BCR401UW6 10 to 100mA LED CONSTANT CURRENT REGULATOR in SOT26 (SC74R) Description Features The BCR401U monolithically integrates a transistor, diodes and resistors to function as a Constant Current Regulator (CCR) for LED driving. The device regulates with a preset 10mA nominal that can be adjusted with external resistor up to 100mA. It is designed for driving LEDs in strings and will reduce current at increasing temperatures to self-protect. Operating as a series linear CCR for LED string current control, it can be used in applications with supply voltages up to 40V. * * * * * * * With no need for additional external components, this CCR is fully integrated into a SOT26 (SC74R) minimizing PCB area and component count. * * * * Applications Constant Current Regulation (CCR) in: * * * Emergency Lighting Signage, Advertising, Decorative and Architectural Lighting Retail Lighting in Fridge, Freezer Case and Vending Machines * * LED Constant Current Regulator Using PNP Emitter-Follower with Emitter Resistor to Current Limit IOUT = 10mA 10% Constant Current (Preset) IOUT up to 100mA Adjustable with an External Resistor VS - 40V Supply Voltage PD up to 1W in SOT26 (SC74R) LED Dimming Using PWM up to 25kHz Negative Temperature Coefficient (NTC) Reduces IOUT with Increasing Temperature Parallel Devices to Increase Regulated Current Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. "Green" Device (Note 3) For automotive applications requiring specific change control (i.e.: parts qualified to AEC-Q100/101/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please refer to the related automotive grade (Qsuffix) part. A listing can be found at https://www.diodes.com/products/automotive/automotiveproducts/. This part is qualified to JEDEC standards (as references in AEC-Q) for High Reliability. https://www.diodes.com/quality/product-definitions/ An Automotive-Compliant Part is Available Under Separate Datasheet (BCR401UW6Q) Mechanical Data * * * * * Case: SOT26 (SC74R) Case Material: Molded Plastic. "Green" Molding Compound. UL Flammability Rating 94V-0 Moisture Sensitivity: Level 1 per J-STD-020 Terminals: Finish - Matte Tin Plated Leads, Solderable per MIL-STD-202, Method 208 Weight: 0.018 grams (Approximate) SOT26/SC74R Pin Name VS OUT Rext GND Top View Internal Device Schematic Pin Function Supply Voltage Regulated Output Current External resistor for adjusting Output Current Power Ground Top View Pin-Out Ordering Information (Note 4) Product BCR401UW6-7 Notes: Marking 401 Reel Size (inches) 7 Tape Width (mm) 8 Quantity per Reel 3000 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant. 2. See https://www.diodes.com/quality/lead-free/ 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. 4. For packaging details, go to our website at http://www.diodes.com/products/packages.html. BCR401UW6 Document number: DS38542 Rev. 4 - 2 1 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Marking Information SOT26 (SC74R) 401 = Part Marking (See Ordering Information) YM = Date Code Marking Y = Year (ex: H = 2020) M = Month (ex: 9 = September) 401 Date Code Key Year 2020 Code H Month Code 2021 I Jan 1 2022 J Feb 2 Mar 3 2023 K 2024 L Apr 4 May 5 2025 M 2026 N Jun 6 Jul 7 2027 O Aug 8 2028 P Sep 9 Oct O 2029 Q 2030 R Nov N Dec D Absolute Maximum Ratings (Voltage relative to GND, @TA = +25C, unless otherwise specified.) Characteristic Symbol Value Unit Supply Voltage VS 40 V Output Current IOUT 100 mA Output Voltage VOUT 40 V VR 0.5 V Value 1,190 912 105 137 Unit Reverse voltage between all terminals Thermal Characteristics Characteristic Power Dissipation Thermal Resistance, Junction to Ambient Thermal Resistance, Junction to Lead Symbol (Note 5) (Note 6) (Note 5) (Note 6) PD RJA (Note 7) RJL 50 TJ -55 to +150 TJ , TSTG -65 to +150 Recommended Operating Junction Temperature Range Maximum Operating Junction and Storage Temperature Range mW C/W C ESD Ratings (Note 8) Characteristics Electrostatic Discharge - Human Body Model Electrostatic Discharge - Machine Model Notes: Symbols Value Unit JEDEC Class ESD HBM ESD MM 800 300 V V 1B B 5. For a device mounted with the OUT leads on 50mm x 50mm 1oz copper that is on a single-sided 1.6mm FR4 PCB; device is measured under still air conditions while operating in steady-state. 