 4 Transient Thermal Impedance 4 of 12 www.diodes.com 100 1,000 June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER Typical Performance Characteristics 0.40 400 Ibias = 0.1mA 300 0.25 250 IOUT (mA) IOUT (A) 0.30 0.20 200 150 REXT = 3.75Ω 0.10 100 0.05 0 Ibias = 0.1mA 350 REXT = 1.6Ω 0.15 50 REXT = 11.6Ω REXT = 22.7Ω 0 1 2 0 1 3 10 REXT (Ω) Figure 6 Output Current vs. REXT VOUT (V) Figure 5 Output Current vs. VOUT 0.5 TA = -40°C T A = -40°C 0.15 T A = 25°C TA = 25°C IOUT (A) 0.3 IOUT (A) 100 0.20 0.4 TA = 85°C 0.2 Ibias = 0.1mA T A = 85°C 0.10 0.05 REXT = 1.6Ω 0.1 Ibias = 0.1mA REXT = 3.75Ω 0 0 1 2 0 3 0 VOUT (V) Figure 7 Output Current vs. VOUT 0.06 4 6 8 VOUT (V) Figure 8 Output Current vs. VOUT 10 TA = -40°C 0.030 T A = -40°C 0.05 0.025 IOUT (A) TA = 25° C 0.04 TA = 85° C 0.03 0.02 TA = 25°C 0.020 T A = 85°C 0.015 0.010 Ibias = 0.1mA 0.01 0 2 0.035 0.07 IOUT (A) ADVANCE INFORMATION 0.35 0 5 10 15 VOUT (V) Figure 9 Output Current vs. VOUT AL5801 Document number: DS35555 Rev. 2 - 2 Ibias = 0.1mA 0.005 REXT = 11.6Ω 5 of 12 www.diodes.com 0 REXT = 22.7Ω 0 5 10 15 VOUT (V) Figure 10 Output Current vs. VOUT 20 June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER 800 400 700 350 600 300 500 250 IOUT (mA) VREXT (mV) ADVANCE INFORMATION Typical Performance Characteristics 400 300 200 50mm x 50mm (2oz. FR4) 25mm x 25mm (2oz. FR4) 200 15mm x 15mm (2oz. FR4) 150 100 Ibias = 0.1mA Vbias = 5V 100 0 -50 Ibias = 0.1mA T A = 85°C 50 0 50 100 150 JUNCTION TEMPERATURE (°C) Figure 11 VREXT vs. Junction Temperature AL5801 Document number: DS35555 Rev. 2 - 2 6 of 12 www.diodes.com 0 1 10 VOUT (V) Figure 12 Output Current vs. VOUT 100 June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER Application Information controls the gate voltage of MOSFET Q1. Q1 operates in linear mode to regulate the LED current. The LED current is ADVANCE INFORMATION ILED = VRSET / REXT where VRSET is the VBE of Q2. VBE is 0.56V typical at a 25ºC device temperature. See Figure 11 for the variation of VBE with Q2’s junction temperature at IBIAS = 0.1mA. VBE has a negative temperature coefficient which reduces the LED current as the device warms up, protecting the LED(s). RBIAS should be chosen to drive 0.1mA current into the BIAS pin RBIAS = ( VCC – 3.75V ) / 0.1mA From the above equation, for any required LED current the necessary external resistor REXT can be calculated from REXT = VRSET / ILED The expected linear mode power dissipation must be factored into the design consideration. The power dissipation across the device can be calculated by taking the maximum supply voltage less the minimum voltage across the LED string. VDS(Q1) = VCC(max) – VLED(min) – VRSET PD = VDS(Q1) * ILED As the output LED current of AL5801 increases so will its power dissipation. The power dissipation will cause the device temperature to rise above ambient, TA, by an amount determined by the package thermal resistance, RθJA. Figure 13 Typical Application Circuit for Linear Mode Current Sink LED Driver The AL5801 is designed for driving high brightness LEDs with typical LED current up to 350mA. It provides a more cost effective way for driving low current LEDs when compared against more complex switching regulator solutions. Furthermore, it reduces the PCB board area of the solution because there is no need for external components like inductors, capacitors and/or switching diodes. Figure 13 shows a typical application circuit diagram for driving an LED or a string of LEDs. The NPN transistor Q2 measures the LED current by sensing the voltage across an external resistor REXT. Q2 uses its VBE as reference to set the voltage across REXT and AL5801 Document number: DS35555 Rev. 2 - 2 Therefore, the power dissipation supported by the device is dependent upon the PCB board material, the copper area and the ambient temperature. The maximum dissipation the device can handle is given by: PD = ( TJ(MAX) - TA ) / RθJA TJ(MAX) = 150ºC is the maximum device junction temperature. Refer to the thermal characteristic graphs in Figure 2 to 4 for selecting the appropriate PCB copper area. Figure 12 shows the current capabilities of the AL5801 at 25ºC with different PCB copper area heat sinks. 