BCR421UW6Q-7

BCR421UW6Q Linear LED Constant Current Regulator in SOT26 Description Features This Linear LED driver is designed to meet the stringent requirements of automotive applications.  The BCR421U monolithically integrates transistors, diodes and resistors to function as a Constant Current Regulators (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 10 kHz 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 (SC-74)   Low-Side Control Enabling PWM Input < 10kHz 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) Qualified to AEC-Q101 Standards for High Reliability PPAP Capable (Note 4) With no need for additional external components, this CCR is fully integrated into an SOT26 minimizing PCB area and component count. Applications Mechanical Data Constant Current Regulation (CCR) in:    Automotive Interior Lighting  Mood and Decorative Lighting    SOT26 (SC-74) EN Case: SOT26 (SC-74) 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) OUT BCR421U Rext (Optional) EN Rext Pin Name OUT OUT OUT EN OUT GND REXT Pin Function Regulated Output Current Enable for Biasing Transistor External Resistor for Adjusting Output Current GND Power Ground GND Top View Internal Device Schematic Top View Pin-Out Ordering Information (Note 5) Product BCR421UW6Q-7 Notes: Compliance Automotive Marking 421 Reel Size (inches) 7 Tape Width (mm) 8 Quantity per Reel 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 2.0V; VEN = 3.3V Collector-Emitter Breakdown Voltage Bias Resistor Voltage Drop (VREXT) BCR421UW6Q Document number: DS38302 Rev. 1 - 2 3 of 11 www.diodes.com Test Condition IC = 1mA — October 2015 © Diodes Incorporated BCR421UW6Q 1.4 800 1.2 700 600 Rth(JA) (°C/W) Max Power Dissipation (W) Typical Thermal Characteristics (@TA = +25°C, unless otherwise specified.) 50mm * 50mm 1oz Cu 1.0 500 0.8 400 0.6 300 0.4 25mm * 25mm 1oz Cu 200 0.2 0.0 100 0 0 50 100 100 150 Copper Area (mm ) Rth(JA) VS Cu Area 125 T amb=25°C 100 75 50 Maximum Power (W) Thermal Resistance (°C/W) Derating Curve 50mm * 50mm 1oz Cu D=0.5 Single Pulse D=0.2 D=0.05 25 D=0.1 0 100µ 1m 10m 100m 1 10 100 1k T amb=25°C 10 Single Pulse 50mm * 50mm 1oz Cu 1 100µ 1m Pulse Width (s) 10m 100m 1 10 100 1k Pulse Width (s) Transient Thermal Impedance Pulse Power Dissipation 150 125 100 Maximum Power (W) Thermal Resistance (°C/W) 1000 2 Temperature (°C) 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 100µ 1m 10m 100m 1 10 100 1k 10 25mm * 25mm 1oz Cu 1 100µ Pulse Width (s) Document number: DS38302 Rev. 1 - 2 1m 10m 100m 1 10 100 1k Pulse Width (s) Transient Thermal Impedance BCR421UW6Q Single Pulse T amb=25°C Pulse Power Dissipation 4 of 11 www.diodes.com October 2015 © Diodes Incorporated BCR421UW6Q Typical Electrical Characteristics (Continued) (@TA = +25°C, unless otherwise specified.) 0.20 Rext=6 Ohms 0.16 Rext=8 Ohms 0.12 0.10 0.08 Rext=15 Ohms VEN=3.3V Rext= open 0.00 0 1 2 3 4 5 6 7 8 VOUT = 1.4V 0.05 Rext= 30 Ohms 0.04 VOUT = 5.4V 0.15 Rext=10 Ohms IOUT (A) IOUT (A) VEN=3.3V 9 10 11 12 0.00 1 10 VOUT (V) 100 Rext (Ohms) Rext (Ohms)vs IOUT VOUT vs IOUT 0.16 0.06 VEN=3.3V -40°C 0.14 -40°C Rext=6 Ohms 0.05 IOUT (A) 0.12 IOUT (A) 25°C 25°C 0.04 85°C 0.10 0.08 85°C VEN=3.3V 0.03 Rext= 20 Ohms 0.06 0 2 4 6 VOUT (V) 8 10 12 0.02 0 2 6 8 10 12 VOUT (V) VOUT vs IOUT VOUT vs IOUT 0.15 0.02 VOUT=2V VEN=3.3V -40°C IOUT (A) IOUT (A) 0.10 0.01 0.05 25°C 2 4 Document number: DS38302 Rev. 1 - 2 Rext=10 Ohms Rext= 30 Ohms Rext= 60 Ohms Rext= open 85°C 6 VOUT (V) 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 VEN (V) VOUT vs IOUT BCR421UW6Q Rext=6 Ohms Rext=8 Ohms Rext= open 0.00 0 4 VEN vs IOUT 5 of 11 www.diodes.com October 2015 © Diodes Incorporated BCR421UW6Q Typical Electrical Characteristics (Cont.) (@TA = +25°C, unless otherwise specified.) 0.015 3.0m -40°C IEN (mA) 2.0m 1.5m IOUT = 0A 25°C Rext= open 0.010 IOUT (A) 2.5m 85°C 1.0m 25°C 85°C 0.005 -40°C VOUT=2V 500.0µ Rext= open 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0.000 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 -40°C -40°C 0.05 0.15 85°C 0.04 IOUT (A) IOUT (A) 25°C 0.03 0.02 85°C 0.10 VOUT=2V 0.05 VOUT=2V 0.01 0.00 25°C Rext=6 Ohms Rext= 20 Ohms 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 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 BCR421UW6Q Document number: DS38302 Rev. 1 - 2 6 of 11 www.diodes.com October 2015 © Diodes Incorporated BCR421UW6Q Application Information The BCR421 is 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. 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 will improve the overall accuracy of the current sense formed by the parallel connection of RINT and REXT. Figure 1 Typical Application Circuit for Linear Mode Current Sink LED Driver Two or more BCR421s 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 BCR421’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) As the output current of BCR421 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 BCR421UW6Q Document number: DS38302 Rev. 1 - 2 Refer to the thermal characteristic graphs on Page 4 for selecting the appropriate PCB copper area. 7 of 11 www.diodes.com October 2015 © Diodes Incorporated BCR421UW6Q Application Information (Continued) 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. Figure 3 Application Circuits for LED Driver with PWM Dimming Functionality Figure 4 Typical LED Current Response vs. PWM Duty Cycle for 400Hz PWM Frequency BCR421UW6Q Document number: DS38302 Rev. 1 - 2 8 of 11 www.diodes.com October 2015 © Diodes Incorporated BCR421UW6Q 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. Figure 5 Application Circuit for LED Driver with Reverse Polarity Protection 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 6 Application Circuit for LED Driver with Assured Operation Regardless of Polarity BCR421UW6Q Document number: DS38302 Rev. 1 - 2 Figure 7 Example for 350mA operation 9 of 11 www.diodes.com October 2015 © Diodes Incorporated BCR421UW6Q Package Outline Dimensions Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf 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 AP02001 at http://www.diodes.com/datasheets/ap02001.pdf 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   BCR421UW6Q Document number: DS38302 Rev. 1 - 2 X 10 of 11 www.diodes.com October 2015 © Diodes Incorporated BCR421UW6Q 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 © 2015, Diodes Incorporated www.diodes.com BCR421UW6Q Document number: DS38302 Rev. 1 - 2 11 of 11 www.diodes.com October 2015 © Diodes Incorporated