BCR420UW6 / BCR421UW6 LINEAR LED CONSTANT CURRENT REGULATOR IN SOT26 Description Features The BCR420U and BCR421U monolithically integrate transistors, diodes and resistors to function as a Constant Current Regulator (CCR) for linear LED driving. The device regulates with a preset 10mA nominal that can be adjusted with an external resistor up to 350mA. 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 multiple applications, as long as the maximum supply voltage to the device is < 40V. With the low-side control, the BCR421U has an Enable (EN) pin which can be pulse-width modulated (PWM) up to 25kHz by a microcontroller for LED dimming. LED Constant Current Regulator using NPN Emitter-Follower with Emitter Resistor to Current Limit IOUT – 10mA ± 10% Constant Current (Preset) IOUT up to 350mA Adjustable with an External Resistor VOUT – 40V Supply Voltage PD up to 1W in SOT26 / SC74R Low-Side Control Enabling PWM Input < 25kHz (BCR421U) Negative Temperature Coefficient (NTC) Reduces IOUT with With no need for additional external components, this CCR is fully integrated into an SOT26 / SC74R minimizing PCB area and component count. Mechanical Data Applications Constant Current Regulation (CCR) in: Automotive Interior Lighting Emergency Lighting Signage, Advertising, Decorative and Architectural Lighting Retail Lighting in Fridges, Freezer Cases and Vending Machines SOT26 / SC74R EN 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) Qualified to AEC-Q101 Standards for High Reliability Automotive-Compliant Parts are Available Under Separate Datasheet (BCR420UW6Q/BCR421UW6Q) 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 MILSTD-202, Method 208 Weight: 0.018 grams (Approximate) OUT BCR420U BCR421U Rext R EXT (Optional) (Optional) EN REXT Pin Name OUT OUT OUT EN OUT GND REXT GND GND Top View Internal Device Schematic Pin Function Regulated Output Current Enable for Biasing Transistor External Resistor for Adjusting Output Current Power Ground Top View Pin-Out Ordering Information (Note 4) Product BCR420UW6-7 BCR421UW6-7 Notes: Compliance AEC-Q101 AEC-Q101 Marking 420 421 Reel Size (inches) 7 7 Tape Width (mm) 8 8 Quantity per Reel 3,000 3,000 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See http://www.diodes.com/quality/lead_free.html 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. BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 1 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 Marking Information SOT26 / SC74R xxx = Part Marking (See Ordering Information) YM = Date Code Marking Y = Year (ex: D = 2016) M = Month (ex: 9 = September) xxx Date Code Key Year Code Month Code 2016 D Jan 1 2017 E Feb 2 Mar 3 2018 F Apr 4 May 5 2019 G Jun 6 2020 H Jul 7 2021 I Aug 8 Sep 9 Oct O 2022 J Nov N Dec D Absolute Maximum Ratings (Voltage relative to GND, @TA = +25°C, unless otherwise specified.) Characteristic Symbol BCR420U BCR421U Enable Voltage VEN Value 40 18 Unit V Output Current IOUT 500 mA Output Voltage VOUT 40 V VR 0.5 V Value Unit Reverse Voltage Between all Terminals Thermal Characteristics (@TA = +25°C, unless otherwise specified.) Characteristic Symbol (Note 5) (Note 6) (Note 5) (Note 6) Power Dissipation Thermal Resistance, Junction to Ambient Thermal Resistance, Junction to Lead (Note 7) Recommended Operating Junction Temperature Range Maximum Operating Junction and Storage Temperature Range 1,190 912 105 137 PD RθJA mW °C/W RθJL 50 TJ -55 to +150 TJ , TSTG -65 to +150 °C ESD Ratings (Note 8) Characteristics Electrostatic Discharge – Human Body Model Electrostatic Discharge – Machine Model Notes: Symbols BCR420U BCR421U BCR420U BCR421U HBM MM Value 500 1,000 300 400 Unit V V V V JEDEC Class 1B 1C B C 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. RθJL = Thermal resistance from junction to solder-point (at the end of the OUT leads). 