Preliminary TS19453 AC/DC Programmable Current WLED Driver w/PWM Dimming Control SOP-8 Pin Definition: 1. Rsense 8. Drain 2. Ground 7. Drain 3. PWMD 6. Drain 4. Vdd 5. Ground General Description The TS19453 is a PWM high efficiency programmable current LED driver with PWM dimming control IC. It allows efficient operation of LED strings from voltage source ranging up to 400VDC. It includes an internal high voltage switching MOSFET controlled with fixed off-time of approximately 12µS. The LED string is driven at constant current, thus providing constant light output and enhanced reliability. The output current is internally programmable up to 50mA. The peak current control scheme provides good regulation of the output current throughout the universal AC line voltage range of 85~264VAC or DC input voltage of 20~400V Features Typical Application Circuit ● Adjust constant output current up to 50mA(typ) ● Universal 85~264VAC operation ● Over temperature protection with hysteresis ● PWM dimming ● Fixed off-time buck converter ● Internal 475V power MOSFET Application ● Decorating LED lighting ● LED lamps with AC or DC operation. Ordering Information Part No. TS19453CS RLG Package Packing SOP-8 2.5Kpcs/13” Reel Note: “G” denote for Halogen Free Product Absolute Maximum Rating Parameter Symbol Limit Unit Input Voltage Range VIN to GND ~ +475 V VDD to GND VDD to GND ~9 uA ~ VDD+0.3 uA PMWD, Rsense to GND Power Dissipation @ TA=25ºC PD Internally Limited W Operating Ambient Temperature TOPR -40 to +85 ºC Storage Temperature Range TSTG -65 to +150 Thermal Resistance – Junction to Ambient RθJA 160 o C o C/W Note: Stresses beyond those listed under ”Absolute Maximum Ratings” may cause permanent damage to the device. These are stress rating only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 1/7 Version: Preliminary Preliminary TS19453 AC/DC Programmable Current WLED Driver w/PWM Dimming Control Electrical Specifications (Ta = 25oC, VDRAIN= 50V, unless otherwise noted) Function Parameter Symbol Test Conditions Min Typ Max Units VDD -- 7.5 -- V Drain Supply Voltage VDRAIN 20 -- 400 V Undervoltage Lockout Threshold UVLO VDD rising 4.8 -- -- V Undervoltage Lockout Hysteresis ∆UVLO VDD falling -- 200 -- mV IDD VDD(EXT)=8.0V -- -- 500 µA VBR Note 1 475 -- -- V -- -- 200 Ω 100 150 -- mA Note 1 0.43 -- 0.53 V Note 1,2 200 300 400 nS Internal Regulator Internally Regulated Voltage Supply Current Output (Drain) Breakdown Voltage On Resistance MOSFET Saturation current RDSON IDRAIN=50mA ISAT Current Sense Comparator Threshold Voltage VTH Leading edge Blanking delay TBLANK Minimum Turn On-Time TON(min) -- -- 650 nS TOFF 8 12 18 µS High voltage 2.0 -- -- V Low voltage -- -- 0.8 VPWMD=5V 100 -- 300 Off-Time Generator Turn On-Time PWMD PWMD Input Voltage VPWMD PWMD Pull Down Resistance RPWMD Ω Note 1: The specification which apply over the full operating ambient temperature range of -40ºC<TA<+85ºC 2: Guaranteed by design Block Diagram 2/7 Version: Preliminary Preliminary TS19453 AC/DC Programmable Current WLED Driver w/PWM Dimming Control Function Description The TS19453 is a PWM peak current controller for controlling a buck converter topology in continuous conduction mode (CCM). The output current is of converter that can be programmed by a single external resistor (Rsense), for the purpose of driving a string of LED, an external enable input (PWMD) is provided that can be utilized for PWM dimming of an LED string. When the input voltage of 20~400V appears at the Drain pin, the internal high-voltage linear regulator seeks to maintain a voltage of 7.5VDC at the VDD pin. Until this voltage exceeds the internally programmed under-voltage threshold, the output switching MOSFET is non-conductive. When the threshold is exceeded, the integrated highvoltage switch turns on, pulling the Drain low, A 200mV hysteresis is incorporated with the undervoltage comparator to prevent oscillation. When the voltage at Rsense exceeds 0.47V(typ), the switch turns off and the Drain output becomes high impedance, at the same time, a one shot circuit is activated that determines the off-time of the switch. A “blanking” delay of 300nS is provided that presents false triggering of the current sense comparator due to the leading edge spike caused by circuit parasitic. Application Information The TS19453 is specifically designed for driving multi LED strings. It can be operated from either universal AC line range of 85~264VAC or 20~400VDC, and drives up to tens of high brightness LEDs. All LEDs can be run in series and this device regulates at constant current, yielding uniform illumination. Selecting L1 and D1 There is a certain trade-off to be considered between optimal sizing of the output inductor L1 and the tolerated output current ripple. The required value of L1 is inversely proportional to the ripple current ∆IO in it. L1 = (VO x TOFF) / ∆IO VO is the forward voltage of the LED string. TOFF is the off-time of the TS19453. The output current in the LED string (IO) is calculated as: IO = (Vth / Rsense) – (∆IO / 2) Where ITH is