6. Same as Note 5, except mounted on 25mm x 25mm 1oz copper. 7. RJL = Thermal resistance from junction to solder-point (at the end of the OUT leads). 8. Refer to JEDEC specification JESD22-A114 and JESD22-A115. BCR401UW6 Document number: DS38542 Rev. 4 - 2 2 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Electrical Characteristics (@TA = +25C, unless otherwise specified.) Characteristic Symbol Min Typ Max Unit BVCEO 40 -- -- V IC = 1mA GND (Enable) Current IGND 340 420 500 A VS = 10V; VOUT = Open GND (Enable) Current IGND -- 380 -- A VS = 10V; VOUT = 8.6V DC Current Gain hFE 100 220 470 -- IC = 50mA; VCE = 1V Internal Resistor RINT 78 91 104 IRINT = 10mA IOUT 9 10 11 mA VDROP -- 0.91 -- V IOUT = 10mA V IOUT > 8mA Collector-Emitter Breakdown Voltage Output Current (Nominal) Voltage Drop (VREXT) Lowest Sufficient Supply Voltage (VS-VOUT) VSMIN -- 1.4 -- Test Condition VOUT = 8.6V; VS = 10V Output Current Change vs. Temperature IOUT/IOUT -- -0.25 -- %/C VS = 10V Output Current Change vs. Supply Voltage IOUT/IOUT -- 1 -- %/V VS = 10V BCR401UW6 Document number: DS38542 Rev. 4 - 2 3 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Max Power Dissipation (W) Typical Thermal Characteristics (@TA = +25C, unless otherwise specified.) 1.4 800 1.2 700 50mm * 50mm 1oz Cu 600 Rth(JA) (C/W) 1.0 500 0.8 400 0.6 300 25mm * 25mm 1oz Cu 0.4 200 0.2 0.0 100 0 50 100 0 150 Temperature (C) 100 Copper Area (mm2) 1000 Rth(JA) VS Cu Area Derating Curve 100 Tamb=25C 50mm * 50mm 1oz Cu Maximum Power (W) Thermal Resistance (C/W) 125 75 D=0.5 50 Single Pulse D=0.2 D=0.05 25 D=0.1 0 100 1m 10m 100m 1 10 Pulse Width (s) 100 1k Single Pulse Tamb=25C 50mm * 50mm 1oz Cu 10 1 100 1m Transient Thermal Impedance 10m 100m 1 10 Pulse Width (s) 100 1k Pulse Power Dissipation 125 100 75 Tamb=25C 25mm * 25mm 1oz Cu Maximum Power (W) Thermal Resistance (C/W) 150 D=0.5 50 D=0.2 Single Pulse D=0.05 25 0 100 1m D=0.1 10m 100m 1 10 Pulse Width (s) 100 1k Document number: DS38542 Rev. 4 - 2 Single Pulse 1 100 1m Transient Thermal Impedance BCR401UW6 Tamb=25C 25mm * 25mm 1oz Cu 10 10m 100m 1 10 Pulse Width (s) 100 1k Pulse Power Dissipation 4 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Typical Electrical Characteristics (Continued) (@TA = +25C, unless otherwise specified.) Rext=18 Ohms Rext=22 Ohms 50 IOUT (mA) IOUT (mA) 80 60 VS-VOUT=1.4V Rext=15 Ohms 60 40 20 1 Rext=51 Ohms Rext= 33 Ohms 5 10 15 20 25 VS (V) 30 35 40 20 0 40 25C 30 10 Rext= 100 -40C 20 15 VS-VOUT=1.4V & VS = 10V 20 -20 Rext=51 Ohms -25 0 25 Rext= 100 50 75 TJ (C) Rext= OPEN 10 5 0 0 100 125 150 25C IS (mA) IOUT (mA) 10 8 VS-VOUT=1V 6 4 2 00 5 10 15 20 25 VS (V) 30 35 40 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.00 VS vs IOUT BCR401UW6 Document number: DS38542 Rev. 4 - 2 85C 150C VS-VOUT=1.4V 5 10 15 20 Rext= OPEN 25 VS (V) 30 35 40 VS vs IOUT VS-VOUT=1.4V to 2V 12 80 100 -40C TJ vs IOUT 14 60 Rext=22 Ohms 40 0 Rext= 33 Ohms 40 Rext (Ohms) Rext (Ohms)vs IOUT IOUT (mA) IOUT (mA) 60 Rext=15 Ohms Rext=18 Ohms 150C VS=10V VS vs IOUT 80 85C VS-VOUT=1.4V 85C 25C 5 10 15 20 25 VS (V) 30 -40C 35 40 VS vs IS 5 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Application Information The BCR401/2/5 are designed for driving low-current LEDs with typical LED currents of 10mA to 100mA. The