8. Refer to JEDEC specification JESD22-A114 and JESD22-A115. BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 2 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 Electrical Characteristics Characteristic Collector-Emitter Breakdown Voltage Enable Current BCR420U BCR421U DC Current Gain Internal Resistor Bias Resistor Output Current Output Current at REXT = 5.1Ω BCR420U BCR421U BCR420U BCR421U BCR420U BCR421U Voltage Drop (VREXT) Minimum Output Voltage Output Current Change vs. Temperature BCR420U Output Current Change vs. Supply Voltage BCR420U BCR421U BCR421U BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 (@TA = +25°C, unless otherwise specified.) Symbol Min Typ Max Unit BVCEO 40 — — V — 1.2 — — 1.2 — hFE 200 350 500 — IC = 50mA; VCE = 1V RINT 85 105 Ω IRINT = 10mA RB — — 20 1.5 — — kΩ 9 10 11 mA VOUT = 1.4V; VEN = 24V 9 10 11 mA VOUT = 1.4V; VEN = 3.3V — 150 — mA VOUT > 2.0V; VEN = 24V — 150 — mA VOUT > 2.0V; VEN = 3.3V VDROP 0.85 0.95 1.05 V IOUT = 10mA VOUT(MIN) — 1.4 — V IOUT > 18mA — -0.2 — — -0.2 — — 1 — — 1 — IEN IOUT IOUT ΔIOUT/IOUT ΔIOUT/IOUT 3 of 13 www.diodes.com mA %/°C %/V Test Condition IC = 1mA VEN = 24V VEN = 3.3V — — VOUT > 2.0V; VEN = 24V VOUT > 2.0V; VEN = 3.3V VOUT > 2.0V; VEN = 24V VOUT > 2.0V; VEN = 3.3V June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 1.4 800 1.2 700 Rth(JA) ( C/W) Max Power Dissipation (W) Typical Thermal Characteristics BCR420/1U (@TA = +25°C, unless otherwise specified.) 50mm * 50mm 1oz Cu 1.0 o 0.8 0.6 0.4 25mm * 25mm 1oz Cu 0.2 600 500 400 300 200 100 0.0 0 50 100 0 150 100 1000 2 o Temperature ( C) Copper Area (mm ) Derating Curve Rth(JA) VS Cu Area 75 50 Maximum Power (W) o T amb=25 C 100 o Thermal Resistance ( C/W) 125 50mm * 50mm 1oz Cu D=0.5 Single Pulse D=0.2 D=0.05 25 D=0.1 0 100μ µ 1m 10m 100m 1 10 100 o T amb=25 C 10 1 100μµ 1m 1k Pulse Width (s) 1 10 100 1k Pulse Power Dissipation 150 o 125 100 Maximum Power (W) o 10m 100m Pulse Width (s) Transient Thermal Impedance Thermal Resistance ( C/W) Single Pulse 50mm * 50mm 1oz Cu T amb=25 C 25mm * 25mm 1oz Cu D=0.5 75 50 D=0.2 Single Pulse D=0.05 25 D=0.1 0 µ 100μ 1m 10m 100m 1 10 100 1k Single Pulse o 10 T amb=25 C 25mm * 25mm 1oz Cu 1 100μµ 1m 10m 100m 1 10 100 Pulse Width (s) Pulse Width (s) Transient Thermal Impedance Pulse Power Dissipation BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 4 of 13 www.diodes.com 1k June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 Typical Electrical Characteristics BCR421U (Cont.) (@TA = +25°C, unless otherwise specified.) 0.20 REXT= 6 REXT= 8 REXT= 10 0.12 0.08 REXT= 15 0.10 VEN = 3.3V REXT= open 0.00 0 1 2 3 4 5 6 7 8 VOUT = 1.4V 0.05 REXT= 30 0.04 VOUT = 5.4V 0.15 IOUT (A) IOUT (A) 0.16 VEN= 3.3V 0.00 1 9 10 11 12 10 REXT () vs IOUT VOUT vs IOUT 0.16 0.06 VEN= 3.3V o 0.14 o -40 C REXT= 6 -40 C 0.05 0.12 IOUT (A) IOUT (A) 100 REXT () VOUT (V) o 25 C o 85 C 0.10 0.08 o 0.04 25 C o 85 C VEN= 3.3V 0.03 REXT= 20 0.06 0 2 4 6 8 10 0.02 0 12 2 VOUT (V) 8 10 12 VOUT vs IOUT 0.15 0.02 VOUT= 2V VEN= 3.3V IOUT (A) -40 C 0.01 o 25 C 2 4 BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 REXT= 6 REXT= 8 REXT= open o IOUT (A) 6 VOUT (V) VOUT vs IOUT 0.00 0 4 0.10 REXT= 10 REXT= 30 0.05 REXT= 60 REXT= open o 85 C 6 8 10 12 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VOUT (V) VEN (V) VOUT vs IOUT VEN vs IOUT 5 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 Typical Electrical Characteristics BCR421U (Cont.) (@TA = +25°C, unless otherwise specified.) 