the current sense comparator threshold, and Rsense is the current sense resistor. The ripple current introduces a peak-to-average error in the output current setting that needs to be accounted for. Due to constant offtime control technique used in the TS19453, the ripple current is independent of the input AC or DC line voltage variation. Therefore, the output current will remain unaffected by the varying input voltage. Adding a filter capacitor across the LED string can reduce the output current ripple even further, thus permitting a reduced value of L1. However, one must keep in mind that the peak-to-average current error is affected by the variation of TOFF. Therefore, the initial output current accuracy might be sacrificed at large ripple current in L1. Another important aspect of designing an LED driver with TS19453 is related to certain parasitic elements of the circuit, including distributed coil capacitance of L1, junction capacitance and reverse recover of the rectifier diode D1, capacitance of the PCB traces CPCB and output capacitance CDRAIN of the controller itself. These parasitic elements affect the efficiency of the switching converter and could potentially cause false triggering of the current sense comparator if not properly managed. Minimizing these parasitic is essential for efficient and reliable operation. Coil capacitance of inductors is typically provided in the manufacturer’s data books either directly or in terms of the self-resonant frequency (SRF). SRF = 1 / (2π√(L * CL)) 3/7 Version: Preliminary Preliminary TS19453 AC/DC Programmable Current WLED Driver w/PWM Dimming Control Application Information (Continue) L is the inductance value, and CL is the coil capacitance. Charging and discharging this capacitance every switching cycle causes high-current spikes in the LED string. Therefore, connecting a small capacitor CO(~100nF) is recommended to bypass these spikes. Using an ultra-fast rectifier diode for D1 is recommended to achieve high efficiency and reduce the risk of false triggering of the current sense comparator. Using diodes with shorter reverse recovery time trr and lower junction capacitance CJ achieves better performance. The reverse voltage rating VR of the diode must be greater than the maximum input voltage of LED lamps. The total parasitic capacitance present at the Drain pin of the TS19453 can be calculated as: CP = CDRAIN + CPCB + CL + CJ When the switching MOSFET turns on, the capacitance CP is discharged into the Drain pin of the IC. The discharge current is limited to about 50mA typically. However, it may become lower at increased junction temperature. The duration of the leading edge current spike can be estimated as: TPSIKE = ((VIN x CP) / (ISAT)) + trr In order to avoid false trigger of the current sense comparator, CP must be minimized in accordance with the following expression. CP =< (Isat * ( TBLANK(min) - trr )) / Vin(max) When TBLANK(min) is the minimum blanking time of 200nS, and Vin(max) is the maximum instantaneous input voltage. Estimating Power Loss Discharging the parasitic capacitance CP in the the Drain output of TS19453 is responsible for the bulk of the switching power loss. It can be estimated using as: 2 PSWITCH = ((CP * VIN / 2 ) + (VIN * ISAT * trr)) * FS FS is the switching frequency and is the saturated Drain current of TS19453, the switching loss is the greatest at the maximum input voltage. Disregarding the voltage drop at TS19453 and D1, the switching frequency is given as FS = (VIN - VOUT ) / (VIN * TOFF) When the TS19453 is powered from full wave rectified AC input, the swithching power loss can be estimated as: PSWITCH = 1 / (2 * TOFF) * ((VAC * CP + 2 * ISAT * trr ) * (VAC - VOUT ))) When the TS19453 is powered from DC input voltage, conduction power loss can be estimated as: 2 PCOND = (D * IOUT * RON) + IDD * VIN * (1 – D) EMI Filter As with all off-line converters, selecting an input filter is critical to obtaining good EMI. A switching side capacitor, albeit of small value, is necessary in order to ensure low impedance to the high frequency switching currents of the converter. As a rule of thumb, this capacitor should be approximately 0.1~0.2µF/W of LED output power. 4/7 Version: Preliminary Preliminary TS19453 AC/DC Programmable Current WLED Driver w/PWM Dimming Control Typical Application Circuit Typical Application Circuit for Universal 85~264VAC LED Lamps Driver (Non-Isolation) 15pcs LED (VLED=49.5V), LED current 50mA 5/7 Version: Preliminary Preliminary TS19453 AC/DC Programmable Current WLED Driver w/PWM Dimming Control SOP-8 Mechanical Drawing DIM A B C D F G K M P R 6/7 SOP-8 DIMENSION MILLIMETERS INCHES MIN MAX MIN MAX. 4.80 5.00 0.189 0.196 3.80 4.00 0.150 0.157 1.35 1.75 0.054 0.068 0.35 0.49 0.014 0.019 0.40 1.25 0.016 0.049 1.27BSC 0.05BSC 0.10 0.25 0.004 0.009 0º 7º 0º 7º 5.80 6.20 0.229 0.244 0.25 0.50 0.010 0.019 Version: Preliminary Preliminary TS19453 AC/DC Programmable Current WLED Driver w/PWM Dimming Control 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. 7/7 Version: Preliminary