devices provide a costeffective way for driving low-current LEDs compared with more complex switching regulator solutions. Furthermore, they reduce the PCB board area of the solution as there is no requirement for external components like inductors, capacitors, and switching diodes. Figure 1 shows a typical application circuit diagram for driving an LED or string of LEDs. The devices come with an internal resistor (RINT) of typically 91, 44, 16.5 which, in the absence of an external resistor, sets an LED current of 10mA, 20mA, 50mA, respectively. LED current can be increased to a desired value by choosing an appropriate external resistor, REXT. The REXT vs. IOUT graphs should be used to select the appropriate resistor. Choosing a low tolerance REXT improves the overall accuracy of the current sense formed by the parallel connection of RINT and REXT. Figure 1. Typical Application Circuit for BCR40x LED Driver The negative temperature coefficient of the BCR series allows easy paralleling of BCR410/2/5s. In applications where current sharing is required, either due to high current requirements of LED strings or for power sharing, two or more BCR401/2/5s can be connected in parallel as shown in Figure 2. Power dissipation capability must be factored into the design with respect to the BCR401/2/5's thermal resistance. The maximum voltage across the device can be calculated by taking the maximum supply voltage and subtracting the voltage across the LED string. VDEVICE = VS - VOUT PD = (VDEVICE x ILED) + (VS x IGND) As the output current of BCR401/2/5 increases, it is necessary to connect an appropriate heat sink to the OUT pins of the device. 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: Figure 2. Application Circuit for Increasing LED Current PD = (TJ(MAX) - TA) / RJA See the thermal characteristic graphs on page 4 for selecting the appropriate PCB copper area. BCR401UW6 Document number: DS38542 Rev. 4 - 2 6 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Application Information (continued) PWM is the most pursued method for LED dimming. In the PWM method, dimming is achieved by turning the LEDs ON and OFF for a portion of a single cycle. PWM dimming can be achieved by enabling/disabling the LED driver itself (see Figure 3a, Figure 3b) or by the switching the power path on and off (see Figure 3c). The PWM signal can be provided by a microcontroller or analog circuitry. Figure 3 shows typical circuits, and Figure 4 is a typical response of LED current vs. PWM duty cycle. The PWM method shown in Figure 3b is used for generating the graphs. Figure 3a Figure 3b Figure 3c Figure 3a, 3b, 3c. Application Circuits for LED Driver with PWM Dimming Functionality BCR401UW6 Document number: DS38542 Rev. 4 - 2 7 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Application Information (cont.) PWM resolution at 25kHz LED current (mA) 60 50 40 30 calculated DC current 20 Measured DC current 10 0 0 20 40 60 80 100 Duty ratio % PWM resolution at 10kHz LED current (mA) 60 50 40 30 calculated DC current 20 Measured DC current 10 0 0 20 40 60 80 100 Duty ratio % PWM resolution at 1kHz 60 LED current (mA) 50 40 30 calculated DC current 20 Measured DC current 10 0 0 20 40 60 80 100 Duty ratio % Figure 4. Typical LED Current Response vs. PWM Duty Cycle for 25kHz, 10kHz, and 1kHz PWM Frequency (see Figure 3b) BCR401UW6 Document number: DS38542 Rev. 4 - 2 8 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Application Information (Cont.) The error between the calculated theoretical value and the measured value is due to the turn on and turn off times of the BCR401/2/5. There is a small contribution from the switches (a pre-biased transistor or a MOSFET) shown in Figure 3a and Figure 3b towards the total turn-on and turn-off