7 of 12 www.diodes.com June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER ADVANCE INFORMATION Constant LED Current Temperature Compensation Variation in the junction temperature of Q2 will cause variations in the value of controlled LED current ILED. The base-emitter VBE voltage of Q2 decreases with increasing temperature at a rate of approximately 2mV/ºC. Figure 14 shows a simple temperature compensation network, which comprises of an NTC thermistor and resistor Rbase, for stabilizing the LED current. The RTH resistance of the NTC thermistor at room temperature is recommended as 10kΩ. The value of base resistor Rbase is set to be 470Ω. Q2’s base current is obtained as IB(Q2) = ( VRSET - VBE(Q2) ) / Rbase - VBE(Q2) / RTH = ( 0.62V - 0.56 ) / 470Ω - 0.56V / 10kΩ = 72µA T When VBE(Q2) is changed to VBE as the temperature increases to TºC, the thermistor resistance at TºC required to compensate this variation is given by T T T RTH = VBE / (( VRSET - VBE ) / Rbase - IB(Q2) ) At -2mV/ºC, VBE(Q2) reduces to 0.44V from 0.56V as the temperature increases from 25ºC to 85ºC. From the above equation, the thermistor’s resistance at 85ºC to keep the same output current is given by 85 RTH = 0.44V / (( 0.62V – 0.44V ) / 470Ω - 72uA ) = 1.4kΩ The NTC thermistor is chosen for compensation whose resistance is 10kΩ at 25ºC and 1.38kΩ at 85ºC with a β value of 3530. Figure 15 shows the ILED variation with temperature with and without temperature compensation. Figure 14 Constant LED Current Temperature Compensation for AL5801 The voltage drop VRSET in the sense resistor REXT should be set to be 40 to 100mV higher than the VBE(Q2) at 25ºC. Figure 11 shows the typical VBE(Q2) is 0.56V at room temperature with 0.1mA IBIAS, so VRSET is selected to be 0.62V. With the VRSET chosen, the sense resistor value for 350mA ILED is determined by REXT = VRSET / ILED = 0.62V / 350mA = 1.77Ω So a standard resistor value of 1.78Ω with 1% tolerance is used. AL5801 Document number: DS35555 Rev. 2 - 2 Figure 15 LED Current Variation with and without Temperature Compensation 8 of 12 www.diodes.com June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER PWM Dimming ADVANCE INFORMATION PWM dimming can be achieved by driving the BIAS pin (1). An external open-collector NPN transistor or open-drain N-channel MOSFET can be used to drive the BIAS pin as shown in Figure 16. Dimming is achieved by turning the LEDs ON and OFF for a portion of a single cycle. The PWM signal can be provided by a micro-controller or by analog circuitry. Figure 17 shows the LED current against the PWM signal duty ratio when the AL5801 is used to drive three series connected LEDs from a 12V supply. The PWM dimming frequency is set to 200Hz. The PWM signal is supplied to the open-Drain small signal MOSFET’s gate as shown in Figure 16a. The BIAS pin signal is an inversion of the PWM drive to the MOSFET’s gate. Therefore, a PWM signal duty cycle of 0% provides the maximum LED current. Sufficiently large PCB copper area is used for heat sinking of the AL5801 in order to minimize the device self-heating at 25ºC ambient. (a) Figure 17 LED Current against PWM Dimming Signal Duty Ratio at 200Hz PWM Frequency (b) Figure 16 Application Circuits for LED Driver with PWM Dimming Functionality (a) MOSFET driving and (b) Transistor driving AL5801 Document number: DS35555 Rev. 2 - 2 9 of 12 www.diodes.com June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER Ordering Information (Note 11) Package Code W6 Device AL5801W6-7 7” Tape and Reel Quantity Part Number Suffix 3,000/Tape & Reel -7 Packaging (Note 11) SOT26 Green ADVANCE INFORMATION Notes: 11. For packaging details, go to our website at http://www.diodes.com Marking Information L100 = Product Type Marking Code YM = Date Code Marking Y = Year (ex: Y = 2012) M = Month (ex: 9 = September) Date Code Key Year 2012 Code Z Month Code Jan 1 2013 A Feb 2 Mar 3 AL5801 Document number: DS35555 Rev. 2 - 2 2014 B Apr 4 May 5 2015 C Jun 6 2016 D Jul 7 10 of 12 www.diodes.com Aug 8 2017 E Sep 9 Oct O 2018 F Nov N Dec D June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER Package Outline Dimensions A SOT26 Dim Min Max Typ A 0.35 0.50 0.38 B 1.50 1.70 1.60 C 2.70 3.00 2.80 D ⎯ ⎯ 0.95 H 2.90 3.10 3.00 J 0.013 0.10 0.05 K 1.00 1.30 1.10 L 0.35 0.55 0.40 M 0.10 0.20 0.15 0° 8° α ⎯ All Dimensions in mm ADVANCE INFORMATION B C H K M J L D Suggested Pad Layout C2 Z C2 C1 G Y Dimensions Value (in mm) Z 3.20 G 1.60 X 0.55 Y 0.80 C1 2.40 C2 0.95 X AL5801 Document number: DS35555 Rev. 2 - 2 11 of 12 www.diodes.com June 2012 © Diodes Incorporated AL5801 100V, ADJUSTABLE CURRENT SINK LINEAR LED DRIVER IMPORTANT NOTICE ADVANCE INFORMATION 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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