TSCR421CX6H RFG

TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor Linear Constant Current Regulated LED Driver DESCRIPTION FEATURES The TSCR420 & TSCR421 are Low-Side 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 300mA. It is designed for driving LEDs in strings and will reduce ● AEC-Q100 qualified with the following results: Device temperature grade 1: -40°C to 125°C Device HBM ESD classification level H2 Device CDM ESD classification level C6 ● LED drive current preset to 10mA ● Continuous output current up to 300mA with an external resistor ● Very low enable current ● Easy paralleling of drivers to increase current ● Supply voltage up to 40V ● Digital PWM input up to 10kHz (TSCR421) ● Good temperature coefficient vs. output current ● Compliant to RoHS Directive 2011/65/EU and in accordance to WEEE 2002/96/EC. ● Halogen-Free according to IEC 61249-2-21 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 2.0V, VEN=24V TSCR421 VOUT>2.0V, VEN=3.3V IOUT mA Voltage Drop (VREXT) IOUT=10mA VDROP 0.85 0.95 1.05 V Minimum Output Voltage IOUT>18mA VOUT(MIN) -- 1.4 -- V -- -0.07 -- -- -0.07 -- -- 0.33 -- -- 0.33 -- Output Current vs. Temperature TSCR420 VOUT>2.0V, VEN=24V TSCR421 VOUT>2.0V, VEN=3.3V Output Current vs. Supply Voltage TSCR420 VOUT>2.0V, VEN=24V TSCR421 VOUT>2.0V, VEN=3.3V 2 ΔIOUT/IOUT ΔIOUT/IOUT %/°C %/V Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor ORDERING INFORMATION ORDERING CODE PACKAGE PACKING TSCR420CX6H RFG SOT-26 3,000pcs / 7”Reel TSCR421CX6H RFG SOT-26 3,000pcs / 7”Reel FUNCTION BLOCK OUT EN Regulator Vref Vref REXT RINT GND TSCR420/TSCR421 PIN DESCRIPTION PIN NO. NAME FUNCTION 1 EN 2 OUT Regulated output current 3 OUT Regulated output current 4 GND Power ground 5 OUT Regulated output current 6 REXT External resistor for adjusting output current Enable for biasing transistor 3 Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor TSCR420CX6 CHARACTERISTICS CURVES Figure 2. VOUT vs. IOUT (REXT=20Ω) Figure 1. VOUT vs. IOUT (REXT=open) Figure 3. VOUT vs IOUT (REXT=8.2Ω) Figure 4. VEN vs IOUT (REXT=open) Figure 5. VEN vs. IOUT (REXT=20Ω) Figure 6. VEN vs. IOUT (REXT=8.2Ω) 4 Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor TSCR420CX6 CHARACTERISTICS CURVES Figure 7. VEN vs. IEN (REXT=open) Figure 8. VEN vs. IEN (REXT=20Ω) Figure 9. VEN vs. IEN (REXT=8.2Ω) 5 Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor TSCR421CX6 CHARACTERISTICS CURVES Figure 10. VOUT vs. IOUT (REXT=open) Figure 11. VOUT vs. IOUT (REXT=20Ω) Figure 12. VOUT vs. IOUT (REXT=8.2Ω) Figure 13. VEN vs. IOUT (REXT=open) Figure 14. VEN vs. IOUT (REXT=20Ω) Figure 15. VEN vs. IOUT (REXT=8.2Ω) 6 Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor TSCR421CX6 CHARACTERISTICS CURVES Figure 16. VEN vs. IEN (REXT =open) Figure 17. VEN vs. IEN (REXT =20Ω) Figure 18. VEN vs. IEN (REXT=8.2Ω) Figure 19. PD vs. Ambient Temperature 7 Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor APPLICATION INFORMATION The TSCR420 & TSCR421 are designed for driving low current LEDs with typical LED currents of 10mA to 300mA. 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 20 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 TSCR421; or VEN = 24V and VOUT = 1.4V for TSCR420. 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 R EXT will improve the overall accuracy of the current sense formed by the parallel connection of RINT and REXT. REXT = VDROP / (IOUT – (VDROP/RINT)) Two or more TSCR420 & TSCR421 can be connected in parallel to construct higher current LED strings as shown in Figure 21. Consideration of the expected linear mode power dissipation must be factored into the design, with respect to the TSCR420 & TSCR421’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– VREXT) × ILED + (VEN × IEN) As the output current of TSCR420 & TSCR421 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 Refer to the thermal characteristic graphs on Page 4 for selecting the appropriate PCB copper area. Vs Supply Vs Supply LED String LED String Vref Vref OUT Regulator Vref Vref CEN CEN OUT Regulator Vref Vref REXT REXT RINT EN RINT (Optional) Figure 20: Typical Application Circuit for Linear Mode Current Sink LED Driver REXT RINT (Optional) GND GND TSCR420 TSCR421 Regulator EN TSCR420 TSCR421 OUT TSCR420 TSCR421 CEN EN (Optional) GND Figure 21: Application Circuit for Increasing LED Current 8 Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor APPLICATION INFORMATION (CONTINUE) 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 22. Vs Supply Vs Supply LED String LED String µC CEN EN OUT EN OUT Regulator Vref Regulator Vref Vref CEN Vref REXT RINT REXT (Optional) RINT GND (Optional) GND TSCR421 TSCR420 Figure 22: Application Circuit for LED Driver with PWM Dimming Functionality Figure 23: Application Circuit for LED Driver with High voltage EN Pin 9 Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor PACKAGE OUTLINE DIMENSIONS (Unit: Millimeters) SOT-26 SUGGESTED PAD LAYOUT (Unit: Millimeters) MARKING DIAGRAM Nx = Device Code N1 =TSCR420CX6 N2 =TSCR421CX6 Y = Year Code M = Month Code for Halogen Free Product O =Jan P =Feb Q =Mar R =Apr S =May T =Jun U =Jul V =Aug W =Sep X =Oct Y =Nov Z =Dec L = Lot Code (1~9, A~Z) 10 Version: A1812 TSCR420CX6H / TSCR421CX6H Taiwan Semiconductor Notice Specifications of the products displayed herein are subject to change without notice. TSC or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies. Information contained herein is intended to provide a product description only. No license, express or implied, to any intellectual property rights is granted by this document. Except as provided in TSC’s terms and conditions of sale for such products, TSC assumes no liability whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of TSC products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right. The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications. Customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify TSC for any damages resulting from such improper use or sale. 11 Version: A1812