0.015 3.0m o -40 C 2.5m o 2.0m 1.5m IOUT (A) IEN (mA) 25 C IOUT = 0A o 85 C REXT = open 1.0m o 25 C 0.010 o 85 C 0.005 o -40 C VOUT=2V µ 500.0μ REXT= open 0.000 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VEN (V) VEN (V) VENvs IEN VENvs IOUT 0.06 0.20 o -40 C o -40 C 0.05 0.15 o o 25 C IOUT (A) IOUT (A) 85 C 0.04 0.03 0.02 VOUT= 2V REXT= 6 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VEN (V) VEN (V) VENvs IOUT VENvs IOUT Document number: DS37667 Rev. 4 - 2 o 85 C 0.10 REXT= 20 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 BCR420UW6 / BCR421UW6 25 C 0.05 VOUT=2V 0.01 o 6 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 Typical Electrical Characteristics BCR420U (Cont.) (@TA = +25°C, unless otherwise specified.) 0.20 0.16 VEN= 24V REXT= 6 REXT= 8 IOUT (A) IOUT (A) REXT=10 0.12 VOUT= 1.4V 0.10 REXT= 15 0.08 VOUT= 5.4V 0.15 REXT= 30 0.05 0.04 VEN= 24V REXT= open 0.00 0 1 2 3 4 5 6 7 8 0.00 1 9 10 11 12 10 100 VOUT (V) REXT () VOUT vs IOUT REXT () vs IOUT 0.18 o -40 C 0.06 0.14 IOUT (A) IOUT (A) 0.16 o 25 C 0.12 o 85 C 0.10 VEN= 24V 0.08 0.06 0 0.05 o o -40 C 25 C o 85 C 0.04 VEN= 24V 0.03 REXT= 20 REXT= 6 2 4 6 8 10 0.02 12 0 2 4 6 VOUT (V) 8 VOUT vs IOUT 12 VOUT vs IOUT 0.15 0.02 REXT= 8 VOUT= 2V REXT= 10 o -40 C IOUT (A) 0.10 IOUT (A) 10 VOUT (V) 0.01 o 25 C o 85 C REXT= 30 REXT= 20 REXT= 60 0.05 REXT= open VEN= 24V REXT= open 0.00 0 2 BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 4 6 8 10 12 0.00 0 5 10 15 20 VOUT (V) VEN (V) VOUT vs IOUT VEN vs IOUT 7 of 13 www.diodes.com 25 30 June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 Typical Electrical Characteristics BCR420U (Cont.) (@TA = +25°C, unless otherwise specified.) 0.015 3.0m IOUT= 0A 2.0m REXT = open o 25 C o 85 C IOUT (A) IEN (mA) o -40 C 2.5m 1.5m 1.0m o 85 C 0.005 o -40 C o 25 C 0.010 VOUT= 2V 500.0μ µ 0.0 0 REXT= open 5 10 15 20 25 30 35 40 0.000 0 5 10 15 20 VEN (V) VEN (V) VENvs IEN VENvs IOUT 0.06 25 30 0.20 o -40 C o -40 C 0.05 0.15 o o IOUT (A) IOUT (A) 85 C 0.04 25 C 0.03 o 25 C 0.10 0.02 o 85 C 0.01 0.00 0 VOUT= 2V 0.05 VOUT= 2V REXT= 6 REXT= 20 5 10 15 20 25 30 0.00 0 15 20 25 30 VENvs IOUT VENvs IOUT Document number: DS37667 Rev. 4 - 2 10 VEN (V) VEN (V) BCR420UW6 / BCR421UW6 5 8 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 Application Information The BCR420/1 are designed for driving low current LEDs with typical LED currents of 10mA to 350mA. They provide a cost-effective 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 need 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 device comes with an internal resistor (RINT) of typically 95Ω, which in the absence of an external resistor, sets an LED current of 10mA (typical) from a VEN = 3.3V and VOUT = 1.4V for BCR421; or VEN = 24V and VOUT = 1.4V for BCR420. LED current can be increased to a desired value by choosing an appropriate external resistor, REXT. REXT (Optional) The REXT vs IOUT graphs should be used to select the appropriate resistor. Choosing a low tolerance REXT will improve the overall accuracy of the current sense formed by the parallel connection of RINT