TSCR420CX6 RFG

TSCR420CX6 / TSCR421CX6 Taiwan Semiconductor Linear Constant Current Regulated LED Driver DESCRIPTION FEATURES The TSCR420 & TSCR421 are Low-Side Constant ● LED drive current preset to 10mA Current Regulator (CCR) for linear LED driving. The ● Continuous output current up to 300mA with an device regulates with a preset 10mA nominal that can external resistor be adjusted with an external resistor up to 300mA. It is ● Very low enable current designed for driving LEDs in strings and will reduce ● Easy paralleling of drivers to increase current current at increasing temperatures to self-protect. ● Supply voltage up to 40V Operating as a series linear CCR for LED string ● Digital PWM input up to 10kHz (TSCR421) current control, it can be used in multiple applications, ● Good temperature coefficient vs. output current as long as the maximum supply voltage to the device ● Compliant to RoHS Directive 2011/65/EU and in is 2.0V, VEN=24V REXT=5.1Ω TSCR421 VOUT>2.0V, VEN=3.3V Output Current MIN IEN IRINT=10mA Internal Resistor SYMBOL 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: B1708 TSCR420CX6 / TSCR421CX6 Taiwan Semiconductor ORDERING INFORMATION PART NO. PACKAGE PACKING TSCR420CX6 RFG SOT-26 3,000pcs / 7”Reel TSCR421CX6 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: B1708 TSCR420CX6 / TSCR421CX6 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: B1708 TSCR420CX6 / TSCR421CX6 Taiwan Semiconductor TSCR420CX6 CHARACTERISTICS CURVES Figure 7. VEN vs. IEN (REXT=open) Figure 8. VEN vs. IEN (A5) Figure 9. VEN vs. IEN (REXT=8.2Ω) 5 Version: B1708 TSCR420CX6 / TSCR421CX6 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: B1708 TSCR420CX6 / TSCR421CX6 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: B1708 TSCR420CX6 / TSCR421CX6 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, R EXT. 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 R INT 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 × 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 Vref Vref OUT Regulator Vref Vref OUT Regulator Vref Vref REXT RINT EN REXT (Optional) RINT GND TSCR420 TSCR421 Regulator EN TSCR420 TSCR421 OUT TSCR420 TSCR421 EN LED String REXT (Optional) GND RINT (Optional) GND Figure 20: Typical Application Circuit for Linear Figure 21: Application Circuit for Increasing LED Mode Current Sink LED Driver Current 8 Version: B1708 TSCR420CX6 / TSCR421CX6 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 EN OUT EN OUT Regulator Vref Regulator Vref Vref 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: B1708 TSCR420CX6 / TSCR421CX6 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: B1708 TSCR420CX6 / TSCR421CX6 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: B1708