times of the BCR401/2/5. It is recommended to keep the external switching delays to the lowest possible value to improve PWM accuracy. The typical switching times of the BCR401/2/5 for the configuration shown in Figure 3b are: Turn-On Time = 200ns Turn-Off Time = 10s Please refer to the Figure 5 and Figure 6 for the switching time performance. The percentage contribution of these switching delays increases with increasing frequency and decreasing duty ratio as shown in Figure 4. Figure 5. Turn-On Time of BCR401/2/5 (PWM Method in Figure 3b) Figure 6. Turn-On Time of BCR401/2/5 (PWM Method in Figure 3c) Where possible, the switching performance of the BCR401/2/5 can be significantly improved by switching the power path as shown in Figure 3c. Figure 7 shows the resulting turn-off time. This results in an improved PWM resolution at 25kHz as shown in Figure 8. Turn-Off Time = ~200ns BCR401UW6 Document number: DS38542 Rev. 4 - 2 9 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Application Information (Cont.) Figure 7. Turn-Off Time of BCR401/2/5 while Switching the Power Path (see Figure 3c) Yellow PWM Signal Green LED Current Blue No Connection Made to this Probe Channel PWM resolution at 25kHz 60 LED current (mA) 50 40 30 calculated DC current 20 Measured DC current 10 0 0 20 40 60 80 100 Duty ratio % Figure 8. PWM Resolution with Power Path Switching (see Figure 3c) BCR401UW6 Document number: DS38542 Rev. 4 - 2 10 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Application Information (Cont.) To remove the potential of incorrect connection of the power supply damaging the lamp's LEDs, many systems use some form of reverse polarity protection. One solution for reverse input polarity protection is to simply use a diode with a low VF in line with the driver/LED combination. The low VF increases the available voltage to the LED stack and dissipates less power. Figure 9 shows a circuit example which protects the light engine, although it will not function until the problem is diagnosed and corrected. An SDM10U45LP (0.1A/45V) is shown, which provides exceptionally low VF for its package size of 1mm x 0.6mm. Other reverse voltage ratings are available on Diodes Incorporated's website, such as the SBR02U100LP (0.2A/100V) or SBR0220LP (0.2A/20V). While automotive applications commonly use this method for reverse battery protection, Figure 10 shows an alternative approach shown that provides reverse polarity protection and corrects the reversed polarity, allowing the light engine to function. The BAS40BRW incorporates four low VF Schottky diodes in a Figure 9. Application Circuit for LED Driver with Reverse Polarity Protection single package, reducing the power dissipated and maximizing the voltage across the LED stack. Figure 10. Application Circuit for LED Driver with Assured Operation Regardless of Polarity BCR401UW6 Document number: DS38542 Rev. 4 - 2 11 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 Package Outline Dimensions Please see http://www.diodes.com/package-outlines.html for the latest version. SOT26 (SC74R) D E1 SOT26 (SC74R) Dim Min Max Typ A1 0.013 0.10 0.05 A2 1.00 1.30 1.10 A3 0.70 0.80 0.75 b 0.35 0.50 0.38 c 0.10 0.20 0.15 D 2.90 3.10 3.00 e 0.95 e1 1.90 E 2.70 3.00 2.80 E1 1.50 1.70 1.60 L 0.35 0.55 0.40 a 8 a1 7 All Dimensions in mm E b a1 e1 A2 A3 A1 Seating Plane e L c a Suggested Pad Layout Please see http://www.diodes.com/package-outlines.html for the latest version. SOT26 (SC74R) C1 Y1 G C Y Dimensions Value (in mm) C 2.40 C1 0.95 G 1.60 X 0.55 Y 0.80 Y1 3.20 X BCR401UW6 Document number: DS38542 Rev. 4 - 2 12 of 13 www.diodes.com February 2020 (c) Diodes Incorporated BCR401UW6 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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