and REXT. REXT (Optional) Figure 1 Typical Application Circuit for Linear Mode Current Sink LED Driver Two or more BCR420/1s can be connected in parallel to construct higher current LED strings as shown in Figure 2. Consideration of the expected linear mode power dissipation must be factored into the design, with respect to the BCR420/1’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. VOUT = VS – VLED PD = (VOUT × ILED) + (VEN × IEN) REXT (Optional) REXT (Optional) As the output current of BCR420/1 increases, it is necessary to provide appropriate thermal relief to 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: PD = ( TJ(MAX) - TA) / RθJA Figure 2 Application Circuit for Increasing LED Current BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 Refer to the thermal characteristic graphs on Page 4 for selecting the appropriate PCB copper area. 9 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 Application Information (Cont.) PWM dimming can be achieved by driving the EN pin. 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 analog circuitry; typical circuit is shown in Figure 3. Figure 4 is a typical response of LED current vs. PWM duty cycle on the EN pin. PWM up to 25kHz with duty cycle of 0.5% (dimming range 200:1). This is above the audio band minimizing audible power supply noise. REXT (Optional) Figure 3 Application Circuits for LED Driver with PWM Dimming Functionality Figure 4 Typical LED Current Response vs. PWM Duty Cycle for 25kHz PWM Frequency (Dimming Range 200:1) BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 10 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 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. A circuit example is presented in Figure 5 which protects the light engine although it will not function until the problem is diagnosed and corrected. An SDM10U45LP (0.1A/45V) is shown, providing exceptionally low VF for its package size of 1mm x 0.6mm. Other reverse voltage ratings are available from 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, an alternative approach shown in Figure 6, provides reverse polarity protection and corrects the reversed polarity, allowing the light engine to function. REXT (Optional) The BAS40BRW incorporates four low VF Schottky diodes in a single package, reducing the power dissipated and maximizes the voltage across the LED stack. Figure 7 shows an example configuration for 350mA operation. In such higher current configurations adequate enable current is provided by increasing the enable voltage. Figure 5 Application Circuit for LED Driver with Reverse Polarity Protection REXT (Optional) Figure 6 Application Circuit for LED Driver with Assured Operation Regardless Of Polarity BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 REXT = 2.1 Figure 7 Example for 350mA Operation 11 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 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 Dimensions Value (in mm) C 2.40 C1 0.95 G 1.60 X 0.55 Y 0.80 Y1 3.20 C Y X BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 12 of 13 www.diodes.com June 2016 © Diodes Incorporated BCR420UW6 / BCR421UW6 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). 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. 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Copyright © 2016, Diodes Incorporated www.diodes.com BCR420UW6 / BCR421UW6 Document number: DS37667 Rev. 4 - 2 13 of 13 www.diodes.com June 2016 © Diodes Incorporated